///////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////
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//
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//
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// Filename: zipcpu.v
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// Filename: zipcpu.v
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//
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//
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// Project: Zip CPU -- a small, lightweight, RISC CPU soft core
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// Project: Zip CPU -- a small, lightweight, RISC CPU soft core
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//
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//
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// Purpose: This is the top level module holding the core of the Zip CPU
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// Purpose: This is the top level module holding the core of the Zip CPU
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// together. The Zip CPU is designed to be as simple as possible.
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// together. The Zip CPU is designed to be as simple as possible.
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// (actual implementation aside ...) The instruction set is about as
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// (actual implementation aside ...) The instruction set is about as
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// RISC as you can get, there are only 16 instruction types supported.
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// RISC as you can get, there are only 16 instruction types supported.
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// Please see the accompanying spec.pdf file for a description of these
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// Please see the accompanying spec.pdf file for a description of these
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// instructions.
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// instructions.
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//
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//
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// All instructions are 32-bits wide. All bus accesses, both address and
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// All instructions are 32-bits wide. All bus accesses, both address and
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// data, are 32-bits over a wishbone bus.
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// data, are 32-bits over a wishbone bus.
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//
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//
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// The Zip CPU is fully pipelined with the following pipeline stages:
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// The Zip CPU is fully pipelined with the following pipeline stages:
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//
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//
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// 1. Prefetch, returns the instruction from memory.
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// 1. Prefetch, returns the instruction from memory.
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//
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//
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// 2. Instruction Decode
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// 2. Instruction Decode
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//
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//
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// 3. Read Operands
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// 3. Read Operands
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//
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//
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// 4. Apply Instruction
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// 4. Apply Instruction
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//
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//
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// 4. Write-back Results
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// 4. Write-back Results
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//
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//
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// Further information about the inner workings of this CPU may be
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// Further information about the inner workings of this CPU may be
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// found in the spec.pdf file. (The documentation within this file
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// found in the spec.pdf file. (The documentation within this file
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// had become out of date and out of sync with the spec.pdf, so look
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// had become out of date and out of sync with the spec.pdf, so look
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// to the spec.pdf for accurate and up to date information.)
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// to the spec.pdf for accurate and up to date information.)
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//
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//
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//
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//
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// In general, the pipelining is controlled by three pieces of logic
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// In general, the pipelining is controlled by three pieces of logic
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// per stage: _ce, _stall, and _valid. _valid means that the stage
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// per stage: _ce, _stall, and _valid. _valid means that the stage
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// holds a valid instruction. _ce means that the instruction from the
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// holds a valid instruction. _ce means that the instruction from the
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// previous stage is to move into this one, and _stall means that the
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// previous stage is to move into this one, and _stall means that the
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// instruction from the previous stage may not move into this one.
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// instruction from the previous stage may not move into this one.
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// The difference between these control signals allows individual stages
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// The difference between these control signals allows individual stages
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// to propagate instructions independently. In general, the logic works
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// to propagate instructions independently. In general, the logic works
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// as:
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// as:
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//
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//
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//
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//
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// assign (n)_ce = (n-1)_valid && (~(n)_stall)
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// assign (n)_ce = (n-1)_valid && (~(n)_stall)
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//
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//
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//
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//
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// always @(posedge i_clk)
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// always @(posedge i_clk)
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// if ((i_rst)||(clear_pipeline))
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// if ((i_rst)||(clear_pipeline))
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// (n)_valid = 0
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// (n)_valid = 0
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// else if (n)_ce
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// else if (n)_ce
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// (n)_valid = 1
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// (n)_valid = 1
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// else if (n+1)_ce
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// else if (n+1)_ce
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// (n)_valid = 0
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// (n)_valid = 0
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//
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//
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// assign (n)_stall = ( (n-1)_valid && ( pipeline hazard detection ) )
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// assign (n)_stall = ( (n-1)_valid && ( pipeline hazard detection ) )
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// || ( (n)_valid && (n+1)_stall );
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// || ( (n)_valid && (n+1)_stall );
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//
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//
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// and ...
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// and ...
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//
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//
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// always @(posedge i_clk)
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// always @(posedge i_clk)
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// if (n)_ce
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// if (n)_ce
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// (n)_variable = ... whatever logic for this stage
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// (n)_variable = ... whatever logic for this stage
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//
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//
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// Note that a stage can stall even if no instruction is loaded into
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// Note that a stage can stall even if no instruction is loaded into
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// it.
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// it.
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//
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//
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//
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//
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// Creator: Dan Gisselquist, Ph.D.
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// Creator: Dan Gisselquist, Ph.D.
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// Gisselquist Technology, LLC
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// Gisselquist Technology, LLC
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//
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//
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///////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////
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//
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//
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// Copyright (C) 2015, Gisselquist Technology, LLC
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// Copyright (C) 2015, Gisselquist Technology, LLC
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//
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//
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// This program is free software (firmware): you can redistribute it and/or
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// This program is free software (firmware): you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as published
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// modify it under the terms of the GNU General Public License as published
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// by the Free Software Foundation, either version 3 of the License, or (at
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// by the Free Software Foundation, either version 3 of the License, or (at
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// your option) any later version.
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// your option) any later version.
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//
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
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// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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// for more details.
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//
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//
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// License: GPL, v3, as defined and found on www.gnu.org,
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// License: GPL, v3, as defined and found on www.gnu.org,
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// http://www.gnu.org/licenses/gpl.html
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// http://www.gnu.org/licenses/gpl.html
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//
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//
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//
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//
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///////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////
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//
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//
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// We can either pipeline our fetches, or issue one fetch at a time. Pipelined
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// We can either pipeline our fetches, or issue one fetch at a time. Pipelined
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// fetches are more complicated and therefore use more FPGA resources, while
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// fetches are more complicated and therefore use more FPGA resources, while
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// single fetches will cause the CPU to stall for about 5 stalls each
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// single fetches will cause the CPU to stall for about 5 stalls each
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// instruction cycle, effectively reducing the instruction count per clock to
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// instruction cycle, effectively reducing the instruction count per clock to
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// about 0.2. However, the area cost may be worth it. Consider:
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// about 0.2. However, the area cost may be worth it. Consider:
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//
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//
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// Slice LUTs ZipSystem ZipCPU
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// Slice LUTs ZipSystem ZipCPU
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// Single Fetching 2521 1734
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// Single Fetching 2521 1734
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// Pipelined fetching 2796 2046
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// Pipelined fetching 2796 2046
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//
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//
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//
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//
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//
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//
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`define CPU_CC_REG 4'he
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`define CPU_CC_REG 4'he
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`define CPU_PC_REG 4'hf
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`define CPU_PC_REG 4'hf
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`define CPU_FPUERR_BIT 12 // Floating point error flag, set on error
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`define CPU_FPUERR_BIT 12 // Floating point error flag, set on error
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`define CPU_DIVERR_BIT 11 // Divide error flag, set on divide by zero
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`define CPU_DIVERR_BIT 11 // Divide error flag, set on divide by zero
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`define CPU_BUSERR_BIT 10 // Bus error flag, set on error
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`define CPU_BUSERR_BIT 10 // Bus error flag, set on error
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`define CPU_TRAP_BIT 9 // User TRAP has taken place
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`define CPU_TRAP_BIT 9 // User TRAP has taken place
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`define CPU_ILL_BIT 8 // Illegal instruction
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`define CPU_ILL_BIT 8 // Illegal instruction
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`define CPU_BREAK_BIT 7
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`define CPU_BREAK_BIT 7
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`define CPU_STEP_BIT 6 // Will step one or two (VLIW) instructions
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`define CPU_STEP_BIT 6 // Will step one or two (VLIW) instructions
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`define CPU_GIE_BIT 5
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`define CPU_GIE_BIT 5
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`define CPU_SLEEP_BIT 4
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`define CPU_SLEEP_BIT 4
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// Compile time defines
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// Compile time defines
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//
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//
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`include "cpudefs.v"
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`include "cpudefs.v"
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//
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//
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//
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//
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module zipcpu(i_clk, i_rst, i_interrupt,
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module zipcpu(i_clk, i_rst, i_interrupt,
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// Debug interface
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// Debug interface
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i_halt, i_clear_pf_cache, i_dbg_reg, i_dbg_we, i_dbg_data,
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i_halt, i_clear_pf_cache, i_dbg_reg, i_dbg_we, i_dbg_data,
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o_dbg_stall, o_dbg_reg, o_dbg_cc,
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o_dbg_stall, o_dbg_reg, o_dbg_cc,
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o_break,
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o_break,
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// CPU interface to the wishbone bus
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// CPU interface to the wishbone bus
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o_wb_gbl_cyc, o_wb_gbl_stb,
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o_wb_gbl_cyc, o_wb_gbl_stb,
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o_wb_lcl_cyc, o_wb_lcl_stb,
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o_wb_lcl_cyc, o_wb_lcl_stb,
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o_wb_we, o_wb_addr, o_wb_data,
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o_wb_we, o_wb_addr, o_wb_data,
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i_wb_ack, i_wb_stall, i_wb_data,
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i_wb_ack, i_wb_stall, i_wb_data,
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i_wb_err,
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i_wb_err,
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// Accounting/CPU usage interface
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// Accounting/CPU usage interface
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o_op_stall, o_pf_stall, o_i_count
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o_op_stall, o_pf_stall, o_i_count
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`ifdef DEBUG_SCOPE
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`ifdef DEBUG_SCOPE
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, o_debug
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, o_debug
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`endif
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`endif
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);
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);
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parameter RESET_ADDRESS=32'h0100000, ADDRESS_WIDTH=24,
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parameter RESET_ADDRESS=32'h0100000, ADDRESS_WIDTH=24,
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LGICACHE=6;
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LGICACHE=6;
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`ifdef OPT_MULTIPLY
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`ifdef OPT_MULTIPLY
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parameter IMPLEMENT_MPY = 1;
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parameter IMPLEMENT_MPY = `OPT_MULTIPLY;
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`else
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`else
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parameter IMPLEMENT_MPY = 0;
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parameter IMPLEMENT_MPY = 0;
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`endif
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`endif
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`ifdef OPT_DIVIDE
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`ifdef OPT_DIVIDE
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parameter IMPLEMENT_DIVIDE = 1;
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parameter IMPLEMENT_DIVIDE = 1;
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`else
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`else
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parameter IMPLEMENT_DIVIDE = 0;
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parameter IMPLEMENT_DIVIDE = 0;
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`endif
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`endif
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`ifdef OPT_IMPLEMENT_FPU
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`ifdef OPT_IMPLEMENT_FPU
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parameter IMPLEMENT_FPU = 1,
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parameter IMPLEMENT_FPU = 1,
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`else
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`else
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parameter IMPLEMENT_FPU = 0,
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parameter IMPLEMENT_FPU = 0,
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`endif
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`endif
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IMPLEMENT_LOCK=1;
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IMPLEMENT_LOCK=1;
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`ifdef OPT_EARLY_BRANCHING
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`ifdef OPT_EARLY_BRANCHING
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parameter EARLY_BRANCHING = 1;
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parameter EARLY_BRANCHING = 1;
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`else
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`else
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parameter EARLY_BRANCHING = 0;
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parameter EARLY_BRANCHING = 0;
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`endif
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`endif
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parameter AW=ADDRESS_WIDTH;
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parameter AW=ADDRESS_WIDTH;
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input i_clk, i_rst, i_interrupt;
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input i_clk, i_rst, i_interrupt;
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// Debug interface -- inputs
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// Debug interface -- inputs
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input i_halt, i_clear_pf_cache;
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input i_halt, i_clear_pf_cache;
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input [4:0] i_dbg_reg;
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input [4:0] i_dbg_reg;
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input i_dbg_we;
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input i_dbg_we;
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input [31:0] i_dbg_data;
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input [31:0] i_dbg_data;
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// Debug interface -- outputs
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// Debug interface -- outputs
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output reg o_dbg_stall;
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output reg o_dbg_stall;
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output reg [31:0] o_dbg_reg;
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output reg [31:0] o_dbg_reg;
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output reg [3:0] o_dbg_cc;
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output reg [3:0] o_dbg_cc;
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output wire o_break;
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output wire o_break;
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// Wishbone interface -- outputs
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// Wishbone interface -- outputs
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output wire o_wb_gbl_cyc, o_wb_gbl_stb;
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output wire o_wb_gbl_cyc, o_wb_gbl_stb;
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output wire o_wb_lcl_cyc, o_wb_lcl_stb, o_wb_we;
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output wire o_wb_lcl_cyc, o_wb_lcl_stb, o_wb_we;
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output wire [(AW-1):0] o_wb_addr;
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output wire [(AW-1):0] o_wb_addr;
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output wire [31:0] o_wb_data;
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output wire [31:0] o_wb_data;
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// Wishbone interface -- inputs
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// Wishbone interface -- inputs
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input i_wb_ack, i_wb_stall;
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input i_wb_ack, i_wb_stall;
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input [31:0] i_wb_data;
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input [31:0] i_wb_data;
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input i_wb_err;
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input i_wb_err;
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// Accounting outputs ... to help us count stalls and usage
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// Accounting outputs ... to help us count stalls and usage
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output wire o_op_stall;
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output wire o_op_stall;
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output wire o_pf_stall;
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output wire o_pf_stall;
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output wire o_i_count;
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output wire o_i_count;
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//
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//
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`ifdef DEBUG_SCOPE
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`ifdef DEBUG_SCOPE
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output reg [31:0] o_debug;
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output reg [31:0] o_debug;
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`endif
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`endif
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// Registers
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// Registers
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//
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//
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// The distributed RAM style comment is necessary on the
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// The distributed RAM style comment is necessary on the
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// SPARTAN6 with XST to prevent XST from oversimplifying the register
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// SPARTAN6 with XST to prevent XST from oversimplifying the register
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// set and in the process ruining everything else. It basically
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// set and in the process ruining everything else. It basically
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// optimizes logic away, to where it no longer works. The logic
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// optimizes logic away, to where it no longer works. The logic
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// as described herein will work, this just makes sure XST implements
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// as described herein will work, this just makes sure XST implements
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// that logic.
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// that logic.
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//
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//
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(* ram_style = "distributed" *)
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(* ram_style = "distributed" *)
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reg [31:0] regset [0:31];
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reg [31:0] regset [0:31];
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// Condition codes
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// Condition codes
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// (BUS, TRAP,ILL,BREAKEN,STEP,GIE,SLEEP ), V, N, C, Z
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// (BUS, TRAP,ILL,BREAKEN,STEP,GIE,SLEEP ), V, N, C, Z
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reg [3:0] flags, iflags;
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reg [3:0] flags, iflags;
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wire [13:0] w_uflags, w_iflags;
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wire [13:0] w_uflags, w_iflags;
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reg trap, break_en, step, gie, sleep;
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reg trap, break_en, step, gie, sleep;
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`ifdef OPT_ILLEGAL_INSTRUCTION
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`ifdef OPT_ILLEGAL_INSTRUCTION
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reg ill_err_u, ill_err_i;
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reg ill_err_u, ill_err_i;
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`else
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`else
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wire ill_err_u, ill_err_i;
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wire ill_err_u, ill_err_i;
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`endif
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`endif
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reg ibus_err_flag, ubus_err_flag;
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reg ibus_err_flag, ubus_err_flag;
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wire idiv_err_flag, udiv_err_flag;
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wire idiv_err_flag, udiv_err_flag;
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wire ifpu_err_flag, ufpu_err_flag;
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wire ifpu_err_flag, ufpu_err_flag;
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wire ihalt_phase, uhalt_phase;
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wire ihalt_phase, uhalt_phase;
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// The master chip enable
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// The master chip enable
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wire master_ce;
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wire master_ce;
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//
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//
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//
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//
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// PIPELINE STAGE #1 :: Prefetch
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// PIPELINE STAGE #1 :: Prefetch
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// Variable declarations
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// Variable declarations
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//
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//
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reg [(AW-1):0] pf_pc;
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reg [(AW-1):0] pf_pc;
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reg new_pc;
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reg new_pc;
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wire clear_pipeline;
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wire clear_pipeline;
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assign clear_pipeline = new_pc || i_clear_pf_cache;
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assign clear_pipeline = new_pc || i_clear_pf_cache;
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wire dcd_stalled;
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wire dcd_stalled;
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wire pf_cyc, pf_stb, pf_we, pf_busy, pf_ack, pf_stall, pf_err;
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wire pf_cyc, pf_stb, pf_we, pf_busy, pf_ack, pf_stall, pf_err;
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wire [(AW-1):0] pf_addr;
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wire [(AW-1):0] pf_addr;
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wire [31:0] pf_data;
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wire [31:0] pf_data;
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wire [31:0] instruction;
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wire [31:0] instruction;
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wire [(AW-1):0] instruction_pc;
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wire [(AW-1):0] instruction_pc;
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wire pf_valid, instruction_gie, pf_illegal;
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wire pf_valid, instruction_gie, pf_illegal;
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//
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//
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//
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//
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// PIPELINE STAGE #2 :: Instruction Decode
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// PIPELINE STAGE #2 :: Instruction Decode
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// Variable declarations
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// Variable declarations
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//
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//
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//
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//
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reg opvalid, opvalid_mem, opvalid_alu;
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reg opvalid, opvalid_mem, opvalid_alu;
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reg opvalid_div, opvalid_fpu;
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reg opvalid_div, opvalid_fpu;
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wire op_stall, dcd_ce, dcd_phase;
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wire op_stall, dcd_ce, dcd_phase;
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wire [3:0] dcdOp;
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wire [3:0] dcdOp;
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wire [4:0] dcdA, dcdB, dcdR;
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wire [4:0] dcdA, dcdB, dcdR;
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wire dcdA_cc, dcdB_cc, dcdA_pc, dcdB_pc, dcdR_cc, dcdR_pc;
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wire dcdA_cc, dcdB_cc, dcdA_pc, dcdB_pc, dcdR_cc, dcdR_pc;
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wire [3:0] dcdF;
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wire [3:0] dcdF;
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wire dcdR_wr, dcdA_rd, dcdB_rd,
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wire dcdR_wr, dcdA_rd, dcdB_rd,
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dcdALU, dcdM, dcdDV, dcdFP,
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dcdALU, dcdM, dcdDV, dcdFP,
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dcdF_wr, dcd_gie, dcd_break, dcd_lock,
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dcdF_wr, dcd_gie, dcd_break, dcd_lock,
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dcd_pipe, dcd_ljmp;
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dcd_pipe, dcd_ljmp;
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reg r_dcdvalid;
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reg r_dcdvalid;
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wire dcdvalid;
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wire dcdvalid;
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wire [(AW-1):0] dcd_pc;
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wire [(AW-1):0] dcd_pc;
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wire [31:0] dcdI;
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wire [31:0] dcdI;
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wire dcd_zI; // true if dcdI == 0
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wire dcd_zI; // true if dcdI == 0
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wire dcdA_stall, dcdB_stall, dcdF_stall;
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wire dcdA_stall, dcdB_stall, dcdF_stall;
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|
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wire dcd_illegal;
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wire dcd_illegal;
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wire dcd_early_branch;
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wire dcd_early_branch;
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wire [(AW-1):0] dcd_branch_pc;
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wire [(AW-1):0] dcd_branch_pc;
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|
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|
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//
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//
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//
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//
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// PIPELINE STAGE #3 :: Read Operands
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// PIPELINE STAGE #3 :: Read Operands
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// Variable declarations
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// Variable declarations
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//
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//
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//
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//
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//
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//
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// Now, let's read our operands
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// Now, let's read our operands
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reg [4:0] alu_reg;
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reg [4:0] alu_reg;
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reg [3:0] opn;
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reg [3:0] opn;
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reg [4:0] opR;
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reg [4:0] opR;
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reg [31:0] r_opA, r_opB;
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reg [31:0] r_opA, r_opB;
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reg [(AW-1):0] op_pc;
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reg [(AW-1):0] op_pc;
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wire [31:0] w_opA, w_opB;
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wire [31:0] w_opA, w_opB;
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wire [31:0] opA_nowait, opB_nowait, opA, opB;
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wire [31:0] opA_nowait, opB_nowait, opA, opB;
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reg opR_wr, opR_cc, opF_wr, op_gie;
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reg opR_wr, opR_cc, opF_wr, op_gie;
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wire [13:0] opFl;
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wire [13:0] opFl;
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reg [5:0] r_opF;
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reg [5:0] r_opF;
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wire [7:0] opF;
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wire [7:0] opF;
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wire op_ce, op_phase, op_pipe;
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wire op_ce, op_phase, op_pipe;
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// Some pipeline control wires
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// Some pipeline control wires
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`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
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reg opA_alu, opA_mem;
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reg opA_alu, opA_mem;
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reg opB_alu, opB_mem;
|
reg opB_alu, opB_mem;
|
`endif
|
`endif
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
reg op_illegal;
|
reg op_illegal;
|
`endif
|
`endif
|
reg op_break;
|
reg op_break;
|
wire op_lock;
|
wire op_lock;
|
|
|
|
|
//
|
//
|
//
|
//
|
// PIPELINE STAGE #4 :: ALU / Memory
|
// PIPELINE STAGE #4 :: ALU / Memory
|
// Variable declarations
|
// Variable declarations
|
//
|
//
|
//
|
//
|
reg [(AW-1):0] alu_pc;
|
reg [(AW-1):0] alu_pc;
|
reg alu_pc_valid, mem_pc_valid;
|
reg alu_pc_valid, mem_pc_valid;
|
wire alu_phase;
|
wire alu_phase;
|
wire alu_ce, alu_stall;
|
wire alu_ce, alu_stall;
|
wire [31:0] alu_result;
|
wire [31:0] alu_result;
|
wire [3:0] alu_flags;
|
wire [3:0] alu_flags;
|
wire alu_valid, alu_busy;
|
wire alu_valid, alu_busy;
|
wire set_cond;
|
wire set_cond;
|
reg alu_wr, alF_wr, alu_gie;
|
reg alu_wr, alF_wr, alu_gie;
|
wire alu_illegal_op;
|
wire alu_illegal_op;
|
wire alu_illegal;
|
wire alu_illegal;
|
|
|
|
|
|
|
wire mem_ce, mem_stalled;
|
wire mem_ce, mem_stalled;
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
wire mem_pipe_stalled;
|
wire mem_pipe_stalled;
|
`endif
|
`endif
|
wire mem_valid, mem_ack, mem_stall, mem_err, bus_err,
|
wire mem_valid, mem_ack, mem_stall, mem_err, bus_err,
|
mem_cyc_gbl, mem_cyc_lcl, mem_stb_gbl, mem_stb_lcl, mem_we;
|
mem_cyc_gbl, mem_cyc_lcl, mem_stb_gbl, mem_stb_lcl, mem_we;
|
wire [4:0] mem_wreg;
|
wire [4:0] mem_wreg;
|
|
|
wire mem_busy, mem_rdbusy;
|
wire mem_busy, mem_rdbusy;
|
wire [(AW-1):0] mem_addr;
|
wire [(AW-1):0] mem_addr;
|
wire [31:0] mem_data, mem_result;
|
wire [31:0] mem_data, mem_result;
|
|
|
wire div_ce, div_error, div_busy, div_valid;
|
wire div_ce, div_error, div_busy, div_valid;
|
wire [31:0] div_result;
|
wire [31:0] div_result;
|
wire [3:0] div_flags;
|
wire [3:0] div_flags;
|
|
|
assign div_ce = (master_ce)&&(~clear_pipeline)&&(opvalid_div)
|
assign div_ce = (master_ce)&&(~clear_pipeline)&&(opvalid_div)
|
&&(~mem_rdbusy)&&(~div_busy)&&(~fpu_busy)
|
&&(~mem_rdbusy)&&(~div_busy)&&(~fpu_busy)
|
&&(set_cond);
|
&&(set_cond);
|
|
|
wire fpu_ce, fpu_error, fpu_busy, fpu_valid;
|
wire fpu_ce, fpu_error, fpu_busy, fpu_valid;
|
wire [31:0] fpu_result;
|
wire [31:0] fpu_result;
|
wire [3:0] fpu_flags;
|
wire [3:0] fpu_flags;
|
|
|
assign fpu_ce = (master_ce)&&(~clear_pipeline)&&(opvalid_fpu)
|
assign fpu_ce = (master_ce)&&(~clear_pipeline)&&(opvalid_fpu)
|
&&(~mem_rdbusy)&&(~div_busy)&&(~fpu_busy)
|
&&(~mem_rdbusy)&&(~div_busy)&&(~fpu_busy)
|
&&(set_cond);
|
&&(set_cond);
|
|
|
|
|
//
|
//
|
//
|
//
|
// PIPELINE STAGE #5 :: Write-back
|
// PIPELINE STAGE #5 :: Write-back
|
// Variable declarations
|
// Variable declarations
|
//
|
//
|
wire wr_reg_ce, wr_flags_ce, wr_write_pc, wr_write_cc;
|
wire wr_reg_ce, wr_flags_ce, wr_write_pc, wr_write_cc;
|
wire [4:0] wr_reg_id;
|
wire [4:0] wr_reg_id;
|
wire [31:0] wr_reg_vl;
|
wire [31:0] wr_reg_vl;
|
wire w_switch_to_interrupt, w_release_from_interrupt;
|
wire w_switch_to_interrupt, w_release_from_interrupt;
|
reg [(AW-1):0] upc, ipc;
|
reg [(AW-1):0] upc, ipc;
|
|
|
|
|
|
|
//
|
//
|
// MASTER: clock enable.
|
// MASTER: clock enable.
|
//
|
//
|
assign master_ce = (~i_halt)&&(~o_break)&&(~sleep);
|
assign master_ce = (~i_halt)&&(~o_break)&&(~sleep);
|
|
|
|
|
//
|
//
|
// PIPELINE STAGE #1 :: Prefetch
|
// PIPELINE STAGE #1 :: Prefetch
|
// Calculate stall conditions
|
// Calculate stall conditions
|
//
|
//
|
// These are calculated externally, within the prefetch module.
|
// These are calculated externally, within the prefetch module.
|
//
|
//
|
|
|
//
|
//
|
// PIPELINE STAGE #2 :: Instruction Decode
|
// PIPELINE STAGE #2 :: Instruction Decode
|
// Calculate stall conditions
|
// Calculate stall conditions
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign dcd_ce = ((~dcdvalid)||(~dcd_stalled))&&(~clear_pipeline);
|
assign dcd_ce = ((~dcdvalid)||(~dcd_stalled))&&(~clear_pipeline);
|
`else
|
`else
|
assign dcd_ce = 1'b1;
|
assign dcd_ce = 1'b1;
|
`endif
|
`endif
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign dcd_stalled = (dcdvalid)&&(op_stall);
|
assign dcd_stalled = (dcdvalid)&&(op_stall);
|
`else
|
`else
|
// If not pipelined, there will be no opvalid_ anything, and the
|
// If not pipelined, there will be no opvalid_ anything, and the
|
// op_stall will be false, dcdX_stall will be false, thus we can simply
|
// op_stall will be false, dcdX_stall will be false, thus we can simply
|
// do a ...
|
// do a ...
|
assign dcd_stalled = 1'b0;
|
assign dcd_stalled = 1'b0;
|
`endif
|
`endif
|
//
|
//
|
// PIPELINE STAGE #3 :: Read Operands
|
// PIPELINE STAGE #3 :: Read Operands
|
// Calculate stall conditions
|
// Calculate stall conditions
|
wire op_lock_stall;
|
wire op_lock_stall;
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign op_stall = (opvalid)&&( // Only stall if we're loaded w/validins
|
assign op_stall = (opvalid)&&( // Only stall if we're loaded w/validins
|
// Stall if we're stopped, and not allowed to execute
|
// Stall if we're stopped, and not allowed to execute
|
// an instruction
|
// an instruction
|
// (~master_ce) // Already captured in alu_stall
|
// (~master_ce) // Already captured in alu_stall
|
//
|
//
|
// Stall if going into the ALU and the ALU is stalled
|
// Stall if going into the ALU and the ALU is stalled
|
// i.e. if the memory is busy, or we are single
|
// i.e. if the memory is busy, or we are single
|
// stepping. This also includes our stalls for
|
// stepping. This also includes our stalls for
|
// op_break and op_lock, so we don't need to
|
// op_break and op_lock, so we don't need to
|
// include those as well here.
|
// include those as well here.
|
// This also includes whether or not the divide or
|
// This also includes whether or not the divide or
|
// floating point units are busy.
|
// floating point units are busy.
|
(alu_stall)
|
(alu_stall)
|
//
|
//
|
// Stall if we are going into memory with an operation
|
// Stall if we are going into memory with an operation
|
// that cannot be pipelined, and the memory is
|
// that cannot be pipelined, and the memory is
|
// already busy
|
// already busy
|
||(mem_stalled) // &&(opvalid_mem) part of mem_stalled
|
||(mem_stalled) // &&(opvalid_mem) part of mem_stalled
|
)
|
)
|
||(dcdvalid)&&(
|
||(dcdvalid)&&(
|
// Stall if we need to wait for an operand A
|
// Stall if we need to wait for an operand A
|
// to be ready to read
|
// to be ready to read
|
(dcdA_stall)
|
(dcdA_stall)
|
// Likewise for B, also includes logic
|
// Likewise for B, also includes logic
|
// regarding immediate offset (register must
|
// regarding immediate offset (register must
|
// be in register file if we need to add to
|
// be in register file if we need to add to
|
// an immediate)
|
// an immediate)
|
||(dcdB_stall)
|
||(dcdB_stall)
|
// Or if we need to wait on flags to work on the
|
// Or if we need to wait on flags to work on the
|
// CC register
|
// CC register
|
||(dcdF_stall)
|
||(dcdF_stall)
|
);
|
);
|
assign op_ce = ((dcdvalid)||(dcd_illegal))&&(~op_stall)&&(~clear_pipeline);
|
assign op_ce = ((dcdvalid)||(dcd_illegal))&&(~op_stall)&&(~clear_pipeline);
|
`else
|
`else
|
assign op_stall = (opvalid)&&(~master_ce);
|
assign op_stall = (opvalid)&&(~master_ce);
|
assign op_ce = ((dcdvalid)||(dcd_illegal));
|
assign op_ce = ((dcdvalid)||(dcd_illegal));
|
`endif
|
`endif
|
|
|
//
|
//
|
// PIPELINE STAGE #4 :: ALU / Memory
|
// PIPELINE STAGE #4 :: ALU / Memory
|
// Calculate stall conditions
|
// Calculate stall conditions
|
//
|
//
|
// 1. Basic stall is if the previous stage is valid and the next is
|
// 1. Basic stall is if the previous stage is valid and the next is
|
// busy.
|
// busy.
|
// 2. Also stall if the prior stage is valid and the master clock enable
|
// 2. Also stall if the prior stage is valid and the master clock enable
|
// is de-selected
|
// is de-selected
|
// 3. Stall if someone on the other end is writing the CC register,
|
// 3. Stall if someone on the other end is writing the CC register,
|
// since we don't know if it'll put us to sleep or not.
|
// since we don't know if it'll put us to sleep or not.
|
// 4. Last case: Stall if we would otherwise move a break instruction
|
// 4. Last case: Stall if we would otherwise move a break instruction
|
// through the ALU. Break instructions are not allowed through
|
// through the ALU. Break instructions are not allowed through
|
// the ALU.
|
// the ALU.
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign alu_stall = (((~master_ce)||(mem_rdbusy)||(alu_busy))&&(opvalid_alu)) //Case 1&2
|
assign alu_stall = (((~master_ce)||(mem_rdbusy)||(alu_busy))&&(opvalid_alu)) //Case 1&2
|
// Old case #3--this isn't an ALU stall though ...
|
// Old case #3--this isn't an ALU stall though ...
|
||((opvalid_alu)&&(wr_reg_ce)&&(wr_reg_id[4] == op_gie)
|
||((opvalid_alu)&&(wr_reg_ce)&&(wr_reg_id[4] == op_gie)
|
&&(wr_write_cc)) // Case 3
|
&&(wr_write_cc)) // Case 3
|
||((opvalid)&&(op_lock)&&(op_lock_stall))
|
||((opvalid)&&(op_lock)&&(op_lock_stall))
|
||((opvalid)&&(op_break))
|
||((opvalid)&&(op_break))
|
||(div_busy)||(fpu_busy);
|
||(div_busy)||(fpu_busy);
|
assign alu_ce = (master_ce)&&((opvalid_alu)||(op_illegal))
|
assign alu_ce = (master_ce)&&((opvalid_alu)||(op_illegal))
|
&&(~alu_stall)
|
&&(~alu_stall)
|
&&(~clear_pipeline);
|
&&(~clear_pipeline);
|
`else
|
`else
|
assign alu_stall = ((~master_ce)&&(opvalid_alu))
|
assign alu_stall = ((~master_ce)&&(opvalid_alu))
|
||((opvalid_alu)&&(op_break));
|
||((opvalid_alu)&&(op_break));
|
assign alu_ce = (master_ce)&&((opvalid_alu)||(op_illegal))&&(~alu_stall);
|
assign alu_ce = (master_ce)&&((opvalid_alu)||(op_illegal))&&(~alu_stall);
|
`endif
|
`endif
|
//
|
//
|
|
|
//
|
//
|
// Note: if you change the conditions for mem_ce, you must also change
|
// Note: if you change the conditions for mem_ce, you must also change
|
// alu_pc_valid.
|
// alu_pc_valid.
|
//
|
//
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign mem_ce = (master_ce)&&(opvalid_mem)&&(~mem_stalled)
|
assign mem_ce = (master_ce)&&(opvalid_mem)&&(~mem_stalled)
|
&&(~clear_pipeline);
|
&&(~clear_pipeline);
|
`else
|
`else
|
// If we aren't pipelined, then no one will be changing what's in the
|
// If we aren't pipelined, then no one will be changing what's in the
|
// pipeline (i.e. clear_pipeline), while our only instruction goes
|
// pipeline (i.e. clear_pipeline), while our only instruction goes
|
// through the ... pipeline.
|
// through the ... pipeline.
|
assign mem_ce = (master_ce)&&(opvalid_mem)&&(~mem_stalled);
|
assign mem_ce = (master_ce)&&(opvalid_mem)&&(~mem_stalled);
|
`endif
|
`endif
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
assign mem_stalled = (~master_ce)||(alu_busy)||((opvalid_mem)&&(
|
assign mem_stalled = (~master_ce)||(alu_busy)||((opvalid_mem)&&(
|
(mem_pipe_stalled)
|
(mem_pipe_stalled)
|
||((~op_pipe)&&(mem_busy))
|
||((~op_pipe)&&(mem_busy))
|
||(div_busy)
|
||(div_busy)
|
||(fpu_busy)
|
||(fpu_busy)
|
// Stall waiting for flags to be valid
|
// Stall waiting for flags to be valid
|
// Or waiting for a write to the PC register
|
// Or waiting for a write to the PC register
|
// Or CC register, since that can change the
|
// Or CC register, since that can change the
|
// PC as well
|
// PC as well
|
||((wr_reg_ce)&&(wr_reg_id[4] == op_gie)
|
||((wr_reg_ce)&&(wr_reg_id[4] == op_gie)
|
&&((wr_write_pc)||(wr_write_cc)))));
|
&&((wr_write_pc)||(wr_write_cc)))));
|
`else
|
`else
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign mem_stalled = (mem_busy)||((opvalid_mem)&&(
|
assign mem_stalled = (mem_busy)||((opvalid_mem)&&(
|
(~master_ce)
|
(~master_ce)
|
// Stall waiting for flags to be valid
|
// Stall waiting for flags to be valid
|
// Or waiting for a write to the PC register
|
// Or waiting for a write to the PC register
|
// Or CC register, since that can change the
|
// Or CC register, since that can change the
|
// PC as well
|
// PC as well
|
||((wr_reg_ce)&&(wr_reg_id[4] == op_gie)&&((wr_write_pc)||(wr_write_cc)))));
|
||((wr_reg_ce)&&(wr_reg_id[4] == op_gie)&&((wr_write_pc)||(wr_write_cc)))));
|
`else
|
`else
|
assign mem_stalled = (opvalid_mem)&&(~master_ce);
|
assign mem_stalled = (opvalid_mem)&&(~master_ce);
|
`endif
|
`endif
|
`endif
|
`endif
|
|
|
|
|
//
|
//
|
//
|
//
|
// PIPELINE STAGE #1 :: Prefetch
|
// PIPELINE STAGE #1 :: Prefetch
|
//
|
//
|
//
|
//
|
`ifdef OPT_SINGLE_FETCH
|
`ifdef OPT_SINGLE_FETCH
|
wire pf_ce;
|
wire pf_ce;
|
|
|
assign pf_ce = (~pf_valid)&&(~dcdvalid)&&(~opvalid)&&(~alu_valid);
|
assign pf_ce = (~pf_valid)&&(~dcdvalid)&&(~opvalid)&&(~alu_valid);
|
prefetch #(ADDRESS_WIDTH)
|
prefetch #(ADDRESS_WIDTH)
|
pf(i_clk, i_rst, (pf_ce), (~dcd_stalled), pf_pc, gie,
|
pf(i_clk, i_rst, (pf_ce), (~dcd_stalled), pf_pc, gie,
|
instruction, instruction_pc, instruction_gie,
|
instruction, instruction_pc, instruction_gie,
|
pf_valid, pf_illegal,
|
pf_valid, pf_illegal,
|
pf_cyc, pf_stb, pf_we, pf_addr, pf_data,
|
pf_cyc, pf_stb, pf_we, pf_addr, pf_data,
|
pf_ack, pf_stall, pf_err, i_wb_data);
|
pf_ack, pf_stall, pf_err, i_wb_data);
|
|
|
initial r_dcdvalid = 1'b0;
|
initial r_dcdvalid = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_dcdvalid <= 1'b0;
|
r_dcdvalid <= 1'b0;
|
else if (dcd_ce)
|
else if (dcd_ce)
|
r_dcdvalid <= (pf_valid);
|
r_dcdvalid <= (pf_valid);
|
else if (op_ce)
|
else if (op_ce)
|
r_dcdvalid <= 1'b0;
|
r_dcdvalid <= 1'b0;
|
assign dcdvalid = r_dcdvalid;
|
assign dcdvalid = r_dcdvalid;
|
|
|
`else // Pipe fetch
|
`else // Pipe fetch
|
|
|
`ifdef OPT_TRADITIONAL_PFCACHE
|
`ifdef OPT_TRADITIONAL_PFCACHE
|
pfcache #(LGICACHE, ADDRESS_WIDTH)
|
pfcache #(LGICACHE, ADDRESS_WIDTH)
|
pf(i_clk, i_rst, (new_pc)||((dcd_early_branch)&&(~clear_pipeline)),
|
pf(i_clk, i_rst, (new_pc)||((dcd_early_branch)&&(~clear_pipeline)),
|
i_clear_pf_cache,
|
i_clear_pf_cache,
|
// dcd_pc,
|
// dcd_pc,
|
~dcd_stalled,
|
~dcd_stalled,
|
((dcd_early_branch)&&(~clear_pipeline))
|
((dcd_early_branch)&&(~clear_pipeline))
|
? dcd_branch_pc:pf_pc,
|
? dcd_branch_pc:pf_pc,
|
instruction, instruction_pc, pf_valid,
|
instruction, instruction_pc, pf_valid,
|
pf_cyc, pf_stb, pf_we, pf_addr, pf_data,
|
pf_cyc, pf_stb, pf_we, pf_addr, pf_data,
|
pf_ack, pf_stall, pf_err, i_wb_data,
|
pf_ack, pf_stall, pf_err, i_wb_data,
|
pf_illegal);
|
pf_illegal);
|
`else
|
`else
|
pipefetch #(RESET_ADDRESS, LGICACHE, ADDRESS_WIDTH)
|
pipefetch #(RESET_ADDRESS, LGICACHE, ADDRESS_WIDTH)
|
pf(i_clk, i_rst, (new_pc)||((dcd_early_branch)&&(~clear_pipeline)),
|
pf(i_clk, i_rst, (new_pc)||((dcd_early_branch)&&(~clear_pipeline)),
|
i_clear_pf_cache, ~dcd_stalled,
|
i_clear_pf_cache, ~dcd_stalled,
|
(new_pc)?pf_pc:dcd_branch_pc,
|
(new_pc)?pf_pc:dcd_branch_pc,
|
instruction, instruction_pc, pf_valid,
|
instruction, instruction_pc, pf_valid,
|
pf_cyc, pf_stb, pf_we, pf_addr, pf_data,
|
pf_cyc, pf_stb, pf_we, pf_addr, pf_data,
|
pf_ack, pf_stall, pf_err, i_wb_data,
|
pf_ack, pf_stall, pf_err, i_wb_data,
|
//`ifdef OPT_PRECLEAR_BUS
|
//`ifdef OPT_PRECLEAR_BUS
|
//((dcd_clear_bus)&&(dcdvalid))
|
//((dcd_clear_bus)&&(dcdvalid))
|
//||((op_clear_bus)&&(opvalid))
|
//||((op_clear_bus)&&(opvalid))
|
//||
|
//||
|
//`endif
|
//`endif
|
(mem_cyc_lcl)||(mem_cyc_gbl),
|
(mem_cyc_lcl)||(mem_cyc_gbl),
|
pf_illegal);
|
pf_illegal);
|
`endif
|
`endif
|
assign instruction_gie = gie;
|
assign instruction_gie = gie;
|
|
|
initial r_dcdvalid = 1'b0;
|
initial r_dcdvalid = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(clear_pipeline))
|
if ((i_rst)||(clear_pipeline))
|
r_dcdvalid <= 1'b0;
|
r_dcdvalid <= 1'b0;
|
else if (dcd_ce)
|
else if (dcd_ce)
|
r_dcdvalid <= (pf_valid)&&(~clear_pipeline)&&(~dcd_ljmp)&&((~r_dcdvalid)||(~dcd_early_branch));
|
r_dcdvalid <= (pf_valid)&&(~clear_pipeline)&&(~dcd_ljmp)&&((~r_dcdvalid)||(~dcd_early_branch));
|
else if (op_ce)
|
else if (op_ce)
|
r_dcdvalid <= 1'b0;
|
r_dcdvalid <= 1'b0;
|
assign dcdvalid = r_dcdvalid;
|
assign dcdvalid = r_dcdvalid;
|
`endif
|
`endif
|
|
|
`ifdef OPT_NEW_INSTRUCTION_SET
|
`ifdef OPT_NEW_INSTRUCTION_SET
|
idecode #(AW, IMPLEMENT_MPY, EARLY_BRANCHING, IMPLEMENT_DIVIDE,
|
idecode #(AW, IMPLEMENT_MPY, EARLY_BRANCHING, IMPLEMENT_DIVIDE,
|
IMPLEMENT_FPU)
|
IMPLEMENT_FPU)
|
instruction_decoder(i_clk, (i_rst)||(clear_pipeline),
|
instruction_decoder(i_clk, (i_rst)||(clear_pipeline),
|
dcd_ce, dcd_stalled, instruction, instruction_gie,
|
dcd_ce, dcd_stalled, instruction, instruction_gie,
|
instruction_pc, pf_valid, pf_illegal, dcd_phase,
|
instruction_pc, pf_valid, pf_illegal, dcd_phase,
|
dcd_illegal, dcd_pc, dcd_gie,
|
dcd_illegal, dcd_pc, dcd_gie,
|
{ dcdR_cc, dcdR_pc, dcdR },
|
{ dcdR_cc, dcdR_pc, dcdR },
|
{ dcdA_cc, dcdA_pc, dcdA },
|
{ dcdA_cc, dcdA_pc, dcdA },
|
{ dcdB_cc, dcdB_pc, dcdB },
|
{ dcdB_cc, dcdB_pc, dcdB },
|
dcdI, dcd_zI, dcdF, dcdF_wr, dcdOp,
|
dcdI, dcd_zI, dcdF, dcdF_wr, dcdOp,
|
dcdALU, dcdM, dcdDV, dcdFP, dcd_break, dcd_lock,
|
dcdALU, dcdM, dcdDV, dcdFP, dcd_break, dcd_lock,
|
dcdR_wr,dcdA_rd, dcdB_rd,
|
dcdR_wr,dcdA_rd, dcdB_rd,
|
dcd_early_branch,
|
dcd_early_branch,
|
dcd_branch_pc, dcd_ljmp,
|
dcd_branch_pc, dcd_ljmp,
|
dcd_pipe);
|
dcd_pipe);
|
`else
|
`else
|
idecode_deprecated
|
idecode_deprecated
|
#(AW, IMPLEMENT_MPY, EARLY_BRANCHING, IMPLEMENT_DIVIDE,
|
#(AW, IMPLEMENT_MPY, EARLY_BRANCHING, IMPLEMENT_DIVIDE,
|
IMPLEMENT_FPU)
|
IMPLEMENT_FPU)
|
instruction_decoder(i_clk, (i_rst)||(clear_pipeline),
|
instruction_decoder(i_clk, (i_rst)||(clear_pipeline),
|
dcd_ce, dcd_stalled, instruction, instruction_gie,
|
dcd_ce, dcd_stalled, instruction, instruction_gie,
|
instruction_pc, pf_valid, pf_illegal, dcd_phase,
|
instruction_pc, pf_valid, pf_illegal, dcd_phase,
|
dcd_illegal, dcd_pc, dcd_gie,
|
dcd_illegal, dcd_pc, dcd_gie,
|
{ dcdR_cc, dcdR_pc, dcdR },
|
{ dcdR_cc, dcdR_pc, dcdR },
|
{ dcdA_cc, dcdA_pc, dcdA },
|
{ dcdA_cc, dcdA_pc, dcdA },
|
{ dcdB_cc, dcdB_pc, dcdB },
|
{ dcdB_cc, dcdB_pc, dcdB },
|
dcdI, dcd_zI, dcdF, dcdF_wr, dcdOp,
|
dcdI, dcd_zI, dcdF, dcdF_wr, dcdOp,
|
dcdALU, dcdM, dcdDV, dcdFP, dcd_break, dcd_lock,
|
dcdALU, dcdM, dcdDV, dcdFP, dcd_break, dcd_lock,
|
dcdR_wr,dcdA_rd, dcdB_rd,
|
dcdR_wr,dcdA_rd, dcdB_rd,
|
dcd_early_branch,
|
dcd_early_branch,
|
dcd_branch_pc,
|
dcd_branch_pc,
|
dcd_pipe);
|
dcd_pipe);
|
assign dcd_ljmp = 1'b0;
|
assign dcd_ljmp = 1'b0;
|
`endif
|
`endif
|
|
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
reg r_op_pipe;
|
reg r_op_pipe;
|
|
|
initial r_op_pipe = 1'b0;
|
initial r_op_pipe = 1'b0;
|
// To be a pipeable operation, there must be
|
// To be a pipeable operation, there must be
|
// two valid adjacent instructions
|
// two valid adjacent instructions
|
// Both must be memory instructions
|
// Both must be memory instructions
|
// Both must be writes, or both must be reads
|
// Both must be writes, or both must be reads
|
// Both operations must be to the same identical address,
|
// Both operations must be to the same identical address,
|
// or at least a single (one) increment above that address
|
// or at least a single (one) increment above that address
|
//
|
//
|
// However ... we need to know this before this clock, hence this is
|
// However ... we need to know this before this clock, hence this is
|
// calculated in the instruction decoder.
|
// calculated in the instruction decoder.
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce)
|
if (op_ce)
|
r_op_pipe <= dcd_pipe;
|
r_op_pipe <= dcd_pipe;
|
assign op_pipe = r_op_pipe;
|
assign op_pipe = r_op_pipe;
|
`else
|
`else
|
assign op_pipe = 1'b0;
|
assign op_pipe = 1'b0;
|
`endif
|
`endif
|
|
|
//
|
//
|
//
|
//
|
// PIPELINE STAGE #3 :: Read Operands (Registers)
|
// PIPELINE STAGE #3 :: Read Operands (Registers)
|
//
|
//
|
//
|
//
|
assign w_opA = regset[dcdA];
|
assign w_opA = regset[dcdA];
|
assign w_opB = regset[dcdB];
|
assign w_opB = regset[dcdB];
|
|
|
wire [8:0] w_cpu_info;
|
wire [8:0] w_cpu_info;
|
assign w_cpu_info = {
|
assign w_cpu_info = {
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_MULTIPLY
|
`ifdef OPT_MULTIPLY
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_DIVIDE
|
`ifdef OPT_DIVIDE
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_IMPLEMENT_FPU
|
`ifdef OPT_IMPLEMENT_FPU
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_TRADITIONAL_CACHE
|
`ifdef OPT_TRADITIONAL_CACHE
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_EARLY_BRANCHING
|
`ifdef OPT_EARLY_BRANCHING
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
1'b1,
|
1'b1,
|
`else
|
`else
|
1'b0,
|
1'b0,
|
`endif
|
`endif
|
`ifdef OPT_VLIW
|
`ifdef OPT_VLIW
|
1'b1
|
1'b1
|
`else
|
`else
|
1'b0
|
1'b0
|
`endif
|
`endif
|
};
|
};
|
|
|
wire [31:0] w_pcA_v;
|
wire [31:0] w_pcA_v;
|
generate
|
generate
|
if (AW < 32)
|
if (AW < 32)
|
assign w_pcA_v = {{(32-AW){1'b0}}, (dcdA[4] == dcd_gie)?dcd_pc:upc };
|
assign w_pcA_v = {{(32-AW){1'b0}}, (dcdA[4] == dcd_gie)?dcd_pc:upc };
|
else
|
else
|
assign w_pcA_v = (dcdA[4] == dcd_gie)?dcd_pc:upc;
|
assign w_pcA_v = (dcdA[4] == dcd_gie)?dcd_pc:upc;
|
endgenerate
|
endgenerate
|
|
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
reg [4:0] opA_id, opB_id;
|
reg [4:0] opA_id, opB_id;
|
reg opA_rd, opB_rd;
|
reg opA_rd, opB_rd;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce)
|
if (op_ce)
|
begin
|
begin
|
opA_id <= dcdA;
|
opA_id <= dcdA;
|
opB_id <= dcdB;
|
opB_id <= dcdB;
|
opA_rd <= dcdA_rd;
|
opA_rd <= dcdA_rd;
|
opB_rd <= dcdB_rd;
|
opB_rd <= dcdB_rd;
|
end
|
end
|
`endif
|
`endif
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce) // &&(dcdvalid))
|
if (op_ce) // &&(dcdvalid))
|
begin
|
begin
|
if ((wr_reg_ce)&&(wr_reg_id == dcdA))
|
if ((wr_reg_ce)&&(wr_reg_id == dcdA))
|
r_opA <= wr_reg_vl;
|
r_opA <= wr_reg_vl;
|
else if (dcdA_pc)
|
else if (dcdA_pc)
|
r_opA <= w_pcA_v;
|
r_opA <= w_pcA_v;
|
else if (dcdA_cc)
|
else if (dcdA_cc)
|
r_opA <= { w_cpu_info, w_opA[22:14], (dcdA[4])?w_uflags:w_iflags };
|
r_opA <= { w_cpu_info, w_opA[22:14], (dcdA[4])?w_uflags:w_iflags };
|
else
|
else
|
r_opA <= w_opA;
|
r_opA <= w_opA;
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
end else
|
end else
|
begin // We were going to pick these up when they became valid,
|
begin // We were going to pick these up when they became valid,
|
// but for some reason we're stuck here as they became
|
// but for some reason we're stuck here as they became
|
// valid. Pick them up now anyway
|
// valid. Pick them up now anyway
|
// if (((opA_alu)&&(alu_wr))||((opA_mem)&&(mem_valid)))
|
// if (((opA_alu)&&(alu_wr))||((opA_mem)&&(mem_valid)))
|
// r_opA <= wr_reg_vl;
|
// r_opA <= wr_reg_vl;
|
if ((wr_reg_ce)&&(wr_reg_id == opA_id)&&(opA_rd))
|
if ((wr_reg_ce)&&(wr_reg_id == opA_id)&&(opA_rd))
|
r_opA <= wr_reg_vl;
|
r_opA <= wr_reg_vl;
|
`endif
|
`endif
|
end
|
end
|
|
|
wire [31:0] w_opBnI, w_pcB_v;
|
wire [31:0] w_opBnI, w_pcB_v;
|
generate
|
generate
|
if (AW < 32)
|
if (AW < 32)
|
assign w_pcB_v = {{(32-AW){1'b0}}, (dcdB[4] == dcd_gie)?dcd_pc:upc };
|
assign w_pcB_v = {{(32-AW){1'b0}}, (dcdB[4] == dcd_gie)?dcd_pc:upc };
|
else
|
else
|
assign w_pcB_v = (dcdB[4] == dcd_gie)?dcd_pc:upc;
|
assign w_pcB_v = (dcdB[4] == dcd_gie)?dcd_pc:upc;
|
endgenerate
|
endgenerate
|
|
|
assign w_opBnI = (~dcdB_rd) ? 32'h00
|
assign w_opBnI = (~dcdB_rd) ? 32'h00
|
: (((wr_reg_ce)&&(wr_reg_id == dcdB)) ? wr_reg_vl
|
: (((wr_reg_ce)&&(wr_reg_id == dcdB)) ? wr_reg_vl
|
: ((dcdB_pc) ? w_pcB_v
|
: ((dcdB_pc) ? w_pcB_v
|
: ((dcdB_cc) ? { w_cpu_info, w_opB[22:14], // w_opB[31:14],
|
: ((dcdB_cc) ? { w_cpu_info, w_opB[22:14], // w_opB[31:14],
|
(dcdB[4])?w_uflags:w_iflags}
|
(dcdB[4])?w_uflags:w_iflags}
|
: w_opB)));
|
: w_opB)));
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce) // &&(dcdvalid))
|
if (op_ce) // &&(dcdvalid))
|
r_opB <= w_opBnI + dcdI;
|
r_opB <= w_opBnI + dcdI;
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
else if ((wr_reg_ce)&&(opB_id == wr_reg_id)&&(opB_rd))
|
else if ((wr_reg_ce)&&(opB_id == wr_reg_id)&&(opB_rd))
|
r_opB <= wr_reg_vl;
|
r_opB <= wr_reg_vl;
|
`endif
|
`endif
|
|
|
// The logic here has become more complex than it should be, no thanks
|
// The logic here has become more complex than it should be, no thanks
|
// to Xilinx's Vivado trying to help. The conditions are supposed to
|
// to Xilinx's Vivado trying to help. The conditions are supposed to
|
// be two sets of four bits: the top bits specify what bits matter, the
|
// be two sets of four bits: the top bits specify what bits matter, the
|
// bottom specify what those top bits must equal. However, two of
|
// bottom specify what those top bits must equal. However, two of
|
// conditions check whether bits are on, and those are the only two
|
// conditions check whether bits are on, and those are the only two
|
// conditions checking those bits. Therefore, Vivado complains that
|
// conditions checking those bits. Therefore, Vivado complains that
|
// these two bits are redundant. Hence the convoluted expression
|
// these two bits are redundant. Hence the convoluted expression
|
// below, arriving at what we finally want in the (now wire net)
|
// below, arriving at what we finally want in the (now wire net)
|
// opF.
|
// opF.
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce)
|
if (op_ce)
|
begin // Set the flag condition codes, bit order is [3:0]=VNCZ
|
begin // Set the flag condition codes, bit order is [3:0]=VNCZ
|
case(dcdF[2:0])
|
case(dcdF[2:0])
|
3'h0: r_opF <= 6'h00; // Always
|
3'h0: r_opF <= 6'h00; // Always
|
`ifdef OPT_NEW_INSTRUCTION_SET
|
`ifdef OPT_NEW_INSTRUCTION_SET
|
// These were remapped as part of the new instruction
|
// These were remapped as part of the new instruction
|
// set in order to make certain that the low order
|
// set in order to make certain that the low order
|
// two bits contained the most commonly used
|
// two bits contained the most commonly used
|
// conditions: Always, LT, Z, and NZ.
|
// conditions: Always, LT, Z, and NZ.
|
3'h1: r_opF <= 6'h24; // LT
|
3'h1: r_opF <= 6'h24; // LT
|
3'h2: r_opF <= 6'h11; // Z
|
3'h2: r_opF <= 6'h11; // Z
|
3'h3: r_opF <= 6'h10; // NE
|
3'h3: r_opF <= 6'h10; // NE
|
3'h4: r_opF <= 6'h30; // GT (!N&!Z)
|
3'h4: r_opF <= 6'h30; // GT (!N&!Z)
|
3'h5: r_opF <= 6'h20; // GE (!N)
|
3'h5: r_opF <= 6'h20; // GE (!N)
|
`else
|
`else
|
3'h1: r_opF <= 6'h11; // Z
|
3'h1: r_opF <= 6'h11; // Z
|
3'h2: r_opF <= 6'h10; // NE
|
3'h2: r_opF <= 6'h10; // NE
|
3'h3: r_opF <= 6'h20; // GE (!N)
|
3'h3: r_opF <= 6'h20; // GE (!N)
|
3'h4: r_opF <= 6'h30; // GT (!N&!Z)
|
3'h4: r_opF <= 6'h30; // GT (!N&!Z)
|
3'h5: r_opF <= 6'h24; // LT
|
3'h5: r_opF <= 6'h24; // LT
|
`endif
|
`endif
|
3'h6: r_opF <= 6'h02; // C
|
3'h6: r_opF <= 6'h02; // C
|
3'h7: r_opF <= 6'h08; // V
|
3'h7: r_opF <= 6'h08; // V
|
endcase
|
endcase
|
end // Bit order is { (flags_not_used), VNCZ mask, VNCZ value }
|
end // Bit order is { (flags_not_used), VNCZ mask, VNCZ value }
|
assign opF = { r_opF[3], r_opF[5], r_opF[1], r_opF[4:0] };
|
assign opF = { r_opF[3], r_opF[5], r_opF[1], r_opF[4:0] };
|
|
|
wire w_opvalid;
|
wire w_opvalid;
|
assign w_opvalid = (~clear_pipeline)&&(dcdvalid)&&(~dcd_ljmp);
|
assign w_opvalid = (~clear_pipeline)&&(dcdvalid)&&(~dcd_ljmp);
|
initial opvalid = 1'b0;
|
initial opvalid = 1'b0;
|
initial opvalid_alu = 1'b0;
|
initial opvalid_alu = 1'b0;
|
initial opvalid_mem = 1'b0;
|
initial opvalid_mem = 1'b0;
|
initial opvalid_div = 1'b0;
|
initial opvalid_div = 1'b0;
|
initial opvalid_fpu = 1'b0;
|
initial opvalid_fpu = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
begin
|
begin
|
opvalid <= 1'b0;
|
opvalid <= 1'b0;
|
opvalid_alu <= 1'b0;
|
opvalid_alu <= 1'b0;
|
opvalid_mem <= 1'b0;
|
opvalid_mem <= 1'b0;
|
end else if (op_ce)
|
end else if (op_ce)
|
begin
|
begin
|
// Do we have a valid instruction?
|
// Do we have a valid instruction?
|
// The decoder may vote to stall one of its
|
// The decoder may vote to stall one of its
|
// instructions based upon something we currently
|
// instructions based upon something we currently
|
// have in our queue. This instruction must then
|
// have in our queue. This instruction must then
|
// move forward, and get a stall cycle inserted.
|
// move forward, and get a stall cycle inserted.
|
// Hence, the test on dcd_stalled here. If we must
|
// Hence, the test on dcd_stalled here. If we must
|
// wait until our operands are valid, then we aren't
|
// wait until our operands are valid, then we aren't
|
// valid yet until then.
|
// valid yet until then.
|
opvalid<= w_opvalid;
|
opvalid<= w_opvalid;
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
opvalid_alu <= ((dcdALU)||(dcd_illegal))&&(w_opvalid);
|
opvalid_alu <= ((dcdALU)||(dcd_illegal))&&(w_opvalid);
|
opvalid_mem <= (dcdM)&&(~dcd_illegal)&&(w_opvalid);
|
opvalid_mem <= (dcdM)&&(~dcd_illegal)&&(w_opvalid);
|
opvalid_div <= (dcdDV)&&(~dcd_illegal)&&(w_opvalid);
|
opvalid_div <= (dcdDV)&&(~dcd_illegal)&&(w_opvalid);
|
opvalid_fpu <= (dcdFP)&&(~dcd_illegal)&&(w_opvalid);
|
opvalid_fpu <= (dcdFP)&&(~dcd_illegal)&&(w_opvalid);
|
`else
|
`else
|
opvalid_alu <= (dcdALU)&&(w_opvalid);
|
opvalid_alu <= (dcdALU)&&(w_opvalid);
|
opvalid_mem <= (dcdM)&&(w_opvalid);
|
opvalid_mem <= (dcdM)&&(w_opvalid);
|
opvalid_div <= (dcdDV)&&(w_opvalid);
|
opvalid_div <= (dcdDV)&&(w_opvalid);
|
opvalid_fpu <= (dcdFP)&&(w_opvalid);
|
opvalid_fpu <= (dcdFP)&&(w_opvalid);
|
`endif
|
`endif
|
end else if ((clear_pipeline)||(alu_ce)||(mem_ce)||(div_ce)||(fpu_ce))
|
end else if ((clear_pipeline)||(alu_ce)||(mem_ce)||(div_ce)||(fpu_ce))
|
begin
|
begin
|
opvalid <= 1'b0;
|
opvalid <= 1'b0;
|
opvalid_alu <= 1'b0;
|
opvalid_alu <= 1'b0;
|
opvalid_mem <= 1'b0;
|
opvalid_mem <= 1'b0;
|
opvalid_div <= 1'b0;
|
opvalid_div <= 1'b0;
|
opvalid_fpu <= 1'b0;
|
opvalid_fpu <= 1'b0;
|
end
|
end
|
|
|
// Here's part of our debug interface. When we recognize a break
|
// Here's part of our debug interface. When we recognize a break
|
// instruction, we set the op_break flag. That'll prevent this
|
// instruction, we set the op_break flag. That'll prevent this
|
// instruction from entering the ALU, and cause an interrupt before
|
// instruction from entering the ALU, and cause an interrupt before
|
// this instruction. Thus, returning to this code will cause the
|
// this instruction. Thus, returning to this code will cause the
|
// break to repeat and continue upon return. To get out of this
|
// break to repeat and continue upon return. To get out of this
|
// condition, replace the break instruction with what it is supposed
|
// condition, replace the break instruction with what it is supposed
|
// to be, step through it, and then replace it back. In this fashion,
|
// to be, step through it, and then replace it back. In this fashion,
|
// a debugger can step through code.
|
// a debugger can step through code.
|
// assign w_op_break = (dcd_break)&&(r_dcdI[15:0] == 16'h0001);
|
// assign w_op_break = (dcd_break)&&(r_dcdI[15:0] == 16'h0001);
|
initial op_break = 1'b0;
|
initial op_break = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst) op_break <= 1'b0;
|
if (i_rst) op_break <= 1'b0;
|
else if (op_ce) op_break <= (dcd_break);
|
else if (op_ce) op_break <= (dcd_break);
|
else if ((clear_pipeline)||(~opvalid))
|
else if ((clear_pipeline)||(~opvalid))
|
op_break <= 1'b0;
|
op_break <= 1'b0;
|
|
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
generate
|
generate
|
if (IMPLEMENT_LOCK != 0)
|
if (IMPLEMENT_LOCK != 0)
|
begin
|
begin
|
reg r_op_lock, r_op_lock_stall;
|
reg r_op_lock, r_op_lock_stall;
|
|
|
initial r_op_lock_stall = 1'b0;
|
initial r_op_lock_stall = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_op_lock_stall <= 1'b0;
|
r_op_lock_stall <= 1'b0;
|
else
|
else
|
r_op_lock_stall <= (~opvalid)||(~op_lock)
|
r_op_lock_stall <= (~opvalid)||(~op_lock)
|
||(~dcdvalid)||(~pf_valid);
|
||(~dcdvalid)||(~pf_valid);
|
|
|
assign op_lock_stall = r_op_lock_stall;
|
assign op_lock_stall = r_op_lock_stall;
|
|
|
initial r_op_lock = 1'b0;
|
initial r_op_lock = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_op_lock <= 1'b0;
|
r_op_lock <= 1'b0;
|
else if ((op_ce)&&(dcd_lock))
|
else if (op_ce)
|
r_op_lock <= 1'b1;
|
r_op_lock <= (dcd_lock)&&(~clear_pipeline);
|
else if ((op_ce)||(clear_pipeline))
|
|
r_op_lock <= 1'b0;
|
|
assign op_lock = r_op_lock;
|
assign op_lock = r_op_lock;
|
|
|
end else begin
|
end else begin
|
assign op_lock_stall = 1'b0;
|
assign op_lock_stall = 1'b0;
|
assign op_lock = 1'b0;
|
assign op_lock = 1'b0;
|
end endgenerate
|
end endgenerate
|
|
|
`else
|
`else
|
assign op_lock_stall = 1'b0;
|
assign op_lock_stall = 1'b0;
|
assign op_lock = 1'b0;
|
assign op_lock = 1'b0;
|
`endif
|
`endif
|
|
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
initial op_illegal = 1'b0;
|
initial op_illegal = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(clear_pipeline))
|
if ((i_rst)||(clear_pipeline))
|
op_illegal <= 1'b0;
|
op_illegal <= 1'b0;
|
else if(op_ce)
|
else if(op_ce)
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
op_illegal <=(dcd_illegal)||((dcd_lock)&&(IMPLEMENT_LOCK == 0));
|
op_illegal <=(dcd_illegal)||((dcd_lock)&&(IMPLEMENT_LOCK == 0));
|
`else
|
`else
|
op_illegal <= (dcd_illegal)||(dcd_lock);
|
op_illegal <= (dcd_illegal)||(dcd_lock);
|
`endif
|
`endif
|
`endif
|
`endif
|
|
|
// No generate on EARLY_BRANCHING here, since if EARLY_BRANCHING is not
|
// No generate on EARLY_BRANCHING here, since if EARLY_BRANCHING is not
|
// set, dcd_early_branch will simply be a wire connected to zero and
|
// set, dcd_early_branch will simply be a wire connected to zero and
|
// this logic should just optimize.
|
// this logic should just optimize.
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce)
|
if (op_ce)
|
begin
|
begin
|
opF_wr <= (dcdF_wr)&&((~dcdR_cc)||(~dcdR_wr))
|
opF_wr <= (dcdF_wr)&&((~dcdR_cc)||(~dcdR_wr))
|
&&(~dcd_early_branch)&&(~dcd_illegal);
|
&&(~dcd_early_branch)&&(~dcd_illegal);
|
opR_wr <= (dcdR_wr)&&(~dcd_early_branch)&&(~dcd_illegal);
|
opR_wr <= (dcdR_wr)&&(~dcd_early_branch)&&(~dcd_illegal);
|
end
|
end
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (op_ce)
|
if (op_ce)
|
begin
|
begin
|
opn <= dcdOp; // Which ALU operation?
|
opn <= dcdOp; // Which ALU operation?
|
// opM <= dcdM; // Is this a memory operation?
|
// opM <= dcdM; // Is this a memory operation?
|
// What register will these results be written into?
|
// What register will these results be written into?
|
opR <= dcdR;
|
opR <= dcdR;
|
opR_cc <= (dcdR_cc)&&(dcdR_wr)&&(dcdR[4]==dcd_gie);
|
opR_cc <= (dcdR_cc)&&(dcdR_wr)&&(dcdR[4]==dcd_gie);
|
// User level (1), vs supervisor (0)/interrupts disabled
|
// User level (1), vs supervisor (0)/interrupts disabled
|
op_gie <= dcd_gie;
|
op_gie <= dcd_gie;
|
|
|
|
|
//
|
//
|
op_pc <= (dcd_early_branch)?dcd_branch_pc:dcd_pc;
|
op_pc <= (dcd_early_branch)?dcd_branch_pc:dcd_pc;
|
end
|
end
|
assign opFl = (op_gie)?(w_uflags):(w_iflags);
|
assign opFl = (op_gie)?(w_uflags):(w_iflags);
|
|
|
`ifdef OPT_VLIW
|
`ifdef OPT_VLIW
|
reg r_op_phase;
|
reg r_op_phase;
|
initial r_op_phase = 1'b0;
|
initial r_op_phase = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(clear_pipeline))
|
if ((i_rst)||(clear_pipeline))
|
r_op_phase <= 1'b0;
|
r_op_phase <= 1'b0;
|
else if (op_ce)
|
else if (op_ce)
|
r_op_phase <= dcd_phase;
|
r_op_phase <= dcd_phase;
|
assign op_phase = r_op_phase;
|
assign op_phase = r_op_phase;
|
`else
|
`else
|
assign op_phase = 1'b0;
|
assign op_phase = 1'b0;
|
`endif
|
`endif
|
|
|
// This is tricky. First, the PC and Flags registers aren't kept in
|
// This is tricky. First, the PC and Flags registers aren't kept in
|
// register set but in special registers of their own. So step one
|
// register set but in special registers of their own. So step one
|
// is to select the right register. Step to is to replace that
|
// is to select the right register. Step to is to replace that
|
// register with the results of an ALU or memory operation, if such
|
// register with the results of an ALU or memory operation, if such
|
// results are now available. Otherwise, we'd need to insert a wait
|
// results are now available. Otherwise, we'd need to insert a wait
|
// state of some type.
|
// state of some type.
|
//
|
//
|
// The alternative approach would be to define some sort of
|
// The alternative approach would be to define some sort of
|
// op_stall wire, which would stall any upstream stage.
|
// op_stall wire, which would stall any upstream stage.
|
// We'll create a flag here to start our coordination. Once we
|
// We'll create a flag here to start our coordination. Once we
|
// define this flag to something other than just plain zero, then
|
// define this flag to something other than just plain zero, then
|
// the stalls will already be in place.
|
// the stalls will already be in place.
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign opA = ((wr_reg_ce)&&(wr_reg_id == opA_id)) // &&(opA_rd))
|
assign opA = ((wr_reg_ce)&&(wr_reg_id == opA_id)) // &&(opA_rd))
|
? wr_reg_vl : r_opA;
|
? wr_reg_vl : r_opA;
|
`else
|
`else
|
assign opA = r_opA;
|
assign opA = r_opA;
|
`endif
|
`endif
|
|
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
// Stall if we have decoded an instruction that will read register A
|
// Stall if we have decoded an instruction that will read register A
|
// AND ... something that may write a register is running
|
// AND ... something that may write a register is running
|
// AND (series of conditions here ...)
|
// AND (series of conditions here ...)
|
// The operation might set flags, and we wish to read the
|
// The operation might set flags, and we wish to read the
|
// CC register
|
// CC register
|
// OR ... (No other conditions)
|
// OR ... (No other conditions)
|
assign dcdA_stall = (dcdA_rd) // &&(dcdvalid) is checked for elsewhere
|
assign dcdA_stall = (dcdA_rd) // &&(dcdvalid) is checked for elsewhere
|
&&((opvalid)||(mem_rdbusy)
|
&&((opvalid)||(mem_rdbusy)
|
||(div_busy)||(fpu_busy))
|
||(div_busy)||(fpu_busy))
|
&&((opF_wr)&&(dcdA_cc));
|
&&((opF_wr)&&(dcdA_cc));
|
`else
|
`else
|
// There are no pipeline hazards, if we aren't pipelined
|
// There are no pipeline hazards, if we aren't pipelined
|
assign dcdA_stall = 1'b0;
|
assign dcdA_stall = 1'b0;
|
`endif
|
`endif
|
|
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
assign opB = ((wr_reg_ce)&&(wr_reg_id == opB_id)&&(opB_rd))
|
assign opB = ((wr_reg_ce)&&(wr_reg_id == opB_id)&&(opB_rd))
|
? wr_reg_vl: r_opB;
|
? wr_reg_vl: r_opB;
|
`else
|
`else
|
assign opB = r_opB;
|
assign opB = r_opB;
|
`endif
|
`endif
|
|
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
// Stall if we have decoded an instruction that will read register B
|
// Stall if we have decoded an instruction that will read register B
|
// AND ... something that may write a (unknown) register is running
|
// AND ... something that may write a (unknown) register is running
|
// AND (series of conditions here ...)
|
// AND (series of conditions here ...)
|
// The operation might set flags, and we wish to read the
|
// The operation might set flags, and we wish to read the
|
// CC register
|
// CC register
|
// OR the operation might set register B, and we still need
|
// OR the operation might set register B, and we still need
|
// a clock to add the offset to it
|
// a clock to add the offset to it
|
assign dcdB_stall = (dcdB_rd) // &&(dcdvalid) is checked for elsewhere
|
assign dcdB_stall = (dcdB_rd) // &&(dcdvalid) is checked for elsewhere
|
// If the op stage isn't valid, yet something
|
// If the op stage isn't valid, yet something
|
// is running, then it must have been valid.
|
// is running, then it must have been valid.
|
// We'll use the last values from that stage
|
// We'll use the last values from that stage
|
// (opR_wr, opF_wr, opR) in our logic below.
|
// (opR_wr, opF_wr, opR) in our logic below.
|
&&((opvalid)||(mem_rdbusy)
|
&&((opvalid)||(mem_rdbusy)
|
||(div_busy)||(fpu_busy)||(alu_busy))
|
||(div_busy)||(fpu_busy)||(alu_busy))
|
&&(
|
&&(
|
// Stall on memory ops writing to my register
|
// Stall on memory ops writing to my register
|
// (i.e. loads), or on any write to my
|
// (i.e. loads), or on any write to my
|
// register if I have an immediate offset
|
// register if I have an immediate offset
|
// Actually, this is worse. I can't tell
|
// Actually, this is worse. I can't tell
|
// whether or not my register is going to
|
// whether or not my register is going to
|
// be written to, so
|
// be written to, so
|
// Note the exception for writing to the PC:
|
// Note the exception for writing to the PC:
|
// if I write to the PC, the whole next
|
// if I write to the PC, the whole next
|
// instruction is invalid, not just the
|
// instruction is invalid, not just the
|
// operand. That'll get wiped in the
|
// operand. That'll get wiped in the
|
// next operation anyway, so don't stall
|
// next operation anyway, so don't stall
|
// here. This keeps a BC X, BNZ Y from
|
// here. This keeps a BC X, BNZ Y from
|
// stalling between the two branches.
|
// stalling between the two branches.
|
// BC X, BRA Y is still clear, since BRA Y
|
// BC X, BRA Y is still clear, since BRA Y
|
// is an early branch instruction.
|
// is an early branch instruction.
|
// (This exception is commented out in
|
// (This exception is commented out in
|
// order to help keep our logic simple, and
|
// order to help keep our logic simple, and
|
// because multiple conditional branches
|
// because multiple conditional branches
|
// following each other constitutes a
|
// following each other constitutes a
|
// fairly unusualy code structure.)
|
// fairly unusualy code structure.)
|
//
|
//
|
((~dcd_zI)&&(
|
((~dcd_zI)&&(
|
((opR == dcdB)&&(opR_wr))
|
((opR == dcdB)&&(opR_wr))
|
||(((opvalid_mem)||(mem_rdbusy))
|
||(((opvalid_mem)||(mem_rdbusy))
|
&&(op_pipe))))
|
&&(op_pipe))))
|
// Stall following any instruction that will
|
// Stall following any instruction that will
|
// set the flags, if we're going to need the
|
// set the flags, if we're going to need the
|
// flags (CC) register for opB.
|
// flags (CC) register for opB.
|
||((opF_wr)&&(dcdB_cc))
|
||((opF_wr)&&(dcdB_cc))
|
// Stall on any ongoing memory operation that
|
// Stall on any ongoing memory operation that
|
// will write to opB -- captured above
|
// will write to opB -- captured above
|
// ||((mem_busy)&&(~mem_we)&&(mem_last_reg==dcdB)&&(~dcd_zI))
|
// ||((mem_busy)&&(~mem_we)&&(mem_last_reg==dcdB)&&(~dcd_zI))
|
);
|
);
|
assign dcdF_stall = ((~dcdF[3])
|
assign dcdF_stall = ((~dcdF[3])
|
||((dcdA_rd)&&(dcdA_cc))
|
||((dcdA_rd)&&(dcdA_cc))
|
||((dcdB_rd)&&(dcdB_cc)))
|
||((dcdB_rd)&&(dcdB_cc)))
|
&&(opvalid)&&(opR_cc);
|
&&(opvalid)&&(opR_cc);
|
// &&(dcdvalid) is checked for elsewhere
|
// &&(dcdvalid) is checked for elsewhere
|
`else
|
`else
|
// No stalls without pipelining, 'cause how can you have a pipeline
|
// No stalls without pipelining, 'cause how can you have a pipeline
|
// hazard without the pipeline?
|
// hazard without the pipeline?
|
assign dcdB_stall = 1'b0;
|
assign dcdB_stall = 1'b0;
|
assign dcdF_stall = 1'b0;
|
assign dcdF_stall = 1'b0;
|
`endif
|
`endif
|
//
|
//
|
//
|
//
|
// PIPELINE STAGE #4 :: Apply Instruction
|
// PIPELINE STAGE #4 :: Apply Instruction
|
//
|
//
|
//
|
//
|
`ifdef OPT_NEW_INSTRUCTION_SET
|
`ifdef OPT_NEW_INSTRUCTION_SET
|
cpuops #(IMPLEMENT_MPY) doalu(i_clk, i_rst, alu_ce,
|
cpuops #(IMPLEMENT_MPY) doalu(i_clk, i_rst, alu_ce,
|
(opvalid_alu), opn, opA, opB,
|
(opvalid_alu), opn, opA, opB,
|
alu_result, alu_flags, alu_valid, alu_illegal_op,
|
alu_result, alu_flags, alu_valid, alu_illegal_op,
|
alu_busy);
|
alu_busy);
|
`else
|
`else
|
cpuops_deprecated #(IMPLEMENT_MPY) doalu(i_clk, i_rst, alu_ce,
|
cpuops_deprecated #(IMPLEMENT_MPY) doalu(i_clk, i_rst, alu_ce,
|
(opvalid_alu), opn, opA, opB,
|
(opvalid_alu), opn, opA, opB,
|
alu_result, alu_flags, alu_valid, alu_illegal_op);
|
alu_result, alu_flags, alu_valid, alu_illegal_op);
|
assign alu_busy = 1'b0;
|
assign alu_busy = 1'b0;
|
`endif
|
`endif
|
|
|
generate
|
generate
|
if (IMPLEMENT_DIVIDE != 0)
|
if (IMPLEMENT_DIVIDE != 0)
|
begin
|
begin
|
div thedivide(i_clk, (i_rst)||(clear_pipeline), div_ce, opn[0],
|
div thedivide(i_clk, (i_rst)||(clear_pipeline), div_ce, opn[0],
|
opA, opB, div_busy, div_valid, div_error, div_result,
|
opA, opB, div_busy, div_valid, div_error, div_result,
|
div_flags);
|
div_flags);
|
end else begin
|
end else begin
|
assign div_error = 1'b1;
|
assign div_error = 1'b1;
|
assign div_busy = 1'b0;
|
assign div_busy = 1'b0;
|
assign div_valid = 1'b0;
|
assign div_valid = 1'b0;
|
assign div_result= 32'h00;
|
assign div_result= 32'h00;
|
assign div_flags = 4'h0;
|
assign div_flags = 4'h0;
|
end endgenerate
|
end endgenerate
|
|
|
generate
|
generate
|
if (IMPLEMENT_FPU != 0)
|
if (IMPLEMENT_FPU != 0)
|
begin
|
begin
|
//
|
//
|
// sfpu thefpu(i_clk, i_rst, fpu_ce,
|
// sfpu thefpu(i_clk, i_rst, fpu_ce,
|
// opA, opB, fpu_busy, fpu_valid, fpu_err, fpu_result,
|
// opA, opB, fpu_busy, fpu_valid, fpu_err, fpu_result,
|
// fpu_flags);
|
// fpu_flags);
|
//
|
//
|
assign fpu_error = 1'b1;
|
assign fpu_error = 1'b1;
|
assign fpu_busy = 1'b0;
|
assign fpu_busy = 1'b0;
|
assign fpu_valid = 1'b0;
|
assign fpu_valid = 1'b0;
|
assign fpu_result= 32'h00;
|
assign fpu_result= 32'h00;
|
assign fpu_flags = 4'h0;
|
assign fpu_flags = 4'h0;
|
end else begin
|
end else begin
|
assign fpu_error = 1'b1;
|
assign fpu_error = 1'b1;
|
assign fpu_busy = 1'b0;
|
assign fpu_busy = 1'b0;
|
assign fpu_valid = 1'b0;
|
assign fpu_valid = 1'b0;
|
assign fpu_result= 32'h00;
|
assign fpu_result= 32'h00;
|
assign fpu_flags = 4'h0;
|
assign fpu_flags = 4'h0;
|
end endgenerate
|
end endgenerate
|
|
|
|
|
assign set_cond = ((opF[7:4]&opFl[3:0])==opF[3:0]);
|
assign set_cond = ((opF[7:4]&opFl[3:0])==opF[3:0]);
|
initial alF_wr = 1'b0;
|
initial alF_wr = 1'b0;
|
initial alu_wr = 1'b0;
|
initial alu_wr = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
begin
|
begin
|
alu_wr <= 1'b0;
|
alu_wr <= 1'b0;
|
alF_wr <= 1'b0;
|
alF_wr <= 1'b0;
|
end else if (alu_ce)
|
end else if (alu_ce)
|
begin
|
begin
|
// alu_reg <= opR;
|
// alu_reg <= opR;
|
alu_wr <= (opR_wr)&&(set_cond);
|
alu_wr <= (opR_wr)&&(set_cond);
|
alF_wr <= (opF_wr)&&(set_cond);
|
alF_wr <= (opF_wr)&&(set_cond);
|
end else if (~alu_busy) begin
|
end else if (~alu_busy) begin
|
// These are strobe signals, so clear them if not
|
// These are strobe signals, so clear them if not
|
// set for any particular clock
|
// set for any particular clock
|
alu_wr <= (i_halt)&&(i_dbg_we);
|
alu_wr <= (i_halt)&&(i_dbg_we);
|
alF_wr <= 1'b0;
|
alF_wr <= 1'b0;
|
end
|
end
|
|
|
`ifdef OPT_VLIW
|
`ifdef OPT_VLIW
|
reg r_alu_phase;
|
reg r_alu_phase;
|
initial r_alu_phase = 1'b0;
|
initial r_alu_phase = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_alu_phase <= 1'b0;
|
r_alu_phase <= 1'b0;
|
else if ((alu_ce)||(mem_ce)||(div_ce)||(fpu_ce))
|
else if ((alu_ce)||(mem_ce)||(div_ce)||(fpu_ce))
|
r_alu_phase <= op_phase;
|
r_alu_phase <= op_phase;
|
assign alu_phase = r_alu_phase;
|
assign alu_phase = r_alu_phase;
|
`else
|
`else
|
assign alu_phase = 1'b0;
|
assign alu_phase = 1'b0;
|
`endif
|
`endif
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((alu_ce)||(div_ce)||(fpu_ce))
|
if ((alu_ce)||(div_ce)||(fpu_ce))
|
alu_reg <= opR;
|
alu_reg <= opR;
|
else if ((i_halt)&&(i_dbg_we))
|
else if ((i_halt)&&(i_dbg_we))
|
alu_reg <= i_dbg_reg;
|
alu_reg <= i_dbg_reg;
|
|
|
//
|
//
|
// DEBUG Register write access starts here
|
// DEBUG Register write access starts here
|
//
|
//
|
reg dbgv;
|
reg dbgv;
|
initial dbgv = 1'b0;
|
initial dbgv = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
dbgv <= (~i_rst)&&(~alu_ce)&&((i_halt)&&(i_dbg_we));
|
dbgv <= (~i_rst)&&(~alu_ce)&&((i_halt)&&(i_dbg_we));
|
reg [31:0] dbg_val;
|
reg [31:0] dbg_val;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
dbg_val <= i_dbg_data;
|
dbg_val <= i_dbg_data;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((alu_ce)||(mem_ce))
|
if ((alu_ce)||(mem_ce))
|
alu_gie <= op_gie;
|
alu_gie <= op_gie;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((alu_ce)||((master_ce)&&(opvalid_mem)&&(~clear_pipeline)
|
if ((alu_ce)||((master_ce)&&(opvalid_mem)&&(~clear_pipeline)
|
&&(~mem_stalled)))
|
&&(~mem_stalled)))
|
alu_pc <= op_pc;
|
alu_pc <= op_pc;
|
|
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
reg r_alu_illegal;
|
reg r_alu_illegal;
|
initial r_alu_illegal = 0;
|
initial r_alu_illegal = 0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (clear_pipeline)
|
if (clear_pipeline)
|
r_alu_illegal <= 1'b0;
|
r_alu_illegal <= 1'b0;
|
else if ((alu_ce)||(mem_ce))
|
else if ((alu_ce)||(mem_ce))
|
r_alu_illegal <= op_illegal;
|
r_alu_illegal <= op_illegal;
|
assign alu_illegal = (alu_illegal_op)||(r_alu_illegal);
|
assign alu_illegal = (alu_illegal_op)||(r_alu_illegal);
|
`endif
|
`endif
|
|
|
initial alu_pc_valid = 1'b0;
|
initial alu_pc_valid = 1'b0;
|
initial mem_pc_valid = 1'b0;
|
initial mem_pc_valid = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
alu_pc_valid <= 1'b0;
|
alu_pc_valid <= 1'b0;
|
else
|
else
|
alu_pc_valid <= (alu_ce);
|
alu_pc_valid <= (alu_ce);
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
mem_pc_valid <= 1'b0;
|
mem_pc_valid <= 1'b0;
|
else
|
else
|
mem_pc_valid <= (mem_ce);
|
mem_pc_valid <= (mem_ce);
|
|
|
wire bus_lock;
|
wire bus_lock;
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
generate
|
generate
|
if (IMPLEMENT_LOCK != 0)
|
if (IMPLEMENT_LOCK != 0)
|
begin
|
begin
|
reg r_bus_lock;
|
reg [1:0] r_bus_lock;
|
initial r_bus_lock = 1'b0;
|
initial r_bus_lock = 2'b00;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_bus_lock <= 1'b0;
|
r_bus_lock <= 2'b00;
|
else if ((op_ce)&&(op_lock))
|
else if ((op_ce)&&(op_lock))
|
r_bus_lock <= 1'b1;
|
r_bus_lock <= 2'b11;
|
else if (~opvalid_mem)
|
else if ((|r_bus_lock)&&((~opvalid_mem)||(~op_ce)))
|
r_bus_lock <= 1'b0;
|
r_bus_lock <= r_bus_lock + 2'b11;
|
assign bus_lock = r_bus_lock;
|
assign bus_lock = |r_bus_lock;
|
end else begin
|
end else begin
|
assign bus_lock = 1'b0;
|
assign bus_lock = 1'b0;
|
end endgenerate
|
end endgenerate
|
`else
|
`else
|
assign bus_lock = 1'b0;
|
assign bus_lock = 1'b0;
|
`endif
|
`endif
|
|
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
`ifdef OPT_PIPELINED_BUS_ACCESS
|
pipemem #(AW,IMPLEMENT_LOCK) domem(i_clk, i_rst,(mem_ce)&&(set_cond), bus_lock,
|
pipemem #(AW,IMPLEMENT_LOCK) domem(i_clk, i_rst,(mem_ce)&&(set_cond), bus_lock,
|
(opn[0]), opB, opA, opR,
|
(opn[0]), opB, opA, opR,
|
mem_busy, mem_pipe_stalled,
|
mem_busy, mem_pipe_stalled,
|
mem_valid, bus_err, mem_wreg, mem_result,
|
mem_valid, bus_err, mem_wreg, mem_result,
|
mem_cyc_gbl, mem_cyc_lcl,
|
mem_cyc_gbl, mem_cyc_lcl,
|
mem_stb_gbl, mem_stb_lcl,
|
mem_stb_gbl, mem_stb_lcl,
|
mem_we, mem_addr, mem_data,
|
mem_we, mem_addr, mem_data,
|
mem_ack, mem_stall, mem_err, i_wb_data);
|
mem_ack, mem_stall, mem_err, i_wb_data);
|
|
|
`else // PIPELINED_BUS_ACCESS
|
`else // PIPELINED_BUS_ACCESS
|
memops #(AW,IMPLEMENT_LOCK) domem(i_clk, i_rst,(mem_ce)&&(set_cond), bus_lock,
|
memops #(AW,IMPLEMENT_LOCK) domem(i_clk, i_rst,(mem_ce)&&(set_cond), bus_lock,
|
(opn[0]), opB, opA, opR,
|
(opn[0]), opB, opA, opR,
|
mem_busy,
|
mem_busy,
|
mem_valid, bus_err, mem_wreg, mem_result,
|
mem_valid, bus_err, mem_wreg, mem_result,
|
mem_cyc_gbl, mem_cyc_lcl,
|
mem_cyc_gbl, mem_cyc_lcl,
|
mem_stb_gbl, mem_stb_lcl,
|
mem_stb_gbl, mem_stb_lcl,
|
mem_we, mem_addr, mem_data,
|
mem_we, mem_addr, mem_data,
|
mem_ack, mem_stall, mem_err, i_wb_data);
|
mem_ack, mem_stall, mem_err, i_wb_data);
|
`endif // PIPELINED_BUS_ACCESS
|
`endif // PIPELINED_BUS_ACCESS
|
assign mem_rdbusy = ((mem_busy)&&(~mem_we));
|
assign mem_rdbusy = ((mem_busy)&&(~mem_we));
|
|
|
// Either the prefetch or the instruction gets the memory bus, but
|
// Either the prefetch or the instruction gets the memory bus, but
|
// never both.
|
// never both.
|
wbdblpriarb #(32,AW) pformem(i_clk, i_rst,
|
wbdblpriarb #(32,AW) pformem(i_clk, i_rst,
|
// Memory access to the arbiter, priority position
|
// Memory access to the arbiter, priority position
|
mem_cyc_gbl, mem_cyc_lcl, mem_stb_gbl, mem_stb_lcl,
|
mem_cyc_gbl, mem_cyc_lcl, mem_stb_gbl, mem_stb_lcl,
|
mem_we, mem_addr, mem_data, mem_ack, mem_stall, mem_err,
|
mem_we, mem_addr, mem_data, mem_ack, mem_stall, mem_err,
|
// Prefetch access to the arbiter
|
// Prefetch access to the arbiter
|
pf_cyc, 1'b0, pf_stb, 1'b0, pf_we, pf_addr, pf_data,
|
pf_cyc, 1'b0, pf_stb, 1'b0, pf_we, pf_addr, pf_data,
|
pf_ack, pf_stall, pf_err,
|
pf_ack, pf_stall, pf_err,
|
// Common wires, in and out, of the arbiter
|
// Common wires, in and out, of the arbiter
|
o_wb_gbl_cyc, o_wb_lcl_cyc, o_wb_gbl_stb, o_wb_lcl_stb,
|
o_wb_gbl_cyc, o_wb_lcl_cyc, o_wb_gbl_stb, o_wb_lcl_stb,
|
o_wb_we, o_wb_addr, o_wb_data,
|
o_wb_we, o_wb_addr, o_wb_data,
|
i_wb_ack, i_wb_stall, i_wb_err);
|
i_wb_ack, i_wb_stall, i_wb_err);
|
|
|
|
|
|
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
//
|
// PIPELINE STAGE #5 :: Write-back results
|
// PIPELINE STAGE #5 :: Write-back results
|
//
|
//
|
//
|
//
|
// This stage is not allowed to stall. If results are ready to be
|
// This stage is not allowed to stall. If results are ready to be
|
// written back, they are written back at all cost. Sleepy CPU's
|
// written back, they are written back at all cost. Sleepy CPU's
|
// won't prevent write back, nor debug modes, halting the CPU, nor
|
// won't prevent write back, nor debug modes, halting the CPU, nor
|
// anything else. Indeed, the (master_ce) bit is only as relevant
|
// anything else. Indeed, the (master_ce) bit is only as relevant
|
// as knowinig something is available for writeback.
|
// as knowinig something is available for writeback.
|
|
|
//
|
//
|
// Write back to our generic register set ...
|
// Write back to our generic register set ...
|
// When shall we write back? On one of two conditions
|
// When shall we write back? On one of two conditions
|
// Note that the flags needed to be checked before issuing the
|
// Note that the flags needed to be checked before issuing the
|
// bus instruction, so they don't need to be checked here.
|
// bus instruction, so they don't need to be checked here.
|
// Further, alu_wr includes (set_cond), so we don't need to
|
// Further, alu_wr includes (set_cond), so we don't need to
|
// check for that here either.
|
// check for that here either.
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
assign wr_reg_ce = (dbgv)||(~alu_illegal)&&
|
assign wr_reg_ce = (dbgv)||(~alu_illegal)&&
|
(((alu_wr)&&(~clear_pipeline)
|
(((alu_wr)&&(~clear_pipeline)
|
&&((alu_valid)||(div_valid)||(fpu_valid)))
|
&&((alu_valid)||(div_valid)||(fpu_valid)))
|
||(mem_valid));
|
||(mem_valid));
|
`else
|
`else
|
assign wr_reg_ce = (dbgv)||((alu_wr)&&(~clear_pipeline))||(mem_valid)||(div_valid)||(fpu_valid);
|
assign wr_reg_ce = (dbgv)||((alu_wr)&&(~clear_pipeline))||(mem_valid)||(div_valid)||(fpu_valid);
|
`endif
|
`endif
|
// Which register shall be written?
|
// Which register shall be written?
|
// COULD SIMPLIFY THIS: by adding three bits to these registers,
|
// COULD SIMPLIFY THIS: by adding three bits to these registers,
|
// One or PC, one for CC, and one for GIE match
|
// One or PC, one for CC, and one for GIE match
|
// Note that the alu_reg is the register to write on a divide or
|
// Note that the alu_reg is the register to write on a divide or
|
// FPU operation.
|
// FPU operation.
|
assign wr_reg_id = (alu_wr)?alu_reg:mem_wreg;
|
assign wr_reg_id = (alu_wr)?alu_reg:mem_wreg;
|
// Are we writing to the CC register?
|
// Are we writing to the CC register?
|
assign wr_write_cc = (wr_reg_id[3:0] == `CPU_CC_REG);
|
assign wr_write_cc = (wr_reg_id[3:0] == `CPU_CC_REG);
|
// Are we writing to the PC?
|
// Are we writing to the PC?
|
assign wr_write_pc = (wr_reg_id[3:0] == `CPU_PC_REG);
|
assign wr_write_pc = (wr_reg_id[3:0] == `CPU_PC_REG);
|
// What value to write?
|
// What value to write?
|
assign wr_reg_vl = ((mem_valid) ? mem_result
|
assign wr_reg_vl = ((mem_valid) ? mem_result
|
:((div_valid|fpu_valid))
|
:((div_valid|fpu_valid))
|
? ((div_valid) ? div_result:fpu_result)
|
? ((div_valid) ? div_result:fpu_result)
|
:((dbgv) ? dbg_val : alu_result));
|
:((dbgv) ? dbg_val : alu_result));
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (wr_reg_ce)
|
if (wr_reg_ce)
|
regset[wr_reg_id] <= wr_reg_vl;
|
regset[wr_reg_id] <= wr_reg_vl;
|
|
|
//
|
//
|
// Write back to the condition codes/flags register ...
|
// Write back to the condition codes/flags register ...
|
// When shall we write to our flags register? alF_wr already
|
// When shall we write to our flags register? alF_wr already
|
// includes the set condition ...
|
// includes the set condition ...
|
assign wr_flags_ce = ((alF_wr)||(div_valid)||(fpu_valid))&&(~clear_pipeline)&&(~alu_illegal);
|
assign wr_flags_ce = ((alF_wr)||(div_valid)||(fpu_valid))&&(~clear_pipeline)&&(~alu_illegal);
|
assign w_uflags = { uhalt_phase, ufpu_err_flag,
|
assign w_uflags = { uhalt_phase, ufpu_err_flag,
|
udiv_err_flag, ubus_err_flag, trap, ill_err_u,
|
udiv_err_flag, ubus_err_flag, trap, ill_err_u,
|
1'b0, step, 1'b1, sleep,
|
1'b0, step, 1'b1, sleep,
|
((wr_flags_ce)&&(alu_gie))?alu_flags:flags };
|
((wr_flags_ce)&&(alu_gie))?alu_flags:flags };
|
assign w_iflags = { ihalt_phase, ifpu_err_flag,
|
assign w_iflags = { ihalt_phase, ifpu_err_flag,
|
idiv_err_flag, ibus_err_flag, trap, ill_err_i,
|
idiv_err_flag, ibus_err_flag, trap, ill_err_i,
|
break_en, 1'b0, 1'b0, sleep,
|
break_en, 1'b0, 1'b0, sleep,
|
((wr_flags_ce)&&(~alu_gie))?alu_flags:iflags };
|
((wr_flags_ce)&&(~alu_gie))?alu_flags:iflags };
|
|
|
|
|
// What value to write?
|
// What value to write?
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
// If explicitly writing the register itself
|
// If explicitly writing the register itself
|
if ((wr_reg_ce)&&(wr_reg_id[4])&&(wr_write_cc))
|
if ((wr_reg_ce)&&(wr_reg_id[4])&&(wr_write_cc))
|
flags <= wr_reg_vl[3:0];
|
flags <= wr_reg_vl[3:0];
|
// Otherwise if we're setting the flags from an ALU operation
|
// Otherwise if we're setting the flags from an ALU operation
|
else if ((wr_flags_ce)&&(alu_gie))
|
else if ((wr_flags_ce)&&(alu_gie))
|
flags <= (div_valid)?div_flags:((fpu_valid)?fpu_flags
|
flags <= (div_valid)?div_flags:((fpu_valid)?fpu_flags
|
: alu_flags);
|
: alu_flags);
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_cc))
|
if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_cc))
|
iflags <= wr_reg_vl[3:0];
|
iflags <= wr_reg_vl[3:0];
|
else if ((wr_flags_ce)&&(~alu_gie))
|
else if ((wr_flags_ce)&&(~alu_gie))
|
iflags <= (div_valid)?div_flags:((fpu_valid)?fpu_flags
|
iflags <= (div_valid)?div_flags:((fpu_valid)?fpu_flags
|
: alu_flags);
|
: alu_flags);
|
|
|
// The 'break' enable bit. This bit can only be set from supervisor
|
// The 'break' enable bit. This bit can only be set from supervisor
|
// mode. It control what the CPU does upon encountering a break
|
// mode. It control what the CPU does upon encountering a break
|
// instruction.
|
// instruction.
|
//
|
//
|
// The goal, upon encountering a break is that the CPU should stop and
|
// The goal, upon encountering a break is that the CPU should stop and
|
// not execute the break instruction, choosing instead to enter into
|
// not execute the break instruction, choosing instead to enter into
|
// either interrupt mode or halt first.
|
// either interrupt mode or halt first.
|
// if ((break_en) AND (break_instruction)) // user mode or not
|
// if ((break_en) AND (break_instruction)) // user mode or not
|
// HALT CPU
|
// HALT CPU
|
// else if (break_instruction) // only in user mode
|
// else if (break_instruction) // only in user mode
|
// set an interrupt flag, go to supervisor mode
|
// set an interrupt flag, go to supervisor mode
|
// allow supervisor to step the CPU.
|
// allow supervisor to step the CPU.
|
// Upon a CPU halt, any break condition will be reset. The
|
// Upon a CPU halt, any break condition will be reset. The
|
// external debugger will then need to deal with whatever
|
// external debugger will then need to deal with whatever
|
// condition has taken place.
|
// condition has taken place.
|
initial break_en = 1'b0;
|
initial break_en = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(i_halt))
|
if ((i_rst)||(i_halt))
|
break_en <= 1'b0;
|
break_en <= 1'b0;
|
else if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_cc))
|
else if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_cc))
|
break_en <= wr_reg_vl[`CPU_BREAK_BIT];
|
break_en <= wr_reg_vl[`CPU_BREAK_BIT];
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
assign o_break = ((break_en)||(~op_gie))&&(op_break)
|
assign o_break = ((break_en)||(~op_gie))&&(op_break)
|
&&(~alu_valid)&&(~mem_valid)&&(~mem_busy)
|
&&(~alu_valid)&&(~mem_valid)&&(~mem_busy)
|
&&(~div_busy)&&(~fpu_busy)
|
&&(~div_busy)&&(~fpu_busy)
|
&&(~clear_pipeline)
|
&&(~clear_pipeline)
|
||((~alu_gie)&&(bus_err))
|
||((~alu_gie)&&(bus_err))
|
||((~alu_gie)&&(div_valid)&&(div_error))
|
||((~alu_gie)&&(div_valid)&&(div_error))
|
||((~alu_gie)&&(fpu_valid)&&(fpu_error))
|
||((~alu_gie)&&(fpu_valid)&&(fpu_error))
|
||((~alu_gie)&&(alu_pc_valid)&&(alu_illegal));
|
||((~alu_gie)&&(alu_pc_valid)&&(alu_illegal));
|
`else
|
`else
|
assign o_break = (((break_en)||(~op_gie))&&(op_break)
|
assign o_break = (((break_en)||(~op_gie))&&(op_break)
|
&&(~alu_valid)&&(~mem_valid)&&(~mem_busy)
|
&&(~alu_valid)&&(~mem_valid)&&(~mem_busy)
|
&&(~clear_pipeline))
|
&&(~clear_pipeline))
|
||((~alu_gie)&&(bus_err))
|
||((~alu_gie)&&(bus_err))
|
||((~alu_gie)&&(div_valid)&&(div_error))
|
||((~alu_gie)&&(div_valid)&&(div_error))
|
||((~alu_gie)&&(fpu_valid)&&(fpu_error));
|
||((~alu_gie)&&(fpu_valid)&&(fpu_error));
|
`endif
|
`endif
|
|
|
|
|
// The sleep register. Setting the sleep register causes the CPU to
|
// The sleep register. Setting the sleep register causes the CPU to
|
// sleep until the next interrupt. Setting the sleep register within
|
// sleep until the next interrupt. Setting the sleep register within
|
// interrupt mode causes the processor to halt until a reset. This is
|
// interrupt mode causes the processor to halt until a reset. This is
|
// a panic/fault halt. The trick is that you cannot be allowed to
|
// a panic/fault halt. The trick is that you cannot be allowed to
|
// set the sleep bit and switch to supervisor mode in the same
|
// set the sleep bit and switch to supervisor mode in the same
|
// instruction: users are not allowed to halt the CPU.
|
// instruction: users are not allowed to halt the CPU.
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(w_switch_to_interrupt))
|
if ((i_rst)||(w_switch_to_interrupt))
|
sleep <= 1'b0;
|
sleep <= 1'b0;
|
else if ((wr_reg_ce)&&(wr_write_cc)&&(~alu_gie))
|
else if ((wr_reg_ce)&&(wr_write_cc)&&(~alu_gie))
|
// In supervisor mode, we have no protections. The
|
// In supervisor mode, we have no protections. The
|
// supervisor can set the sleep bit however he wants.
|
// supervisor can set the sleep bit however he wants.
|
// Well ... not quite. Switching to user mode and
|
// Well ... not quite. Switching to user mode and
|
// sleep mode shouold only be possible if the interrupt
|
// sleep mode shouold only be possible if the interrupt
|
// flag isn't set.
|
// flag isn't set.
|
// Thus: if (i_interrupt)&&(wr_reg_vl[GIE])
|
// Thus: if (i_interrupt)&&(wr_reg_vl[GIE])
|
// don't set the sleep bit
|
// don't set the sleep bit
|
// otherwise however it would o.w. be set
|
// otherwise however it would o.w. be set
|
sleep <= (wr_reg_vl[`CPU_SLEEP_BIT])
|
sleep <= (wr_reg_vl[`CPU_SLEEP_BIT])
|
&&((~i_interrupt)||(~wr_reg_vl[`CPU_GIE_BIT]));
|
&&((~i_interrupt)||(~wr_reg_vl[`CPU_GIE_BIT]));
|
else if ((wr_reg_ce)&&(wr_write_cc)&&(wr_reg_vl[`CPU_GIE_BIT]))
|
else if ((wr_reg_ce)&&(wr_write_cc)&&(wr_reg_vl[`CPU_GIE_BIT]))
|
// In user mode, however, you can only set the sleep
|
// In user mode, however, you can only set the sleep
|
// mode while remaining in user mode. You can't switch
|
// mode while remaining in user mode. You can't switch
|
// to sleep mode *and* supervisor mode at the same
|
// to sleep mode *and* supervisor mode at the same
|
// time, lest you halt the CPU.
|
// time, lest you halt the CPU.
|
sleep <= wr_reg_vl[`CPU_SLEEP_BIT];
|
sleep <= wr_reg_vl[`CPU_SLEEP_BIT];
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(w_switch_to_interrupt))
|
if ((i_rst)||(w_switch_to_interrupt))
|
step <= 1'b0;
|
step <= 1'b0;
|
else if ((wr_reg_ce)&&(~alu_gie)&&(wr_reg_id[4])&&(wr_write_cc))
|
else if ((wr_reg_ce)&&(~alu_gie)&&(wr_reg_id[4])&&(wr_write_cc))
|
step <= wr_reg_vl[`CPU_STEP_BIT];
|
step <= wr_reg_vl[`CPU_STEP_BIT];
|
else if (((alu_pc_valid)||(mem_pc_valid))&&(step)&&(gie))
|
else if (((alu_pc_valid)||(mem_pc_valid))&&(step)&&(gie))
|
step <= 1'b0;
|
step <= 1'b0;
|
|
|
// The GIE register. Only interrupts can disable the interrupt register
|
// The GIE register. Only interrupts can disable the interrupt register
|
assign w_switch_to_interrupt = (gie)&&(
|
assign w_switch_to_interrupt = (gie)&&(
|
// On interrupt (obviously)
|
// On interrupt (obviously)
|
((i_interrupt)&&(~alu_phase)&&(~bus_lock))
|
((i_interrupt)&&(~alu_phase)&&(~bus_lock))
|
// If we are stepping the CPU
|
// If we are stepping the CPU
|
||(((alu_pc_valid)||(mem_pc_valid))&&(step)&&(~alu_phase)&&(~bus_lock))
|
||(((alu_pc_valid)||(mem_pc_valid))&&(step)&&(~alu_phase)&&(~bus_lock))
|
// If we encounter a break instruction, if the break
|
// If we encounter a break instruction, if the break
|
// enable isn't set.
|
// enable isn't set.
|
||((master_ce)&&(~mem_rdbusy)&&(~div_busy)&&(~fpu_busy)
|
||((master_ce)&&(~mem_rdbusy)&&(~div_busy)&&(~fpu_busy)
|
&&(op_break)&&(~break_en))
|
&&(op_break)&&(~break_en))
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
// On an illegal instruction
|
// On an illegal instruction
|
||((alu_pc_valid)&&(alu_illegal))
|
||((alu_pc_valid)&&(alu_illegal))
|
`endif
|
`endif
|
// On division by zero. If the divide isn't
|
// On division by zero. If the divide isn't
|
// implemented, div_valid and div_error will be short
|
// implemented, div_valid and div_error will be short
|
// circuited and that logic will be bypassed
|
// circuited and that logic will be bypassed
|
||((div_valid)&&(div_error))
|
||((div_valid)&&(div_error))
|
// Same thing on a floating point error.
|
// Same thing on a floating point error.
|
||((fpu_valid)&&(fpu_error))
|
||((fpu_valid)&&(fpu_error))
|
//
|
//
|
||(bus_err)
|
||(bus_err)
|
// If we write to the CC register
|
// If we write to the CC register
|
||((wr_reg_ce)&&(~wr_reg_vl[`CPU_GIE_BIT])
|
||((wr_reg_ce)&&(~wr_reg_vl[`CPU_GIE_BIT])
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
);
|
);
|
assign w_release_from_interrupt = (~gie)&&(~i_interrupt)
|
assign w_release_from_interrupt = (~gie)&&(~i_interrupt)
|
// Then if we write the CC register
|
// Then if we write the CC register
|
&&(((wr_reg_ce)&&(wr_reg_vl[`CPU_GIE_BIT])
|
&&(((wr_reg_ce)&&(wr_reg_vl[`CPU_GIE_BIT])
|
&&(~wr_reg_id[4])&&(wr_write_cc))
|
&&(~wr_reg_id[4])&&(wr_write_cc))
|
);
|
);
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
gie <= 1'b0;
|
gie <= 1'b0;
|
else if (w_switch_to_interrupt)
|
else if (w_switch_to_interrupt)
|
gie <= 1'b0;
|
gie <= 1'b0;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
gie <= 1'b1;
|
gie <= 1'b1;
|
|
|
initial trap = 1'b0;
|
initial trap = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
trap <= 1'b0;
|
trap <= 1'b0;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
trap <= 1'b0;
|
trap <= 1'b0;
|
else if ((alu_gie)&&(wr_reg_ce)&&(~wr_reg_vl[`CPU_GIE_BIT])
|
else if ((alu_gie)&&(wr_reg_ce)&&(~wr_reg_vl[`CPU_GIE_BIT])
|
&&(wr_write_cc)) // &&(wr_reg_id[4]) implied
|
&&(wr_write_cc)) // &&(wr_reg_id[4]) implied
|
trap <= 1'b1;
|
trap <= 1'b1;
|
else if ((wr_reg_ce)&&(wr_write_cc)&&(wr_reg_id[4]))
|
else if ((wr_reg_ce)&&(wr_write_cc)&&(wr_reg_id[4]))
|
trap <= wr_reg_vl[`CPU_TRAP_BIT];
|
trap <= wr_reg_vl[`CPU_TRAP_BIT];
|
|
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
`ifdef OPT_ILLEGAL_INSTRUCTION
|
initial ill_err_i = 1'b0;
|
initial ill_err_i = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
ill_err_i <= 1'b0;
|
ill_err_i <= 1'b0;
|
// The debug interface can clear this bit
|
// Only the debug interface can clear this bit
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
&&(~wr_reg_vl[`CPU_ILL_BIT]))
|
&&(~wr_reg_vl[`CPU_ILL_BIT]))
|
ill_err_i <= 1'b0;
|
ill_err_i <= 1'b0;
|
else if ((alu_pc_valid)&&(alu_illegal)&&(~alu_gie))
|
else if ((alu_pc_valid)&&(alu_illegal)&&(~alu_gie))
|
ill_err_i <= 1'b1;
|
ill_err_i <= 1'b1;
|
initial ill_err_u = 1'b0;
|
initial ill_err_u = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
ill_err_u <= 1'b0;
|
ill_err_u <= 1'b0;
|
// The bit is automatically cleared on release from interrupt
|
// The bit is automatically cleared on release from interrupt
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
ill_err_u <= 1'b0;
|
ill_err_u <= 1'b0;
|
// If the supervisor writes to this register, clearing the
|
// If the supervisor writes to this register, clearing the
|
// bit, then clear it
|
// bit, then clear it
|
else if (((~alu_gie)||(dbgv))
|
else if (((~alu_gie)||(dbgv))
|
&&(wr_reg_ce)&&(~wr_reg_vl[`CPU_ILL_BIT])
|
&&(wr_reg_ce)&&(~wr_reg_vl[`CPU_ILL_BIT])
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
ill_err_u <= 1'b0;
|
ill_err_u <= 1'b0;
|
else if ((alu_pc_valid)&&(alu_illegal)&&(alu_gie))
|
else if ((alu_pc_valid)&&(alu_illegal)&&(alu_gie))
|
ill_err_u <= 1'b1;
|
ill_err_u <= 1'b1;
|
`else
|
`else
|
assign ill_err_u = 1'b0;
|
assign ill_err_u = 1'b0;
|
assign ill_err_i = 1'b0;
|
assign ill_err_i = 1'b0;
|
`endif
|
`endif
|
// Supervisor/interrupt bus error flag -- this will crash the CPU if
|
// Supervisor/interrupt bus error flag -- this will crash the CPU if
|
// ever set.
|
// ever set.
|
initial ibus_err_flag = 1'b0;
|
initial ibus_err_flag = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
ibus_err_flag <= 1'b0;
|
ibus_err_flag <= 1'b0;
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
&&(~wr_reg_vl[`CPU_BUSERR_BIT]))
|
&&(~wr_reg_vl[`CPU_BUSERR_BIT]))
|
ibus_err_flag <= 1'b0;
|
ibus_err_flag <= 1'b0;
|
else if ((bus_err)&&(~alu_gie))
|
else if ((bus_err)&&(~alu_gie))
|
ibus_err_flag <= 1'b1;
|
ibus_err_flag <= 1'b1;
|
// User bus error flag -- if ever set, it will cause an interrupt to
|
// User bus error flag -- if ever set, it will cause an interrupt to
|
// supervisor mode.
|
// supervisor mode.
|
initial ubus_err_flag = 1'b0;
|
initial ubus_err_flag = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
ubus_err_flag <= 1'b0;
|
ubus_err_flag <= 1'b0;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
ubus_err_flag <= 1'b0;
|
ubus_err_flag <= 1'b0;
|
else if (((~alu_gie)||(dbgv))&&(wr_reg_ce)
|
else if (((~alu_gie)||(dbgv))&&(wr_reg_ce)
|
&&(~wr_reg_vl[`CPU_BUSERR_BIT])
|
&&(~wr_reg_vl[`CPU_BUSERR_BIT])
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
ubus_err_flag <= 1'b0;
|
ubus_err_flag <= 1'b0;
|
else if ((bus_err)&&(alu_gie))
|
else if ((bus_err)&&(alu_gie))
|
ubus_err_flag <= 1'b1;
|
ubus_err_flag <= 1'b1;
|
|
|
generate
|
generate
|
if (IMPLEMENT_DIVIDE != 0)
|
if (IMPLEMENT_DIVIDE != 0)
|
begin
|
begin
|
reg r_idiv_err_flag, r_udiv_err_flag;
|
reg r_idiv_err_flag, r_udiv_err_flag;
|
|
|
// Supervisor/interrupt divide (by zero) error flag -- this will
|
// Supervisor/interrupt divide (by zero) error flag -- this will
|
// crash the CPU if ever set. This bit is thus available for us
|
// crash the CPU if ever set. This bit is thus available for us
|
// to be able to tell if/why the CPU crashed.
|
// to be able to tell if/why the CPU crashed.
|
initial r_idiv_err_flag = 1'b0;
|
initial r_idiv_err_flag = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_idiv_err_flag <= 1'b0;
|
r_idiv_err_flag <= 1'b0;
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
&&(~wr_reg_vl[`CPU_DIVERR_BIT]))
|
&&(~wr_reg_vl[`CPU_DIVERR_BIT]))
|
r_idiv_err_flag <= 1'b0;
|
r_idiv_err_flag <= 1'b0;
|
else if ((div_error)&&(div_valid)&&(~alu_gie))
|
else if ((div_error)&&(div_valid)&&(~alu_gie))
|
r_idiv_err_flag <= 1'b1;
|
r_idiv_err_flag <= 1'b1;
|
// User divide (by zero) error flag -- if ever set, it will
|
// User divide (by zero) error flag -- if ever set, it will
|
// cause a sudden switch interrupt to supervisor mode.
|
// cause a sudden switch interrupt to supervisor mode.
|
initial r_udiv_err_flag = 1'b0;
|
initial r_udiv_err_flag = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_udiv_err_flag <= 1'b0;
|
r_udiv_err_flag <= 1'b0;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
r_udiv_err_flag <= 1'b0;
|
r_udiv_err_flag <= 1'b0;
|
else if (((~alu_gie)||(dbgv))&&(wr_reg_ce)
|
else if (((~alu_gie)||(dbgv))&&(wr_reg_ce)
|
&&(~wr_reg_vl[`CPU_DIVERR_BIT])
|
&&(~wr_reg_vl[`CPU_DIVERR_BIT])
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
r_udiv_err_flag <= 1'b0;
|
r_udiv_err_flag <= 1'b0;
|
else if ((div_error)&&(alu_gie)&&(div_valid))
|
else if ((div_error)&&(alu_gie)&&(div_valid))
|
r_udiv_err_flag <= 1'b1;
|
r_udiv_err_flag <= 1'b1;
|
|
|
assign idiv_err_flag = r_idiv_err_flag;
|
assign idiv_err_flag = r_idiv_err_flag;
|
assign udiv_err_flag = r_udiv_err_flag;
|
assign udiv_err_flag = r_udiv_err_flag;
|
end else begin
|
end else begin
|
assign idiv_err_flag = 1'b0;
|
assign idiv_err_flag = 1'b0;
|
assign udiv_err_flag = 1'b0;
|
assign udiv_err_flag = 1'b0;
|
end endgenerate
|
end endgenerate
|
|
|
generate
|
generate
|
if (IMPLEMENT_FPU !=0)
|
if (IMPLEMENT_FPU !=0)
|
begin
|
begin
|
// Supervisor/interrupt floating point error flag -- this will
|
// Supervisor/interrupt floating point error flag -- this will
|
// crash the CPU if ever set.
|
// crash the CPU if ever set.
|
reg r_ifpu_err_flag, r_ufpu_err_flag;
|
reg r_ifpu_err_flag, r_ufpu_err_flag;
|
initial r_ifpu_err_flag = 1'b0;
|
initial r_ifpu_err_flag = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_ifpu_err_flag <= 1'b0;
|
r_ifpu_err_flag <= 1'b0;
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
else if ((dbgv)&&(wr_reg_id == {1'b0, `CPU_CC_REG})
|
&&(~wr_reg_vl[`CPU_FPUERR_BIT]))
|
&&(~wr_reg_vl[`CPU_FPUERR_BIT]))
|
r_ifpu_err_flag <= 1'b0;
|
r_ifpu_err_flag <= 1'b0;
|
else if ((fpu_error)&&(fpu_valid)&&(~alu_gie))
|
else if ((fpu_error)&&(fpu_valid)&&(~alu_gie))
|
r_ifpu_err_flag <= 1'b1;
|
r_ifpu_err_flag <= 1'b1;
|
// User floating point error flag -- if ever set, it will cause
|
// User floating point error flag -- if ever set, it will cause
|
// a sudden switch interrupt to supervisor mode.
|
// a sudden switch interrupt to supervisor mode.
|
initial r_ufpu_err_flag = 1'b0;
|
initial r_ufpu_err_flag = 1'b0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
r_ufpu_err_flag <= 1'b0;
|
r_ufpu_err_flag <= 1'b0;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
r_ufpu_err_flag <= 1'b0;
|
r_ufpu_err_flag <= 1'b0;
|
else if (((~alu_gie)||(dbgv))&&(wr_reg_ce)
|
else if (((~alu_gie)||(dbgv))&&(wr_reg_ce)
|
&&(~wr_reg_vl[`CPU_FPUERR_BIT])
|
&&(~wr_reg_vl[`CPU_FPUERR_BIT])
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
&&(wr_reg_id[4])&&(wr_write_cc))
|
r_ufpu_err_flag <= 1'b0;
|
r_ufpu_err_flag <= 1'b0;
|
else if ((fpu_error)&&(alu_gie)&&(fpu_valid))
|
else if ((fpu_error)&&(alu_gie)&&(fpu_valid))
|
r_ufpu_err_flag <= 1'b1;
|
r_ufpu_err_flag <= 1'b1;
|
|
|
assign ifpu_err_flag = r_ifpu_err_flag;
|
assign ifpu_err_flag = r_ifpu_err_flag;
|
assign ufpu_err_flag = r_ufpu_err_flag;
|
assign ufpu_err_flag = r_ufpu_err_flag;
|
end else begin
|
end else begin
|
assign ifpu_err_flag = 1'b0;
|
assign ifpu_err_flag = 1'b0;
|
assign ufpu_err_flag = 1'b0;
|
assign ufpu_err_flag = 1'b0;
|
end endgenerate
|
end endgenerate
|
|
|
`ifdef OPT_VLIW
|
`ifdef OPT_VLIW
|
reg r_ihalt_phase, r_uhalt_phase;
|
reg r_ihalt_phase, r_uhalt_phase;
|
|
|
initial r_ihalt_phase = 0;
|
initial r_ihalt_phase = 0;
|
initial r_uhalt_phase = 0;
|
initial r_uhalt_phase = 0;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (~alu_gie)
|
if (~alu_gie)
|
r_ihalt_phase <= alu_phase;
|
r_ihalt_phase <= alu_phase;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (alu_gie)
|
if (alu_gie)
|
r_uhalt_phase <= alu_phase;
|
r_uhalt_phase <= alu_phase;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
r_uhalt_phase <= 1'b0;
|
r_uhalt_phase <= 1'b0;
|
|
|
assign ihalt_phase = r_ihalt_phase;
|
assign ihalt_phase = r_ihalt_phase;
|
assign uhalt_phase = r_uhalt_phase;
|
assign uhalt_phase = r_uhalt_phase;
|
`else
|
`else
|
assign ihalt_phase = 1'b0;
|
assign ihalt_phase = 1'b0;
|
assign uhalt_phase = 1'b0;
|
assign uhalt_phase = 1'b0;
|
`endif
|
`endif
|
|
|
//
|
//
|
// Write backs to the PC register, and general increments of it
|
// Write backs to the PC register, and general increments of it
|
// We support two: upc and ipc. If the instruction is normal,
|
// We support two: upc and ipc. If the instruction is normal,
|
// we increment upc, if interrupt level we increment ipc. If
|
// we increment upc, if interrupt level we increment ipc. If
|
// the instruction writes the PC, we write whichever PC is appropriate.
|
// the instruction writes the PC, we write whichever PC is appropriate.
|
//
|
//
|
// Do we need to all our partial results from the pipeline?
|
// Do we need to all our partial results from the pipeline?
|
// What happens when the pipeline has gie and ~gie instructions within
|
// What happens when the pipeline has gie and ~gie instructions within
|
// it? Do we clear both? What if a gie instruction tries to clear
|
// it? Do we clear both? What if a gie instruction tries to clear
|
// a non-gie instruction?
|
// a non-gie instruction?
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((wr_reg_ce)&&(wr_reg_id[4])&&(wr_write_pc))
|
if ((wr_reg_ce)&&(wr_reg_id[4])&&(wr_write_pc))
|
upc <= wr_reg_vl[(AW-1):0];
|
upc <= wr_reg_vl[(AW-1):0];
|
else if ((alu_gie)&&
|
else if ((alu_gie)&&
|
(((alu_pc_valid)&&(~clear_pipeline))
|
(((alu_pc_valid)&&(~clear_pipeline))
|
||(mem_pc_valid)))
|
||(mem_pc_valid)))
|
upc <= alu_pc;
|
upc <= alu_pc;
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
ipc <= RESET_ADDRESS;
|
ipc <= RESET_ADDRESS;
|
else if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_pc))
|
else if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_pc))
|
ipc <= wr_reg_vl[(AW-1):0];
|
ipc <= wr_reg_vl[(AW-1):0];
|
else if ((~alu_gie)&&
|
else if ((~alu_gie)&&
|
(((alu_pc_valid)&&(~clear_pipeline))
|
(((alu_pc_valid)&&(~clear_pipeline))
|
||(mem_pc_valid)))
|
||(mem_pc_valid)))
|
ipc <= alu_pc;
|
ipc <= alu_pc;
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if (i_rst)
|
if (i_rst)
|
pf_pc <= RESET_ADDRESS;
|
pf_pc <= RESET_ADDRESS;
|
else if (w_switch_to_interrupt)
|
else if (w_switch_to_interrupt)
|
pf_pc <= ipc;
|
pf_pc <= ipc;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
pf_pc <= upc;
|
pf_pc <= upc;
|
else if ((wr_reg_ce)&&(wr_reg_id[4] == gie)&&(wr_write_pc))
|
else if ((wr_reg_ce)&&(wr_reg_id[4] == gie)&&(wr_write_pc))
|
pf_pc <= wr_reg_vl[(AW-1):0];
|
pf_pc <= wr_reg_vl[(AW-1):0];
|
`ifdef OPT_PIPELINED
|
`ifdef OPT_PIPELINED
|
else if ((dcd_early_branch)&&(~clear_pipeline))
|
else if ((dcd_early_branch)&&(~clear_pipeline))
|
pf_pc <= dcd_branch_pc + 1;
|
pf_pc <= dcd_branch_pc + 1;
|
else if ((new_pc)||((~dcd_stalled)&&(pf_valid)))
|
else if ((new_pc)||((~dcd_stalled)&&(pf_valid)))
|
pf_pc <= pf_pc + {{(AW-1){1'b0}},1'b1};
|
pf_pc <= pf_pc + {{(AW-1){1'b0}},1'b1};
|
`else
|
`else
|
else if ((alu_pc_valid)&&(~clear_pipeline))
|
else if ((alu_pc_valid)&&(~clear_pipeline))
|
pf_pc <= alu_pc;
|
pf_pc <= alu_pc;
|
`endif
|
`endif
|
|
|
initial new_pc = 1'b1;
|
initial new_pc = 1'b1;
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
if ((i_rst)||(i_clear_pf_cache))
|
if ((i_rst)||(i_clear_pf_cache))
|
new_pc <= 1'b1;
|
new_pc <= 1'b1;
|
else if (w_switch_to_interrupt)
|
else if (w_switch_to_interrupt)
|
new_pc <= 1'b1;
|
new_pc <= 1'b1;
|
else if (w_release_from_interrupt)
|
else if (w_release_from_interrupt)
|
new_pc <= 1'b1;
|
new_pc <= 1'b1;
|
else if ((wr_reg_ce)&&(wr_reg_id[4] == gie)&&(wr_write_pc))
|
else if ((wr_reg_ce)&&(wr_reg_id[4] == gie)&&(wr_write_pc))
|
new_pc <= 1'b1;
|
new_pc <= 1'b1;
|
else
|
else
|
new_pc <= 1'b0;
|
new_pc <= 1'b0;
|
|
|
//
|
//
|
// The debug interface
|
// The debug interface
|
generate
|
generate
|
if (AW<32)
|
if (AW<32)
|
begin
|
begin
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
begin
|
begin
|
o_dbg_reg <= regset[i_dbg_reg];
|
o_dbg_reg <= regset[i_dbg_reg];
|
if (i_dbg_reg[3:0] == `CPU_PC_REG)
|
if (i_dbg_reg[3:0] == `CPU_PC_REG)
|
o_dbg_reg <= {{(32-AW){1'b0}},(i_dbg_reg[4])?upc:ipc};
|
o_dbg_reg <= {{(32-AW){1'b0}},(i_dbg_reg[4])?upc:ipc};
|
else if (i_dbg_reg[3:0] == `CPU_CC_REG)
|
else if (i_dbg_reg[3:0] == `CPU_CC_REG)
|
begin
|
begin
|
o_dbg_reg[13:0] <= (i_dbg_reg[4])?w_uflags:w_iflags;
|
o_dbg_reg[13:0] <= (i_dbg_reg[4])?w_uflags:w_iflags;
|
o_dbg_reg[`CPU_GIE_BIT] <= gie;
|
o_dbg_reg[`CPU_GIE_BIT] <= gie;
|
end
|
end
|
end
|
end
|
end else begin
|
end else begin
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
begin
|
begin
|
o_dbg_reg <= regset[i_dbg_reg];
|
o_dbg_reg <= regset[i_dbg_reg];
|
if (i_dbg_reg[3:0] == `CPU_PC_REG)
|
if (i_dbg_reg[3:0] == `CPU_PC_REG)
|
o_dbg_reg <= (i_dbg_reg[4])?upc:ipc;
|
o_dbg_reg <= (i_dbg_reg[4])?upc:ipc;
|
else if (i_dbg_reg[3:0] == `CPU_CC_REG)
|
else if (i_dbg_reg[3:0] == `CPU_CC_REG)
|
begin
|
begin
|
o_dbg_reg[13:0] <= (i_dbg_reg[4])?w_uflags:w_iflags;
|
o_dbg_reg[13:0] <= (i_dbg_reg[4])?w_uflags:w_iflags;
|
o_dbg_reg[`CPU_GIE_BIT] <= gie;
|
o_dbg_reg[`CPU_GIE_BIT] <= gie;
|
end
|
end
|
end
|
end
|
end endgenerate
|
end endgenerate
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
o_dbg_cc <= { o_break, bus_err, gie, sleep };
|
o_dbg_cc <= { o_break, bus_err, gie, sleep };
|
|
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
o_dbg_stall <= (i_halt)&&(
|
o_dbg_stall <= (i_halt)&&(
|
(pf_cyc)||(mem_cyc_gbl)||(mem_cyc_lcl)||(mem_busy)
|
(pf_cyc)||(mem_cyc_gbl)||(mem_cyc_lcl)||(mem_busy)
|
||((~opvalid)&&(~i_rst)&&(~dcd_illegal))
|
||((~opvalid)&&(~i_rst)&&(~dcd_illegal))
|
||((~dcdvalid)&&(~i_rst)&&(~pf_illegal)));
|
||((~dcdvalid)&&(~i_rst)&&(~pf_illegal)));
|
|
|
//
|
//
|
//
|
//
|
// Produce accounting outputs: Account for any CPU stalls, so we can
|
// Produce accounting outputs: Account for any CPU stalls, so we can
|
// later evaluate how well we are doing.
|
// later evaluate how well we are doing.
|
//
|
//
|
//
|
//
|
assign o_op_stall = (master_ce)&&(op_stall);
|
assign o_op_stall = (master_ce)&&(op_stall);
|
assign o_pf_stall = (master_ce)&&(~pf_valid);
|
assign o_pf_stall = (master_ce)&&(~pf_valid);
|
assign o_i_count = (alu_pc_valid)&&(~clear_pipeline);
|
assign o_i_count = (alu_pc_valid)&&(~clear_pipeline);
|
|
|
`ifdef DEBUG_SCOPE
|
`ifdef DEBUG_SCOPE
|
always @(posedge i_clk)
|
always @(posedge i_clk)
|
o_debug <= {
|
o_debug <= {
|
/*
|
o_break, i_wb_err, pf_pc[1:0],
|
i_wb_err, pf_pc[2:0],
|
flags,
|
flags,
|
pf_valid, dcdvalid, opvalid, alu_valid, mem_valid,
|
pf_valid, dcdvalid, opvalid, alu_valid, mem_valid,
|
op_ce, alu_ce, mem_ce,
|
op_ce, alu_ce, mem_ce,
|
//
|
//
|
master_ce, opvalid_alu, opvalid_mem,
|
master_ce, opvalid_alu, opvalid_mem,
|
//
|
//
|
alu_stall, mem_busy, op_pipe, mem_pipe_stalled,
|
alu_stall, mem_busy, op_pipe, mem_pipe_stalled,
|
mem_we,
|
mem_we,
|
// ((opvalid_alu)&&(alu_stall))
|
// ((opvalid_alu)&&(alu_stall))
|
// ||((opvalid_mem)&&(~op_pipe)&&(mem_busy))
|
// ||((opvalid_mem)&&(~op_pipe)&&(mem_busy))
|
// ||((opvalid_mem)&&( op_pipe)&&(mem_pipe_stalled)));
|
// ||((opvalid_mem)&&( op_pipe)&&(mem_pipe_stalled)));
|
// opA[23:20], opA[3:0],
|
// opA[23:20], opA[3:0],
|
gie, sleep, wr_reg_ce, wr_reg_vl[4:0]
|
gie, sleep, wr_reg_ce, wr_reg_vl[4:0]
|
|
*/
|
|
/*
|
/*
|
i_rst, master_ce, (new_pc),
|
i_rst, master_ce, (new_pc),
|
((dcd_early_branch)&&(dcdvalid)),
|
((dcd_early_branch)&&(dcdvalid)),
|
pf_valid, pf_illegal,
|
pf_valid, pf_illegal,
|
op_ce, dcd_ce, dcdvalid, dcd_stalled,
|
op_ce, dcd_ce, dcdvalid, dcd_stalled,
|
pf_cyc, pf_stb, pf_we, pf_ack, pf_stall, pf_err,
|
pf_cyc, pf_stb, pf_we, pf_ack, pf_stall, pf_err,
|
pf_pc[7:0], pf_addr[7:0]
|
pf_pc[7:0], pf_addr[7:0]
|
*/
|
*/
|
/*
|
/*
|
i_wb_err, gie, alu_illegal,
|
i_wb_err, gie, alu_illegal,
|
(new_pc)||((dcd_early_branch)&&(~clear_pipeline)),
|
(new_pc)||((dcd_early_branch)&&(~clear_pipeline)),
|
mem_busy,
|
mem_busy,
|
(mem_busy)?{ (o_wb_gbl_stb|o_wb_lcl_stb), o_wb_we,
|
(mem_busy)?{ (o_wb_gbl_stb|o_wb_lcl_stb), o_wb_we,
|
o_wb_addr[8:0] }
|
o_wb_addr[8:0] }
|
: { instruction[31:21] },
|
: { instruction[31:21] },
|
pf_valid, (pf_valid) ? alu_pc[14:0]
|
pf_valid, (pf_valid) ? alu_pc[14:0]
|
:{ pf_cyc, pf_stb, pf_pc[12:0] }
|
:{ pf_cyc, pf_stb, pf_pc[12:0] }
|
*/
|
*/
|
i_wb_err, gie, new_pc, dcd_early_branch, // 4
|
/*
|
pf_valid, pf_cyc, pf_stb, instruction_pc[0], // 4
|
i_wb_err, gie, new_pc, dcd_early_branch, // 4
|
instruction[30:27], // 4
|
pf_valid, pf_cyc, pf_stb, instruction_pc[0], // 4
|
dcd_gie, mem_busy, o_wb_gbl_cyc, o_wb_gbl_stb, // 4
|
instruction[30:27], // 4
|
dcdvalid,
|
dcd_gie, mem_busy, o_wb_gbl_cyc, o_wb_gbl_stb, // 4
|
((dcd_early_branch)&&(~clear_pipeline)) // 15
|
dcdvalid,
|
? dcd_branch_pc[14:0]:pf_pc[14:0]
|
((dcd_early_branch)&&(~clear_pipeline)) // 15
|
|
? dcd_branch_pc[14:0]:pf_pc[14:0]
|
|
*/
|
};
|
};
|
`endif
|
`endif
|
|
|
endmodule
|
endmodule
|
|
|