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[/] [openrisc/] [trunk/] [or1200/] [rtl/] [verilog/] [or1200_genpc.v] - Rev 588
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////////////////////////////////////////////////////////////////////// //// //// //// OR1200's generate PC //// //// //// //// This file is part of the OpenRISC 1200 project //// //// http://www.opencores.org/project,or1k //// //// //// //// Description //// //// PC, interface to IC. //// //// //// //// To Do: //// //// - make it smaller and faster //// //// //// //// Author(s): //// //// - Damjan Lampret, lampret@opencores.org //// //// //// ////////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2000 Authors and OPENCORES.ORG //// //// //// //// This source file may be used and distributed without //// //// restriction provided that this copyright statement is not //// //// removed from the file and that any derivative work contains //// //// the original copyright notice and the associated disclaimer. //// //// //// //// This source file is free software; you can redistribute it //// //// and/or modify it under the terms of the GNU Lesser General //// //// Public License as published by the Free Software Foundation; //// //// either version 2.1 of the License, or (at your option) any //// //// later version. //// //// //// //// This source is distributed in the hope that it will be //// //// useful, but WITHOUT ANY WARRANTY; without even the implied //// //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //// //// PURPOSE. See the GNU Lesser General Public License for more //// //// details. //// //// //// //// You should have received a copy of the GNU Lesser General //// //// Public License along with this source; if not, download it //// //// from http://www.opencores.org/lgpl.shtml //// //// //// ////////////////////////////////////////////////////////////////////// // // $Log: or1200_genpc.v,v $ // Revision 2.0 2010/06/30 11:00:00 ORSoC // Major update: // Structure reordered and bugs fixed. // synopsys translate_off `include "timescale.v" // synopsys translate_on `include "or1200_defines.v" module or1200_genpc( // Clock and reset clk, rst, // External i/f to IC icpu_adr_o, icpu_cycstb_o, icpu_sel_o, icpu_tag_o, icpu_rty_i, icpu_adr_i, // Internal i/f pre_branch_op, branch_op, except_type, except_prefix, id_branch_addrtarget, ex_branch_addrtarget, muxed_b, operand_b, flag, flagforw, ex_branch_taken, except_start, epcr, spr_dat_i, spr_pc_we, genpc_refetch, genpc_freeze, no_more_dslot ); // // I/O // // // Clock and reset // input clk; input rst; // // External i/f to IC // output [31:0] icpu_adr_o; output icpu_cycstb_o; output [3:0] icpu_sel_o; output [3:0] icpu_tag_o; input icpu_rty_i; input [31:0] icpu_adr_i; // // Internal i/f // input [`OR1200_BRANCHOP_WIDTH-1:0] pre_branch_op; input [`OR1200_BRANCHOP_WIDTH-1:0] branch_op; input [`OR1200_EXCEPT_WIDTH-1:0] except_type; input except_prefix; input [31:2] id_branch_addrtarget; input [31:2] ex_branch_addrtarget; input [31:0] muxed_b; input [31:0] operand_b; input flag; input flagforw; output ex_branch_taken; input except_start; input [31:0] epcr; input [31:0] spr_dat_i; input spr_pc_we; input genpc_refetch; input genpc_freeze; input no_more_dslot; // // Internal wires and regs // reg [31:2] pcreg_default; wire [31:0] pcreg_boot; reg pcreg_select; reg [31:2] pcreg; reg [31:0] pc; // Set in event of jump or taken branch reg ex_branch_taken; reg genpc_refetch_r; // // Address of insn to be fecthed // assign icpu_adr_o = !no_more_dslot & !except_start & !spr_pc_we & (icpu_rty_i | genpc_refetch) ? icpu_adr_i : {pc[31:2], 1'b0, ex_branch_taken|spr_pc_we}; // // Control access to IC subsystem // assign icpu_cycstb_o = ~(genpc_freeze | (|pre_branch_op && !icpu_rty_i)); assign icpu_sel_o = 4'b1111; assign icpu_tag_o = `OR1200_ITAG_NI; // // genpc_freeze_r // always @(posedge clk or `OR1200_RST_EVENT rst) if (rst == `OR1200_RST_VALUE) genpc_refetch_r <= 1'b0; else if (genpc_refetch) genpc_refetch_r <= 1'b1; else genpc_refetch_r <= 1'b0; // // Async calculation of new PC value. This value is used for addressing the // IC. // always @(pcreg or ex_branch_addrtarget or flag or branch_op or except_type or except_start or operand_b or epcr or spr_pc_we or spr_dat_i or except_prefix) begin casez ({spr_pc_we, except_start, branch_op}) // synopsys parallel_case {2'b00, `OR1200_BRANCHOP_NOP}: begin pc = {pcreg + 30'd1, 2'b0}; ex_branch_taken = 1'b0; end {2'b00, `OR1200_BRANCHOP_J}: begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_J: pc <= ex_branch_addrtarget %h" , $time, ex_branch_addrtarget); // synopsys translate_on `endif pc = {ex_branch_addrtarget, 2'b00}; ex_branch_taken = 1'b1; end {2'b00, `OR1200_BRANCHOP_JR}: begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_JR: pc <= operand_b %h", $time, operand_b); // synopsys translate_on `endif pc = operand_b; ex_branch_taken = 1'b1; end {2'b00, `OR1200_BRANCHOP_BF}: if (flag) begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_BF: pc <= ex_branch_addrtarget %h", $time, ex_branch_addrtarget); // synopsys translate_on `endif pc = {ex_branch_addrtarget, 2'b00}; ex_branch_taken = 1'b1; end else begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_BF: not taken", $time); // synopsys translate_on `endif pc = {pcreg + 30'd1, 2'b0}; ex_branch_taken = 1'b0; end {2'b00, `OR1200_BRANCHOP_BNF}: if (flag) begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_BNF: not taken", $time); // synopsys translate_on `endif pc = {pcreg + 30'd1, 2'b0}; ex_branch_taken = 1'b0; end else begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_BNF: pc <= ex_branch_addrtarget %h", $time, ex_branch_addrtarget); // synopsys translate_on `endif pc = {ex_branch_addrtarget, 2'b00}; ex_branch_taken = 1'b1; end {2'b00, `OR1200_BRANCHOP_RFE}: begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("%t: BRANCHOP_RFE: pc <= epcr %h", $time, epcr); // synopsys translate_on `endif pc = epcr; ex_branch_taken = 1'b1; end {2'b01, 3'b???}: begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("Starting exception: %h.", except_type); // synopsys translate_on `endif pc = {(except_prefix ? `OR1200_EXCEPT_EPH1_P : `OR1200_EXCEPT_EPH0_P), except_type, `OR1200_EXCEPT_V}; ex_branch_taken = 1'b1; end default: begin `ifdef OR1200_VERBOSE // synopsys translate_off $display("l.mtspr writing into PC: %h.", spr_dat_i); // synopsys translate_on `endif pc = spr_dat_i; ex_branch_taken = 1'b0; end endcase end // // PC register // always @(posedge clk or `OR1200_RST_EVENT rst) // default value if (rst == `OR1200_RST_VALUE) begin pcreg_default <= `OR1200_BOOT_PCREG_DEFAULT; // jb pcreg_select <= 1'b1;// select async. value due to reset state end // selected value (different from default) is written into FF after // reset state else if (pcreg_select) begin // dynamic value can only be assigned to FF out of reset! pcreg_default <= pcreg_boot[31:2]; pcreg_select <= 1'b0; // select FF value end else if (spr_pc_we) begin pcreg_default <= spr_dat_i[31:2]; end else if (no_more_dslot | except_start | !genpc_freeze & !icpu_rty_i & !genpc_refetch) begin pcreg_default <= pc[31:2]; end // select async. value for pcreg after reset - PC jumps to the address selected // after boot. assign pcreg_boot = `OR1200_BOOT_ADR; // changed JB always @(pcreg_boot or pcreg_default or pcreg_select) if (pcreg_select) // async. value is selected due to reset state pcreg = pcreg_boot[31:2]; else // FF value is selected 2nd clock after reset state pcreg = pcreg_default ; endmodule
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