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[/] [zipcpu/] [trunk/] [rtl/] [core/] [memops.v] - Rev 205
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//////////////////////////////////////////////////////////////////////////////// // // Filename: memops.v // // Project: Zip CPU -- a small, lightweight, RISC CPU soft core // // Purpose: A memory unit to support a CPU. // // In the interests of code simplicity, this memory operator is // susceptible to unknown results should a new command be sent to it // before it completes the last one. Unpredictable results might then // occurr. // // 20150919 -- Added support for handling BUS ERR's (i.e., the WB // error signal). // // Creator: Dan Gisselquist, Ph.D. // Gisselquist Technology, LLC // //////////////////////////////////////////////////////////////////////////////// // // Copyright (C) 2015,2017, Gisselquist Technology, LLC // // This program is free software (firmware): you can redistribute it and/or // modify it under the terms of the GNU General Public License as published // by the Free Software Foundation, either version 3 of the License, or (at // your option) any later version. // // This program is distributed in the hope that it will be useful, but WITHOUT // ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // You should have received a copy of the GNU General Public License along // with this program. (It's in the $(ROOT)/doc directory. Run make with no // target there if the PDF file isn't present.) If not, see // <http://www.gnu.org/licenses/> for a copy. // // License: GPL, v3, as defined and found on www.gnu.org, // http://www.gnu.org/licenses/gpl.html // // //////////////////////////////////////////////////////////////////////////////// // // module memops(i_clk, i_rst, i_stb, i_lock, i_op, i_addr, i_data, i_oreg, o_busy, o_valid, o_err, o_wreg, o_result, o_wb_cyc_gbl, o_wb_cyc_lcl, o_wb_stb_gbl, o_wb_stb_lcl, o_wb_we, o_wb_addr, o_wb_data, o_wb_sel, i_wb_ack, i_wb_stall, i_wb_err, i_wb_data); parameter ADDRESS_WIDTH=30, IMPLEMENT_LOCK=0, WITH_LOCAL_BUS=0; localparam AW=ADDRESS_WIDTH; input i_clk, i_rst; input i_stb, i_lock; // CPU interface input [2:0] i_op; input [31:0] i_addr; input [31:0] i_data; input [4:0] i_oreg; // CPU outputs output wire o_busy; output reg o_valid; output reg o_err; output reg [4:0] o_wreg; output reg [31:0] o_result; // Wishbone outputs output wire o_wb_cyc_gbl; output reg o_wb_stb_gbl; output wire o_wb_cyc_lcl; output reg o_wb_stb_lcl; output reg o_wb_we; output reg [(AW-1):0] o_wb_addr; output reg [31:0] o_wb_data; output reg [3:0] o_wb_sel; // Wishbone inputs input i_wb_ack, i_wb_stall, i_wb_err; input [31:0] i_wb_data; reg r_wb_cyc_gbl, r_wb_cyc_lcl; wire gbl_stb, lcl_stb; assign lcl_stb = (i_stb)&&(WITH_LOCAL_BUS!=0)&&(i_addr[31:24]==8'hff); assign gbl_stb = (i_stb)&&((WITH_LOCAL_BUS==0)||(i_addr[31:24]!=8'hff)); initial r_wb_cyc_gbl = 1'b0; initial r_wb_cyc_lcl = 1'b0; always @(posedge i_clk) if (i_rst) begin r_wb_cyc_gbl <= 1'b0; r_wb_cyc_lcl <= 1'b0; end else if ((r_wb_cyc_gbl)||(r_wb_cyc_lcl)) begin if ((i_wb_ack)||(i_wb_err)) begin r_wb_cyc_gbl <= 1'b0; r_wb_cyc_lcl <= 1'b0; end end else if (i_stb) // New memory operation begin // Grab the wishbone r_wb_cyc_lcl <= lcl_stb; r_wb_cyc_gbl <= gbl_stb; end always @(posedge i_clk) if (o_wb_cyc_gbl) o_wb_stb_gbl <= (o_wb_stb_gbl)&&(i_wb_stall); else o_wb_stb_gbl <= gbl_stb; // Grab wishbone on new operation always @(posedge i_clk) if (o_wb_cyc_lcl) o_wb_stb_lcl <= (o_wb_stb_lcl)&&(i_wb_stall); else o_wb_stb_lcl <= lcl_stb; // Grab wishbone on new operation reg [3:0] r_op; always @(posedge i_clk) if (i_stb) begin o_wb_we <= i_op[0]; casez({ i_op[2:1], i_addr[1:0] }) `ifdef ZERO_ON_IDLE 4'b100?: o_wb_data <= { i_data[15:0], 16'h00 }; 4'b101?: o_wb_data <= { 16'h00, i_data[15:0] }; 4'b1100: o_wb_data <= { i_data[7:0], 24'h00 }; 4'b1101: o_wb_data <= { 8'h00, i_data[7:0], 16'h00 }; 4'b1110: o_wb_data <= { 16'h00, i_data[7:0], 8'h00 }; 4'b1111: o_wb_data <= { 24'h00, i_data[7:0] }; `else 4'b10??: o_wb_data <= { (2){ i_data[15:0] } }; 4'b11??: o_wb_data <= { (4){ i_data[7:0] } }; `endif default: o_wb_data <= i_data; endcase o_wb_addr <= i_addr[(AW+1):2]; `ifdef SET_SEL_ON_READ if (i_op[0] == 1'b0) o_wb_sel <= 4'hf; else `endif casez({ i_op[2:1], i_addr[1:0] }) 4'b01??: o_wb_sel <= 4'b1111; 4'b100?: o_wb_sel <= 4'b1100; 4'b101?: o_wb_sel <= 4'b0011; 4'b1100: o_wb_sel <= 4'b1000; 4'b1101: o_wb_sel <= 4'b0100; 4'b1110: o_wb_sel <= 4'b0010; 4'b1111: o_wb_sel <= 4'b0001; default: o_wb_sel <= 4'b1111; endcase r_op <= { i_op[2:1] , i_addr[1:0] }; end `ifdef ZERO_ON_IDLE else if ((!o_wb_cyc_gbl)&&(!o_wb_cyc_lcl)) begin o_wb_we <= 1'b0; o_wb_addr <= 0; o_wb_data <= 32'h0; o_wb_sel <= 4'h0; end `endif initial o_valid = 1'b0; always @(posedge i_clk) o_valid <= (!i_rst)&&((o_wb_cyc_gbl)||(o_wb_cyc_lcl))&&(i_wb_ack)&&(~o_wb_we); initial o_err = 1'b0; always @(posedge i_clk) o_err <= (!i_rst)&&((o_wb_cyc_gbl)||(o_wb_cyc_lcl))&&(i_wb_err); assign o_busy = (o_wb_cyc_gbl)||(o_wb_cyc_lcl); always @(posedge i_clk) if (i_stb) o_wreg <= i_oreg; always @(posedge i_clk) `ifdef ZERO_ON_IDLE if (!i_wb_ack) o_result <= 32'h0; else `endif casez(r_op) 4'b01??: o_result <= i_wb_data; 4'b100?: o_result <= { 16'h00, i_wb_data[31:16] }; 4'b101?: o_result <= { 16'h00, i_wb_data[15: 0] }; 4'b1100: o_result <= { 24'h00, i_wb_data[31:24] }; 4'b1101: o_result <= { 24'h00, i_wb_data[23:16] }; 4'b1110: o_result <= { 24'h00, i_wb_data[15: 8] }; 4'b1111: o_result <= { 24'h00, i_wb_data[ 7: 0] }; default: o_result <= i_wb_data; endcase generate if (IMPLEMENT_LOCK != 0) begin reg lock_gbl, lock_lcl; initial lock_gbl = 1'b0; initial lock_lcl = 1'b0; always @(posedge i_clk) begin lock_gbl <= (i_lock)&&((r_wb_cyc_gbl)||(lock_gbl)); lock_lcl <= (i_lock)&&((r_wb_cyc_lcl)||(lock_lcl)); end assign o_wb_cyc_gbl = (r_wb_cyc_gbl)||(lock_gbl); assign o_wb_cyc_lcl = (r_wb_cyc_lcl)||(lock_lcl); end else begin assign o_wb_cyc_gbl = (r_wb_cyc_gbl); assign o_wb_cyc_lcl = (r_wb_cyc_lcl); end endgenerate endmodule
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