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lekernel |
/*
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* Milkymist VJ SoC
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* Copyright (C) 2007, 2008, 2009, 2010 Sebastien Bourdeauducq
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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module softusb_navre #(
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parameter pmem_width = 11, /* < in 16-bit instructions */
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parameter dmem_width = 13 /* < in bytes */
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) (
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input clk,
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input rst,
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output reg pmem_ce,
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output [pmem_width-1:0] pmem_a,
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input [15:0] pmem_d,
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output reg dmem_we,
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output reg [dmem_width-1:0] dmem_a,
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input [7:0] dmem_di,
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output reg [7:0] dmem_do,
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output reg io_re,
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output reg io_we,
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output [5:0] io_a,
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output [7:0] io_do,
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input [7:0] io_di
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);
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/* Register file */
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reg [pmem_width-1:0] PC;
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reg [7:0] GPR[0:23];
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reg [15:0] U; /* < R24-R25 */
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reg [15:0] pX; /* < R26-R27 */
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reg [15:0] pY; /* < R28-R29 */
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reg [15:0] pZ; /* < R30-R31 */
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reg T, H, S, V, N, Z, C;
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/* Stack */
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reg [7:0] io_sp;
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reg [15:0] SP;
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reg push;
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reg pop;
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always @(posedge clk) begin
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if(rst) begin
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io_sp <= 8'd0;
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SP <= 16'd0;
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end else begin
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io_sp <= io_a[0] ? SP[7:0] : SP[15:8];
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if((io_a == 6'b111101) | (io_a == 6'b111110)) begin
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if(io_we) begin
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if(io_a[0])
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SP[7:0] <= io_do;
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else
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SP[15:8] <= io_do;
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end
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end
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if(push)
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SP <= SP - 16'd1;
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if(pop)
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SP <= SP + 16'd1;
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end
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end
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/* I/O mapped registers */
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parameter IO_SEL_EXT = 2'd0;
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parameter IO_SEL_STACK = 2'd1;
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parameter IO_SEL_SREG = 2'd2;
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reg [1:0] io_sel;
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always @(posedge clk) begin
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if(rst)
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io_sel <= IO_SEL_EXT;
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else begin
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case(io_a)
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6'b111101,
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6'b111110: io_sel <= IO_SEL_STACK;
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6'b111111: io_sel <= IO_SEL_SREG;
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default: io_sel <= IO_SEL_EXT;
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endcase
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end
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end
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/* Register operations */
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wire immediate = (pmem_d[14]
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| (pmem_d[15:12] == 4'b0011)) /* CPI */
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& (pmem_d[15:10] != 6'b111111); /* SBRC - SBRS */
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reg lpm_en;
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wire [4:0] Rd = lpm_en ? 5'd0 : {immediate | pmem_d[8], pmem_d[7:4]};
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wire [4:0] Rr = {pmem_d[9], pmem_d[3:0]};
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wire [7:0] K = {pmem_d[11:8], pmem_d[3:0]};
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wire [2:0] b = pmem_d[2:0];
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wire [11:0] Kl = pmem_d[11:0];
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wire [6:0] Ks = pmem_d[9:3];
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wire [1:0] Rd16 = pmem_d[5:4];
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wire [5:0] K16 = {pmem_d[7:6], pmem_d[3:0]};
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wire [5:0] q = {pmem_d[13], pmem_d[11:10], pmem_d[2:0]};
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wire [7:0] GPR_Rd8 = GPR[Rd];
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wire [7:0] GPR_Rr8 = GPR[Rr];
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reg [7:0] GPR_Rd;
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always @(*) begin
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case(Rd)
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default: GPR_Rd = GPR_Rd8;
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5'd24: GPR_Rd = U[7:0];
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5'd25: GPR_Rd = U[15:8];
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5'd26: GPR_Rd = pX[7:0];
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5'd27: GPR_Rd = pX[15:8];
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5'd28: GPR_Rd = pY[7:0];
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5'd29: GPR_Rd = pY[15:8];
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5'd30: GPR_Rd = pZ[7:0];
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5'd31: GPR_Rd = pZ[15:8];
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endcase
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end
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reg [7:0] GPR_Rr;
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always @(*) begin
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case(Rr)
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default: GPR_Rr = GPR_Rr8;
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5'd24: GPR_Rr = U[7:0];
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5'd25: GPR_Rr = U[15:8];
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5'd26: GPR_Rr = pX[7:0];
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5'd27: GPR_Rr = pX[15:8];
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5'd28: GPR_Rr = pY[7:0];
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5'd29: GPR_Rr = pY[15:8];
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5'd30: GPR_Rr = pZ[7:0];
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5'd31: GPR_Rr = pZ[15:8];
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endcase
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end
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wire GPR_Rd_b = GPR_Rd[b];
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reg [15:0] GPR_Rd16;
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always @(*) begin
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case(Rd16)
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2'd0: GPR_Rd16 = U;
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2'd1: GPR_Rd16 = pX;
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2'd2: GPR_Rd16 = pY;
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2'd3: GPR_Rd16 = pZ;
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endcase
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end
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/* Memorize values to support 16-bit instructions */
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reg regmem_ce;
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reg [4:0] Rd_r;
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reg [7:0] GPR_Rd_r;
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always @(posedge clk) begin
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if(regmem_ce)
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Rd_r <= Rd; /* < control with regmem_ce */
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GPR_Rd_r <= GPR_Rd; /* < always loaded */
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end
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/* PC */
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reg [3:0] pc_sel;
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parameter PC_SEL_NOP = 4'd0;
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parameter PC_SEL_INC = 4'd1;
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parameter PC_SEL_KL = 4'd2;
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parameter PC_SEL_KS = 4'd3;
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parameter PC_SEL_DMEML = 4'd4;
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parameter PC_SEL_DMEMH = 4'd6;
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parameter PC_SEL_DEC = 4'd7;
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parameter PC_SEL_Z = 4'd7;
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always @(posedge clk) begin
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if(rst) begin
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PC <= 0;
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end else begin
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case(pc_sel)
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PC_SEL_NOP:;
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PC_SEL_INC: PC <= PC + 1;
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// !!! WARNING !!! replace with PC <= PC + {{pmem_width-12{Kl[11]}}, Kl}; if pmem_width>12
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PC_SEL_KL: PC <= PC + Kl;
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PC_SEL_KS: PC <= PC + {{pmem_width-7{Ks[6]}}, Ks};
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PC_SEL_DMEML: PC[7:0] <= dmem_di;
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PC_SEL_DMEMH: PC[pmem_width-1:8] <= dmem_di;
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PC_SEL_DEC: PC <= PC - 1;
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PC_SEL_Z: PC <= pZ - 1;
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endcase
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end
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end
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reg pmem_selz;
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assign pmem_a = rst ? 0 : (pmem_selz ? pZ[15:1] : PC + 1);
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/* Load/store operations */
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reg [3:0] dmem_sel;
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parameter DMEM_SEL_UNDEFINED = 3'bxxx;
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parameter DMEM_SEL_X = 4'd0;
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parameter DMEM_SEL_XPLUS = 4'd1;
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parameter DMEM_SEL_XMINUS = 4'd2;
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parameter DMEM_SEL_YPLUS = 4'd3;
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parameter DMEM_SEL_YMINUS = 4'd4;
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parameter DMEM_SEL_YQ = 4'd5;
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parameter DMEM_SEL_ZPLUS = 4'd6;
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parameter DMEM_SEL_ZMINUS = 4'd7;
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parameter DMEM_SEL_ZQ = 4'd8;
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parameter DMEM_SEL_SP_R = 4'd9;
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parameter DMEM_SEL_SP_PCL = 4'd10;
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parameter DMEM_SEL_SP_PCH = 4'd11;
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parameter DMEM_SEL_PMEM = 4'd12;
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/* ALU */
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reg normal_en;
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reg lds_writeback;
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wire [4:0] write_dest = lds_writeback ? Rd_r : Rd;
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// synthesis translate_off
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integer i_rst_regf;
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// synthesis translate_on
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reg [7:0] R;
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reg writeback;
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reg update_nsz;
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reg [15:0] R16;
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reg mode16;
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always @(posedge clk) begin
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R = 8'hxx;
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writeback = 1'b0;
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update_nsz = 1'b0;
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R16 = 16'hxxxx;
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mode16 = 1'b0;
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if(rst) begin
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/*
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* Not resetting the register file enables the use of more efficient
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* distributed block RAM.
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*/
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// synthesis translate_off
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for(i_rst_regf=0;i_rst_regf<24;i_rst_regf=i_rst_regf+1)
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GPR[i_rst_regf] = 8'd0;
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U = 16'd0;
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pX = 16'd0;
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pY = 16'd0;
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pZ = 16'd0;
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// synthesis translate_on
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T = 1'b0;
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H = 1'b0;
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S = 1'b0;
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V = 1'b0;
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N = 1'b0;
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Z = 1'b0;
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C = 1'b0;
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end else begin
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if(normal_en) begin
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writeback = 1'b1;
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update_nsz = 1'b1;
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casex(pmem_d)
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| 261 |
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16'b000x_11xx_xxxx_xxxx: begin
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/* ADD - ADC */
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| 263 |
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{C, R} = GPR_Rd + GPR_Rr + (pmem_d[12] & C);
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H = (GPR_Rd[3] & GPR_Rr[3])|(GPR_Rr[3] & ~R[3])|(~R[3] & GPR_Rd[3]);
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V = (GPR_Rd[7] & GPR_Rr[7] & ~R[7])|(~GPR_Rd[7] & ~GPR_Rr[7] & R[7]);
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end
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| 267 |
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16'b000x_10xx_xxxx_xxxx, /* subtract */
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| 268 |
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16'b000x_01xx_xxxx_xxxx: /* compare */ begin
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| 269 |
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/* SUB - SBC / CP - CPC */
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| 270 |
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{C, R} = GPR_Rd - GPR_Rr - (~pmem_d[12] & C);
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| 271 |
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H = (~GPR_Rd[3] & GPR_Rr[3])|(GPR_Rr[3] & R[3])|(R[3] & ~GPR_Rd[3]);
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| 272 |
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V = (GPR_Rd[7] & ~GPR_Rr[7] & ~R[7])|(~GPR_Rd[7] & GPR_Rr[7] & R[7]);
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| 273 |
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writeback = pmem_d[11];
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| 274 |
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end
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| 275 |
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16'b010x_xxxx_xxxx_xxxx, /* subtract */
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| 276 |
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16'b0011_xxxx_xxxx_xxxx: /* compare */ begin
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| 277 |
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/* SUBI - SBCI / CPI */
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| 278 |
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{C, R} = GPR_Rd - K - (~pmem_d[12] & C);
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| 279 |
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H = (~GPR_Rd[3] & K[3])|(K[3] & R[3])|(R[3] & ~GPR_Rd[3]);
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| 280 |
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V = (GPR_Rd[7] & ~K[7] & ~R[7])|(~GPR_Rd[7] & K[7] & R[7]);
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| 281 |
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writeback = pmem_d[14];
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| 282 |
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end
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| 283 |
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16'b0010_00xx_xxxx_xxxx: begin
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| 284 |
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/* AND */
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| 285 |
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R = GPR_Rd & GPR_Rr;
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| 286 |
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V = 1'b0;
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| 287 |
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end
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| 288 |
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16'b0111_xxxx_xxxx_xxxx: begin
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| 289 |
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/* ANDI */
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| 290 |
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R = GPR_Rd & K;
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| 291 |
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V = 1'b0;
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| 292 |
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end
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| 293 |
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16'b0010_10xx_xxxx_xxxx: begin
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| 294 |
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/* OR */
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| 295 |
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R = GPR_Rd | GPR_Rr;
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| 296 |
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V = 1'b0;
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| 297 |
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end
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| 298 |
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16'b0110_xxxx_xxxx_xxxx: begin
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| 299 |
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/* ORI */
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| 300 |
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R = GPR_Rd | K;
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| 301 |
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V = 1'b0;
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| 302 |
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end
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| 303 |
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16'b0010_01xx_xxxx_xxxx: begin
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| 304 |
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/* EOR */
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| 305 |
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R = GPR_Rd ^ GPR_Rr;
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| 306 |
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V = 1'b0;
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| 307 |
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end
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| 308 |
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16'b1001_010x_xxxx_0000: begin
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| 309 |
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/* COM */
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| 310 |
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R = ~GPR_Rd;
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| 311 |
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V = 1'b0;
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| 312 |
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C = 1'b1;
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| 313 |
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end
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| 314 |
|
|
16'b1001_010x_xxxx_0001: begin
|
| 315 |
|
|
/* NEG */
|
| 316 |
|
|
{C, R} = 8'h00 - GPR_Rd;
|
| 317 |
|
|
H = R[3] | GPR_Rd[3];
|
| 318 |
|
|
V = R == 8'h80;
|
| 319 |
|
|
end
|
| 320 |
|
|
16'b1001_010x_xxxx_0011: begin
|
| 321 |
|
|
/* INC */
|
| 322 |
|
|
R = GPR_Rd + 8'd1;
|
| 323 |
|
|
V = R == 8'h80;
|
| 324 |
|
|
end
|
| 325 |
|
|
16'b1001_010x_xxxx_1010: begin
|
| 326 |
|
|
/* DEC */
|
| 327 |
|
|
R = GPR_Rd - 8'd1;
|
| 328 |
|
|
V = R == 8'h7f;
|
| 329 |
|
|
end
|
| 330 |
|
|
16'b1001_010x_xxxx_011x: begin
|
| 331 |
|
|
/* LSR - ROR */
|
| 332 |
|
|
R = {pmem_d[0] & C, GPR_Rd[7:1]};
|
| 333 |
|
|
C = GPR_Rd[0];
|
| 334 |
|
|
V = R[7] ^ GPR_Rd[0];
|
| 335 |
|
|
end
|
| 336 |
|
|
16'b1001_010x_xxxx_0101: begin
|
| 337 |
|
|
/* ASR */
|
| 338 |
|
|
R = {GPR_Rd[7], GPR_Rd[7:1]};
|
| 339 |
|
|
C = GPR_Rd[0];
|
| 340 |
|
|
V = R[7] ^ GPR_Rd[0];
|
| 341 |
|
|
end
|
| 342 |
|
|
16'b1001_010x_xxxx_0010: begin
|
| 343 |
|
|
/* SWAP */
|
| 344 |
|
|
R = {GPR_Rd[3:0], GPR_Rd[7:4]};
|
| 345 |
|
|
update_nsz = 1'b0;
|
| 346 |
|
|
end
|
| 347 |
|
|
16'b1001_010x_xxxx_1000: begin
|
| 348 |
|
|
/* BSET - BCLR */
|
| 349 |
|
|
case(pmem_d[7:4])
|
| 350 |
|
|
4'b0000: C = 1'b1;
|
| 351 |
|
|
4'b0001: Z = 1'b1;
|
| 352 |
|
|
4'b0010: N = 1'b1;
|
| 353 |
|
|
4'b0011: V = 1'b1;
|
| 354 |
|
|
4'b0100: S = 1'b1;
|
| 355 |
|
|
4'b0101: H = 1'b1;
|
| 356 |
|
|
4'b0110: T = 1'b1;
|
| 357 |
|
|
4'b1000: C = 1'b0;
|
| 358 |
|
|
4'b1001: Z = 1'b0;
|
| 359 |
|
|
4'b1010: N = 1'b0;
|
| 360 |
|
|
4'b1011: V = 1'b0;
|
| 361 |
|
|
4'b1100: S = 1'b0;
|
| 362 |
|
|
4'b1101: H = 1'b0;
|
| 363 |
|
|
4'b1110: T = 1'b0;
|
| 364 |
|
|
endcase
|
| 365 |
|
|
update_nsz = 1'b0;
|
| 366 |
|
|
writeback = 1'b0;
|
| 367 |
|
|
end
|
| 368 |
|
|
16'b1001_011x_xxxx_xxxx: begin
|
| 369 |
|
|
mode16 = 1'b1;
|
| 370 |
|
|
if(pmem_d[8]) begin
|
| 371 |
|
|
/* SBIW */
|
| 372 |
|
|
{C, R16} = GPR_Rd16 - K16;
|
| 373 |
|
|
V = GPR_Rd16[15] & ~R16[15];
|
| 374 |
|
|
end else begin
|
| 375 |
|
|
/* ADIW */
|
| 376 |
|
|
{C, R16} = GPR_Rd16 + K16;
|
| 377 |
|
|
V = ~GPR_Rd16[15] & R16[15];
|
| 378 |
|
|
end
|
| 379 |
|
|
end
|
| 380 |
|
|
/* SBR and CBR are replaced with ORI and ANDI */
|
| 381 |
|
|
/* TST is replaced with AND */
|
| 382 |
|
|
/* CLR and SER are replaced with EOR and LDI */
|
| 383 |
|
|
16'b0010_11xx_xxxx_xxxx: begin
|
| 384 |
|
|
/* MOV */
|
| 385 |
|
|
R = GPR_Rr;
|
| 386 |
|
|
update_nsz = 1'b0;
|
| 387 |
|
|
end
|
| 388 |
|
|
16'b1110_xxxx_xxxx_xxxx: begin
|
| 389 |
|
|
/* LDI */
|
| 390 |
|
|
R = K;
|
| 391 |
|
|
update_nsz = 1'b0;
|
| 392 |
|
|
end
|
| 393 |
|
|
/* LSL is replaced with ADD */
|
| 394 |
|
|
/* ROL is replaced with ADC */
|
| 395 |
|
|
16'b1111_10xx_xxxx_xxxx: begin
|
| 396 |
|
|
if(pmem_d[9]) begin
|
| 397 |
|
|
/* BST */
|
| 398 |
|
|
T = GPR_Rd_b;
|
| 399 |
|
|
writeback = 1'b0;
|
| 400 |
|
|
end else begin
|
| 401 |
|
|
/* BLD */
|
| 402 |
|
|
case(b)
|
| 403 |
|
|
3'd0: R = {GPR_Rd[7:1], T};
|
| 404 |
|
|
3'd1: R = {GPR_Rd[7:2], T, GPR_Rd[0]};
|
| 405 |
|
|
3'd2: R = {GPR_Rd[7:3], T, GPR_Rd[1:0]};
|
| 406 |
|
|
3'd3: R = {GPR_Rd[7:4], T, GPR_Rd[2:0]};
|
| 407 |
|
|
3'd4: R = {GPR_Rd[7:5], T, GPR_Rd[3:0]};
|
| 408 |
|
|
3'd5: R = {GPR_Rd[7:6], T, GPR_Rd[4:0]};
|
| 409 |
|
|
3'd6: R = {GPR_Rd[7], T, GPR_Rd[5:0]};
|
| 410 |
|
|
3'd7: R = {T, GPR_Rd[6:0]};
|
| 411 |
|
|
endcase
|
| 412 |
|
|
end
|
| 413 |
|
|
update_nsz = 1'b0;
|
| 414 |
|
|
end
|
| 415 |
|
|
/* SEC, CLC, SEN, CLN, SEZ, CLZ, SEI, CLI, SES, CLS, SEV, CLV, SET, CLT, SEH, CLH
|
| 416 |
|
|
* are replaced with BSET and BCLR */
|
| 417 |
|
|
16'b0000_0000_0000_0000: begin
|
| 418 |
|
|
/* NOP */
|
| 419 |
|
|
update_nsz = 1'b0;
|
| 420 |
|
|
writeback = 1'b0;
|
| 421 |
|
|
end
|
| 422 |
|
|
/* SLEEP is not implemented */
|
| 423 |
|
|
/* WDR is not implemented */
|
| 424 |
|
|
16'b1001_00xx_xxxx_1111, /* PUSH/POP */
|
| 425 |
|
|
16'b1001_00xx_xxxx_1100, /* X */
|
| 426 |
|
|
16'b1001_00xx_xxxx_1101, /* X+ */
|
| 427 |
|
|
16'b1001_00xx_xxxx_1110, /* -X */
|
| 428 |
|
|
16'b1001_00xx_xxxx_1001, /* Y+ */
|
| 429 |
|
|
16'b1001_00xx_xxxx_1010, /* -Y */
|
| 430 |
|
|
16'b10x0_xxxx_xxxx_1xxx, /* Y+q */
|
| 431 |
|
|
16'b1001_00xx_xxxx_0001, /* Z+ */
|
| 432 |
|
|
16'b1001_00xx_xxxx_0010, /* -Z */
|
| 433 |
|
|
16'b10x0_xxxx_xxxx_0xxx: /* Z+q */
|
| 434 |
|
|
begin
|
| 435 |
|
|
/* LD - POP (run from state WRITEBACK) */
|
| 436 |
|
|
R = dmem_di;
|
| 437 |
|
|
update_nsz = 1'b0;
|
| 438 |
|
|
end
|
| 439 |
|
|
16'b1011_0xxx_xxxx_xxxx: begin
|
| 440 |
|
|
/* IN (run from state WRITEBACK) */
|
| 441 |
|
|
case(io_sel)
|
| 442 |
|
|
IO_SEL_EXT: R = io_di;
|
| 443 |
|
|
IO_SEL_STACK: R = io_sp;
|
| 444 |
|
|
IO_SEL_SREG: R = {1'b0, T, H, S, V, N, Z, C};
|
| 445 |
|
|
default: R = 8'hxx;
|
| 446 |
|
|
endcase
|
| 447 |
|
|
update_nsz = 1'b0;
|
| 448 |
|
|
end
|
| 449 |
|
|
endcase
|
| 450 |
|
|
end /* if(normal_en) */
|
| 451 |
|
|
if(lds_writeback) begin
|
| 452 |
|
|
R = dmem_di;
|
| 453 |
|
|
writeback = 1'b1;
|
| 454 |
|
|
end
|
| 455 |
|
|
if(lpm_en) begin
|
| 456 |
|
|
R = pZ[0] ? pmem_d[15:8] : pmem_d[7:0];
|
| 457 |
|
|
writeback = 1'b1;
|
| 458 |
|
|
end
|
| 459 |
|
|
if(update_nsz) begin
|
| 460 |
|
|
N = mode16 ? R16[15] : R[7];
|
| 461 |
|
|
S = N ^ V;
|
| 462 |
|
|
Z = mode16 ? R16 == 16'h0000 : R == 8'h00;
|
| 463 |
|
|
end
|
| 464 |
|
|
if(io_we & (io_a == 6'b111111))
|
| 465 |
|
|
{T, H, S, V, N, Z, C} = io_do[6:0];
|
| 466 |
|
|
if(writeback) begin
|
| 467 |
|
|
if(mode16) begin
|
| 468 |
|
|
// synthesis translate_off
|
| 469 |
|
|
//$display("REG WRITE(16): %d < %d", Rd16, R16);
|
| 470 |
|
|
// synthesis translate_on
|
| 471 |
|
|
case(Rd16)
|
| 472 |
|
|
2'd0: U = R16;
|
| 473 |
|
|
2'd1: pX = R16;
|
| 474 |
|
|
2'd2: pY = R16;
|
| 475 |
|
|
2'd3: pZ = R16;
|
| 476 |
|
|
endcase
|
| 477 |
|
|
end else begin
|
| 478 |
|
|
// synthesis translate_off
|
| 479 |
|
|
//$display("REG WRITE: %d < %d", Rd, R);
|
| 480 |
|
|
// synthesis translate_on
|
| 481 |
|
|
case(write_dest)
|
| 482 |
|
|
default: GPR[write_dest] = R;
|
| 483 |
|
|
5'd24: U[7:0] = R;
|
| 484 |
|
|
5'd25: U[15:8] = R;
|
| 485 |
|
|
5'd26: pX[7:0] = R;
|
| 486 |
|
|
5'd27: pX[15:8] = R;
|
| 487 |
|
|
5'd28: pY[7:0] = R;
|
| 488 |
|
|
5'd29: pY[15:8] = R;
|
| 489 |
|
|
5'd30: pZ[7:0] = R;
|
| 490 |
|
|
5'd31: pZ[15:8] = R;
|
| 491 |
|
|
endcase
|
| 492 |
|
|
end
|
| 493 |
|
|
end else begin /* if(writeback) */
|
| 494 |
|
|
case(dmem_sel)
|
| 495 |
|
|
DMEM_SEL_XPLUS: pX = pX + 16'd1;
|
| 496 |
|
|
DMEM_SEL_XMINUS: pX = pX - 16'd1;
|
| 497 |
|
|
DMEM_SEL_YPLUS: pY = pY + 16'd1;
|
| 498 |
|
|
DMEM_SEL_YMINUS: pY = pY - 16'd1;
|
| 499 |
|
|
DMEM_SEL_ZPLUS: pZ = pZ + 16'd1;
|
| 500 |
|
|
DMEM_SEL_ZMINUS: pZ = pZ - 16'd1;
|
| 501 |
|
|
default:;
|
| 502 |
|
|
endcase
|
| 503 |
|
|
end
|
| 504 |
|
|
end /* if(sys_rst) ... else */
|
| 505 |
|
|
end
|
| 506 |
|
|
|
| 507 |
|
|
/* I/O port */
|
| 508 |
|
|
assign io_a = {pmem_d[10:9], pmem_d[3:0]};
|
| 509 |
|
|
assign io_do = GPR_Rd;
|
| 510 |
|
|
|
| 511 |
|
|
/* Data memory */
|
| 512 |
|
|
always @(*) begin
|
| 513 |
|
|
case(dmem_sel)
|
| 514 |
|
|
DMEM_SEL_X,
|
| 515 |
|
|
DMEM_SEL_XPLUS: dmem_a = pX;
|
| 516 |
|
|
DMEM_SEL_XMINUS: dmem_a = pX - 16'd1;
|
| 517 |
|
|
DMEM_SEL_YPLUS: dmem_a = pY;
|
| 518 |
|
|
DMEM_SEL_YMINUS: dmem_a = pY - 16'd1;
|
| 519 |
|
|
DMEM_SEL_YQ: dmem_a = pY + q;
|
| 520 |
|
|
DMEM_SEL_ZPLUS: dmem_a = pZ;
|
| 521 |
|
|
DMEM_SEL_ZMINUS: dmem_a = pZ - 16'd1;
|
| 522 |
|
|
DMEM_SEL_ZQ: dmem_a = pZ + q;
|
| 523 |
|
|
DMEM_SEL_SP_R,
|
| 524 |
|
|
DMEM_SEL_SP_PCL,
|
| 525 |
|
|
DMEM_SEL_SP_PCH: dmem_a = SP + pop;
|
| 526 |
|
|
DMEM_SEL_PMEM: dmem_a = pmem_d;
|
| 527 |
|
|
default: dmem_a = {dmem_width{1'bx}};
|
| 528 |
|
|
endcase
|
| 529 |
|
|
end
|
| 530 |
|
|
|
| 531 |
|
|
wire [pmem_width-1:0] PC_inc = PC + 1;
|
| 532 |
|
|
always @(*) begin
|
| 533 |
|
|
case(dmem_sel)
|
| 534 |
|
|
DMEM_SEL_X,
|
| 535 |
|
|
DMEM_SEL_XMINUS,
|
| 536 |
|
|
DMEM_SEL_YMINUS,
|
| 537 |
|
|
DMEM_SEL_YQ,
|
| 538 |
|
|
DMEM_SEL_ZMINUS,
|
| 539 |
|
|
DMEM_SEL_ZQ,
|
| 540 |
|
|
DMEM_SEL_SP_R: dmem_do = GPR_Rd;
|
| 541 |
|
|
DMEM_SEL_SP_PCL: dmem_do = PC_inc[7:0];
|
| 542 |
|
|
DMEM_SEL_SP_PCH: dmem_do = PC_inc[pmem_width-1:8];
|
| 543 |
|
|
DMEM_SEL_PMEM: dmem_do = GPR_Rd_r;
|
| 544 |
|
|
default: dmem_do = 8'hxx;
|
| 545 |
|
|
endcase
|
| 546 |
|
|
end
|
| 547 |
|
|
|
| 548 |
|
|
/* Multi-cycle operation sequencer */
|
| 549 |
|
|
|
| 550 |
|
|
wire reg_equal = GPR_Rd == GPR_Rr;
|
| 551 |
|
|
|
| 552 |
|
|
reg sreg_read;
|
| 553 |
|
|
always @(*) begin
|
| 554 |
|
|
case(b)
|
| 555 |
|
|
3'd0: sreg_read = C;
|
| 556 |
|
|
3'd1: sreg_read = Z;
|
| 557 |
|
|
3'd2: sreg_read = N;
|
| 558 |
|
|
3'd3: sreg_read = V;
|
| 559 |
|
|
3'd4: sreg_read = S;
|
| 560 |
|
|
3'd5: sreg_read = H;
|
| 561 |
|
|
3'd6: sreg_read = T;
|
| 562 |
|
|
3'd7: sreg_read = 1'b0;
|
| 563 |
|
|
endcase
|
| 564 |
|
|
end
|
| 565 |
|
|
|
| 566 |
|
|
reg [3:0] state;
|
| 567 |
|
|
reg [3:0] next_state;
|
| 568 |
|
|
|
| 569 |
|
|
parameter NORMAL = 4'd0;
|
| 570 |
|
|
parameter RCALL = 4'd1;
|
| 571 |
|
|
parameter ICALL = 4'd2;
|
| 572 |
|
|
parameter STALL = 4'd3;
|
| 573 |
|
|
parameter RET1 = 4'd4;
|
| 574 |
|
|
parameter RET2 = 4'd5;
|
| 575 |
|
|
parameter RET3 = 4'd6;
|
| 576 |
|
|
parameter LPM = 4'd7;
|
| 577 |
|
|
parameter STS = 4'd8;
|
| 578 |
|
|
parameter LDS1 = 4'd9;
|
| 579 |
|
|
parameter LDS2 = 4'd10;
|
| 580 |
|
|
parameter SKIP = 4'd11;
|
| 581 |
|
|
parameter WRITEBACK = 4'd12;
|
| 582 |
|
|
|
| 583 |
|
|
always @(posedge clk) begin
|
| 584 |
|
|
if(rst)
|
| 585 |
|
|
state <= NORMAL;
|
| 586 |
|
|
else
|
| 587 |
|
|
state <= next_state;
|
| 588 |
|
|
end
|
| 589 |
|
|
|
| 590 |
|
|
always @(*) begin
|
| 591 |
|
|
next_state = state;
|
| 592 |
|
|
|
| 593 |
|
|
pmem_ce = rst;
|
| 594 |
|
|
|
| 595 |
|
|
pc_sel = PC_SEL_NOP;
|
| 596 |
|
|
normal_en = 1'b0;
|
| 597 |
|
|
lpm_en = 1'b0;
|
| 598 |
|
|
|
| 599 |
|
|
io_re = 1'b0;
|
| 600 |
|
|
io_we = 1'b0;
|
| 601 |
|
|
|
| 602 |
|
|
dmem_we = 1'b0;
|
| 603 |
|
|
dmem_sel = DMEM_SEL_UNDEFINED;
|
| 604 |
|
|
|
| 605 |
|
|
push = 1'b0;
|
| 606 |
|
|
pop = 1'b0;
|
| 607 |
|
|
|
| 608 |
|
|
pmem_selz = 1'b0;
|
| 609 |
|
|
|
| 610 |
|
|
regmem_ce = 1'b1;
|
| 611 |
|
|
lds_writeback = 1'b0;
|
| 612 |
|
|
|
| 613 |
|
|
case(state)
|
| 614 |
|
|
NORMAL: begin
|
| 615 |
|
|
casex(pmem_d)
|
| 616 |
|
|
16'b1100_xxxx_xxxx_xxxx: begin
|
| 617 |
|
|
/* RJMP */
|
| 618 |
|
|
pc_sel = PC_SEL_KL;
|
| 619 |
|
|
next_state = STALL;
|
| 620 |
|
|
end
|
| 621 |
|
|
16'b1101_xxxx_xxxx_xxxx: begin
|
| 622 |
|
|
/* RCALL */
|
| 623 |
|
|
/* TODO: in which order should we push the bytes? */
|
| 624 |
|
|
dmem_sel = DMEM_SEL_SP_PCL;
|
| 625 |
|
|
dmem_we = 1'b1;
|
| 626 |
|
|
push = 1'b1;
|
| 627 |
|
|
next_state = RCALL;
|
| 628 |
|
|
end
|
| 629 |
|
|
16'b0001_00xx_xxxx_xxxx: begin
|
| 630 |
|
|
/* CPSE */
|
| 631 |
|
|
pc_sel = PC_SEL_INC;
|
| 632 |
|
|
pmem_ce = 1'b1;
|
| 633 |
|
|
if(reg_equal)
|
| 634 |
|
|
next_state = SKIP;
|
| 635 |
|
|
end
|
| 636 |
|
|
16'b1111_11xx_xxxx_xxxx: begin
|
| 637 |
|
|
/* SBRC - SBRS */
|
| 638 |
|
|
pc_sel = PC_SEL_INC;
|
| 639 |
|
|
pmem_ce = 1'b1;
|
| 640 |
|
|
if(GPR_Rd_b == pmem_d[9])
|
| 641 |
|
|
next_state = SKIP;
|
| 642 |
|
|
end
|
| 643 |
|
|
/* SBIC, SBIS, SBI, CBI are not implemented */
|
| 644 |
|
|
16'b1111_0xxx_xxxx_xxxx: begin
|
| 645 |
|
|
/* BRBS - BRBC */
|
| 646 |
|
|
pmem_ce = 1'b1;
|
| 647 |
|
|
if(sreg_read ^ pmem_d[10]) begin
|
| 648 |
|
|
pc_sel = PC_SEL_KS;
|
| 649 |
|
|
next_state = STALL;
|
| 650 |
|
|
end else
|
| 651 |
|
|
pc_sel = PC_SEL_INC;
|
| 652 |
|
|
end
|
| 653 |
|
|
/* BREQ, BRNE, BRCS, BRCC, BRSH, BRLO, BRMI, BRPL, BRGE, BRLT,
|
| 654 |
|
|
* BRHS, BRHC, BRTS, BRTC, BRVS, BRVC, BRIE, BRID are replaced
|
| 655 |
|
|
* with BRBS/BRBC */
|
| 656 |
|
|
16'b1001_00xx_xxxx_1100, /* X */
|
| 657 |
|
|
16'b1001_00xx_xxxx_1101, /* X+ */
|
| 658 |
|
|
16'b1001_00xx_xxxx_1110, /* -X */
|
| 659 |
|
|
16'b1001_00xx_xxxx_1001, /* Y+ */
|
| 660 |
|
|
16'b1001_00xx_xxxx_1010, /* -Y */
|
| 661 |
|
|
16'b10x0_xxxx_xxxx_1xxx, /* Y+q */
|
| 662 |
|
|
16'b1001_00xx_xxxx_0001, /* Z+ */
|
| 663 |
|
|
16'b1001_00xx_xxxx_0010, /* -Z */
|
| 664 |
|
|
16'b10x0_xxxx_xxxx_0xxx: /* Z+q */
|
| 665 |
|
|
begin
|
| 666 |
|
|
casex({pmem_d[12], pmem_d[3:0]})
|
| 667 |
|
|
5'b1_1100: dmem_sel = DMEM_SEL_X;
|
| 668 |
|
|
5'b1_1101: dmem_sel = DMEM_SEL_XPLUS;
|
| 669 |
|
|
5'b1_1110: dmem_sel = DMEM_SEL_XMINUS;
|
| 670 |
|
|
5'b1_1001: dmem_sel = DMEM_SEL_YPLUS;
|
| 671 |
|
|
5'b1_1010: dmem_sel = DMEM_SEL_YMINUS;
|
| 672 |
|
|
5'b0_1xxx: dmem_sel = DMEM_SEL_YQ;
|
| 673 |
|
|
5'b1_0001: dmem_sel = DMEM_SEL_ZPLUS;
|
| 674 |
|
|
5'b1_0010: dmem_sel = DMEM_SEL_ZMINUS;
|
| 675 |
|
|
5'b0_0xxx: dmem_sel = DMEM_SEL_ZQ;
|
| 676 |
|
|
endcase
|
| 677 |
|
|
if(pmem_d[9]) begin
|
| 678 |
|
|
/* ST */
|
| 679 |
|
|
pc_sel = PC_SEL_INC;
|
| 680 |
|
|
pmem_ce = 1'b1;
|
| 681 |
|
|
dmem_we = 1'b1;
|
| 682 |
|
|
end else begin
|
| 683 |
|
|
/* LD */
|
| 684 |
|
|
next_state = WRITEBACK;
|
| 685 |
|
|
end
|
| 686 |
|
|
end
|
| 687 |
|
|
16'b1011_0xxx_xxxx_xxxx: begin
|
| 688 |
|
|
/* IN */
|
| 689 |
|
|
io_re = 1'b1;
|
| 690 |
|
|
next_state = WRITEBACK;
|
| 691 |
|
|
end
|
| 692 |
|
|
16'b1011_1xxx_xxxx_xxxx: begin
|
| 693 |
|
|
/* OUT */
|
| 694 |
|
|
io_we = 1'b1;
|
| 695 |
|
|
pc_sel = PC_SEL_INC;
|
| 696 |
|
|
pmem_ce = 1'b1;
|
| 697 |
|
|
end
|
| 698 |
|
|
16'b1001_00xx_xxxx_xxxx: begin
|
| 699 |
|
|
if(pmem_d[3:0] == 4'hf) begin
|
| 700 |
|
|
if(pmem_d[9]) begin
|
| 701 |
|
|
/* PUSH */
|
| 702 |
|
|
push = 1'b1;
|
| 703 |
|
|
dmem_sel = DMEM_SEL_SP_R;
|
| 704 |
|
|
dmem_we = 1'b1;
|
| 705 |
|
|
pc_sel = PC_SEL_INC;
|
| 706 |
|
|
pmem_ce = 1'b1;
|
| 707 |
|
|
end else begin
|
| 708 |
|
|
/* POP */
|
| 709 |
|
|
pop = 1'b1;
|
| 710 |
|
|
dmem_sel = DMEM_SEL_SP_R;
|
| 711 |
|
|
next_state = WRITEBACK;
|
| 712 |
|
|
end
|
| 713 |
|
|
end else if(pmem_d[3:0] == 4'h0) begin
|
| 714 |
|
|
pc_sel = PC_SEL_INC;
|
| 715 |
|
|
pmem_ce = 1'b1;
|
| 716 |
|
|
if(pmem_d[9])
|
| 717 |
|
|
/* STS */
|
| 718 |
|
|
next_state = STS;
|
| 719 |
|
|
else
|
| 720 |
|
|
/* LDS */
|
| 721 |
|
|
next_state = LDS1;
|
| 722 |
|
|
end
|
| 723 |
|
|
end
|
| 724 |
|
|
16'b1001_0101_000x_1000: begin
|
| 725 |
|
|
/* RET - RETI (treated as RET) */
|
| 726 |
|
|
/* TODO: in which order should we pop the bytes? */
|
| 727 |
|
|
dmem_sel = DMEM_SEL_SP_PCH;
|
| 728 |
|
|
pop = 1'b1;
|
| 729 |
|
|
next_state = RET1;
|
| 730 |
|
|
end
|
| 731 |
|
|
16'b1001_0101_1100_1000: begin
|
| 732 |
|
|
/* LPM */
|
| 733 |
|
|
pmem_selz = 1'b1;
|
| 734 |
|
|
pmem_ce = 1'b1;
|
| 735 |
|
|
next_state = LPM;
|
| 736 |
|
|
end
|
| 737 |
|
|
16'b1001_0100_0000_1001: begin
|
| 738 |
|
|
/* IJMP */
|
| 739 |
|
|
pc_sel = PC_SEL_Z;
|
| 740 |
|
|
next_state = STALL;
|
| 741 |
|
|
end
|
| 742 |
|
|
16'b1001_0101_0000_1001: begin
|
| 743 |
|
|
/* ICALL */
|
| 744 |
|
|
/* TODO: in which order should we push the bytes? */
|
| 745 |
|
|
dmem_sel = DMEM_SEL_SP_PCL;
|
| 746 |
|
|
dmem_we = 1'b1;
|
| 747 |
|
|
push = 1'b1;
|
| 748 |
|
|
next_state = ICALL;
|
| 749 |
|
|
end
|
| 750 |
|
|
default: begin
|
| 751 |
|
|
pc_sel = PC_SEL_INC;
|
| 752 |
|
|
normal_en = 1'b1;
|
| 753 |
|
|
pmem_ce = 1'b1;
|
| 754 |
|
|
end
|
| 755 |
|
|
endcase
|
| 756 |
|
|
end
|
| 757 |
|
|
RCALL: begin
|
| 758 |
|
|
dmem_sel = DMEM_SEL_SP_PCH;
|
| 759 |
|
|
dmem_we = 1'b1;
|
| 760 |
|
|
push = 1'b1;
|
| 761 |
|
|
pc_sel = PC_SEL_KL;
|
| 762 |
|
|
next_state = STALL;
|
| 763 |
|
|
end
|
| 764 |
|
|
ICALL: begin
|
| 765 |
|
|
dmem_sel = DMEM_SEL_SP_PCH;
|
| 766 |
|
|
dmem_we = 1'b1;
|
| 767 |
|
|
push = 1'b1;
|
| 768 |
|
|
pc_sel = PC_SEL_Z;
|
| 769 |
|
|
next_state = STALL;
|
| 770 |
|
|
end
|
| 771 |
|
|
RET1: begin
|
| 772 |
|
|
pc_sel = PC_SEL_DMEMH;
|
| 773 |
|
|
dmem_sel = DMEM_SEL_SP_PCL;
|
| 774 |
|
|
pop = 1'b1;
|
| 775 |
|
|
next_state = RET2;
|
| 776 |
|
|
end
|
| 777 |
|
|
RET2: begin
|
| 778 |
|
|
pc_sel = PC_SEL_DMEML;
|
| 779 |
|
|
next_state = RET3;
|
| 780 |
|
|
end
|
| 781 |
|
|
RET3: begin
|
| 782 |
|
|
pc_sel = PC_SEL_DEC;
|
| 783 |
|
|
next_state = STALL;
|
| 784 |
|
|
end
|
| 785 |
|
|
LPM: begin
|
| 786 |
|
|
lpm_en = 1'b1;
|
| 787 |
|
|
pc_sel = PC_SEL_INC;
|
| 788 |
|
|
pmem_ce = 1'b1;
|
| 789 |
|
|
next_state = NORMAL;
|
| 790 |
|
|
end
|
| 791 |
|
|
STS: begin
|
| 792 |
|
|
pc_sel = PC_SEL_INC;
|
| 793 |
|
|
pmem_ce = 1'b1;
|
| 794 |
|
|
dmem_sel = DMEM_SEL_PMEM;
|
| 795 |
|
|
dmem_we = 1'b1;
|
| 796 |
|
|
next_state = NORMAL;
|
| 797 |
|
|
end
|
| 798 |
|
|
LDS1: begin
|
| 799 |
|
|
dmem_sel = DMEM_SEL_PMEM;
|
| 800 |
|
|
regmem_ce = 1'b0;
|
| 801 |
|
|
next_state = LDS2;
|
| 802 |
|
|
end
|
| 803 |
|
|
LDS2: begin
|
| 804 |
|
|
pc_sel = PC_SEL_INC;
|
| 805 |
|
|
pmem_ce = 1'b1;
|
| 806 |
|
|
normal_en = 1'b1;
|
| 807 |
|
|
lds_writeback = 1'b1;
|
| 808 |
|
|
next_state = NORMAL;
|
| 809 |
|
|
end
|
| 810 |
|
|
SKIP: begin
|
| 811 |
|
|
pc_sel = PC_SEL_INC;
|
| 812 |
|
|
pmem_ce = 1'b1;
|
| 813 |
|
|
/* test for STS and LDS */
|
| 814 |
|
|
if((pmem_d[15:10] == 6'b100100) & (pmem_d[3:0] == 4'h0))
|
| 815 |
|
|
next_state = STALL; /* 2-word instruction, skip the second word as well */
|
| 816 |
|
|
else
|
| 817 |
|
|
next_state = NORMAL; /* 1-word instruction */
|
| 818 |
|
|
end
|
| 819 |
|
|
STALL: begin
|
| 820 |
|
|
pc_sel = PC_SEL_INC;
|
| 821 |
|
|
pmem_ce = 1'b1;
|
| 822 |
|
|
next_state = NORMAL;
|
| 823 |
|
|
end
|
| 824 |
|
|
WRITEBACK: begin
|
| 825 |
|
|
pmem_ce = 1'b1;
|
| 826 |
|
|
pc_sel = PC_SEL_INC;
|
| 827 |
|
|
normal_en = 1'b1;
|
| 828 |
|
|
next_state = NORMAL;
|
| 829 |
|
|
end
|
| 830 |
|
|
endcase
|
| 831 |
|
|
end
|
| 832 |
|
|
|
| 833 |
|
|
endmodule
|
