X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/960947a70a85ad40fe2569500806552d11f1e02d..326fd4c33d4331252af93af8ee3fe5dbb7ff0d3f:/Decode.v diff --git a/Decode.v b/Decode.v index 5690062..fd8554b 100644 --- a/Decode.v +++ b/Decode.v @@ -2,154 +2,207 @@ module Decode( input clk, - input [31:0] ansn, + input [31:0] insn, input [31:0] inpc, - input [31:0] cps_in, + input [31:0] incpsr, output reg [31:0] op0, output reg [31:0] op1, output reg [31:0] op2, - output reg [31:0] cps_out, + output reg [31:0] outcpsr, - output [3:0] regsel0, - output [3:0] regsel1, - output [3:0] regsel2, - input [31:0] iregs0, - input [31:0] iregs1, - input [31:0] iregs2 + output [3:0] read_0, + output [3:0] read_1, + output [3:0] read_2, + input [31:0] rdata_0, + input [31:0] rdata_1, + input [31:0] rdata_2 ); wire [31:0] regs0, regs1, regs2, rpc; - wire [31:0] op1_res, new_cps; + wire [31:0] op1_res, cpsr; /* shifter stuff */ wire [31:0] shift_oper; wire [31:0] shift_res; wire shift_cflag_out; - assign regs0 = (regsel0 == 4'b1111) ? rpc : iregs0; - assign regs1 = (regsel1 == 4'b1111) ? rpc : iregs1; - assign regs2 = iregs2; /* use regs2 for things that cannot be r15 */ + assign regs0 = (read_0 == 4'b1111) ? rpc : rdata_0; + assign regs1 = (read_1 == 4'b1111) ? rpc : rdata_1; + assign regs2 = rdata_2; /* use regs2 for things that cannot be r15 */ - IHATEARMSHIFT blowme(.insn(ansn), + IHATEARMSHIFT blowme(.insn(insn), .operand(regs1), .reg_amt(regs2), - .cflag_in(cps_in[`CPSR_C]), + .cflag_in(incpsr[`CPSR_C]), .res(shift_res), .cflag_out(shift_cflag_out)); - - always @ (*) begin - casez (ansn) - 32'b????000000??????????????1001????: begin /* Multiply */ + + always @(*) + casez (insn) + 32'b????000000??????????????1001????, /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ +// 32'b????00001???????????????1001????, /* Multiply long */ + 32'b????00010?001111????000000000000, /* MRS (Transfer PSR to register) */ + 32'b????00010?101001111100000000????, /* MSR (Transfer register to PSR) */ + 32'b????00?10?1010001111????????????, /* MSR (Transfer register or immediate to PSR, flag bits only) */ + 32'b????00010?00????????00001001????, /* Atomic swap */ + 32'b????000100101111111111110001????, /* Branch and exchange */ + 32'b????000??0??????????00001??1????, /* Halfword transfer - register offset */ + 32'b????000??1??????????00001??1????, /* Halfword transfer - register offset */ + 32'b????011????????????????????1????, /* Undefined. I hate ARM */ + 32'b????01??????????????????????????, /* Single data transfer */ + 32'b????100?????????????????????????, /* Block data transfer */ + 32'b????101?????????????????????????, /* Branch */ + 32'b????110?????????????????????????, /* Coprocessor data transfer */ + 32'b????1110???????????????????0????, /* Coprocessor data op */ + 32'b????1110???????????????????1????, /* Coprocessor register transfer */ + 32'b????1111????????????????????????: /* SWI */ rpc = inpc - 8; - regsel0 = ansn[15:12]; /* Rn */ - regsel1 = ansn[3:0]; /* Rm */ - regsel2 = ansn[11:8]; /* Rs */ - op1_res = regs1; - new_cps = cps_in; + 32'b????00??????????????????????????: /* ALU */ + rpc = inpc - (insn[25] ? 8 : (insn[4] ? 12 : 8)); + default: /* X everything else out */ + rpc = 32'hxxxxxxxx; + endcase + + always @(*) begin + read_0 = 4'hx; + read_1 = 4'hx; + read_2 = 4'hx; + + casez (insn) + 32'b????000000??????????????1001????: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + begin + read_0 = insn[15:12]; /* Rn */ + read_1 = insn[3:0]; /* Rm */ + read_2 = insn[11:8]; /* Rs */ + end +// 32'b????00001???????????????1001????, /* Multiply long */ +// read_0 = insn[11:8]; /* Rn */ +// read_1 = insn[3:0]; /* Rm */ +// read_2 = 4'b0; /* anyus */ + 32'b????00010?001111????000000000000, /* MRS (Transfer PSR to register) */ + 32'b????00010?101001111100000000????, /* MSR (Transfer register to PSR) */ + 32'b????00?10?1010001111????????????: /* MSR (Transfer register or immediate to PSR, flag bits only) */ + begin end /* Everything stays x'ed out. */ + 32'b????00??????????????????????????: /* ALU */ + begin + read_0 = insn[19:16]; /* Rn */ + read_1 = insn[3:0]; /* Rm */ + read_2 = insn[11:8]; /* Rs for shift */ + end + 32'b????00010?00????????00001001????: /* Atomic swap */ + begin + read_0 = insn[19:16]; /* Rn */ + read_1 = insn[3:0]; /* Rm */ end -/* - 32'b????00001???????????????1001????: begin * Multiply long * - regsel0 = ansn[11:8]; * Rn * - regsel1 = ansn[3:0]; * Rm * - regsel2 = 4'b0; * anyus * + 32'b????000100101111111111110001????: /* Branch and exchange */ + read_0 = insn[3:0]; /* Rn */ + 32'b????000??0??????????00001??1????: /* Halfword transfer - register offset */ + begin + read_0 = insn[19:16]; + read_1 = insn[3:0]; + end + 32'b????000??1??????????00001??1????: /* Halfword transfer - immediate offset */ + begin + read_0 = insn[19:16]; + read_1 = insn[3:0]; + end + 32'b????011????????????????????1????: /* Undefined. I hate ARM */ + begin end + 32'b????01??????????????????????????: /* Single data transfer */ + begin + read_0 = insn[19:16]; /* Rn */ + read_1 = insn[3:0]; /* Rm */ + end + 32'b????100?????????????????????????: /* Block data transfer */ + read_0 = insn[19:16]; + 32'b????101?????????????????????????: /* Branch */ + begin end + 32'b????110?????????????????????????: /* Coprocessor data transfer */ + read_0 = insn[19:16]; + 32'b????1110???????????????????0????, /* Coprocessor data op */ + 32'b????1110???????????????????1????, /* Coprocessor register transfer */ + 32'b????1111????????????????????????: /* SWI */ + begin end + default: + $display("Undecoded instruction"); + endcase + end + + always @(*) begin + op1_res = 32'hxxxxxxxx; + cpsr = 32'hxxxxxxxx; + casez (insn) + 32'b????000000??????????????1001????: begin /* Multiply */ op1_res = regs1; + cpsr = incpsr; end -*/ +// 32'b????00001???????????????1001????: begin /* Multiply long */ +// op1_res = regs1; +// end 32'b????00010?001111????000000000000: begin /* MRS (Transfer PSR to register) */ - rpc = inpc - 8; - new_cps = cps_in; + cpsr = incpsr; end 32'b????00010?101001111100000000????: begin /* MSR (Transfer register to PSR) */ - rpc = inpc - 8; - new_cps = cps_in; + cpsr = incpsr; end 32'b????00?10?1010001111????????????: begin /* MSR (Transfer register or immediate to PSR, flag bits onry) */ - rpc = inpc - 8; - new_cps = cps_in; + cpsr = incpsr; end 32'b????00??????????????????????????: begin /* ALU */ - rpc = inpc - (ansn[25] ? 8 : (ansn[4] ? 12 : 8)); - regsel0 = ansn[19:16]; /* Rn */ - regsel1 = ansn[3:0]; /* Rm */ - regsel2 = ansn[11:8]; /* Rs for shift */ - if(ansn[25]) begin /* the constant case */ - new_cps = cps_in; - op1_res = ({24'b0, ansn[7:0]} >> {ansn[11:8], 1'b0}) | ({24'b0, ansn[7:0]} << (5'b0 - {ansn[11:8], 1'b0})); + if(insn[25]) begin /* the constant case */ + cpsr = incpsr; + op1_res = ({24'b0, insn[7:0]} >> {insn[11:8], 1'b0}) | ({24'b0, insn[7:0]} << (5'b0 - {insn[11:8], 1'b0})); end else begin - new_cps = {cps_in[31:30], shift_cflag_out, cps_in[28:0]}; + cpsr = {incpsr[31:30], shift_cflag_out, incpsr[28:0]}; op1_res = shift_res; end end 32'b????00010?00????????00001001????: begin /* Atomic swap */ - rpc = inpc - 8; - regsel0 = ansn[19:16]; /* Rn */ - regsel1 = ansn[3:0]; /* Rm */ - regsel2 = 4'b0; /* anyus */ op1_res = regs1; end 32'b????000100101111111111110001????: begin /* Branch and exchange */ - rpc = inpc - 8; - regsel0 = ansn[3:0]; /* Rn */ - new_cps = cps_in; + cpsr = incpsr; end 32'b????000??0??????????00001??1????: begin /* Halfword transfer - register offset */ - rpc = inpc - 8; - regsel0 = ansn[19:16]; - regsel1 = ansn[3:0]; - regsel2 = 4'b0; op1_res = regs1; - new_cps = cps_in; + cpsr = incpsr; end 32'b????000??1??????????00001??1????: begin /* Halfword transfer - immediate offset */ - rpc = inpc - 8; - regsel0 = ansn[19:16]; - regsel1 = ansn[3:0]; - op1_res = {24'b0, ansn[11:8], ansn[3:0]}; - new_cps = cps_in; + op1_res = {24'b0, insn[11:8], insn[3:0]}; + cpsr = incpsr; end 32'b????011????????????????????1????: begin /* Undefined. I hate ARM */ /* eat shit */ end 32'b????01??????????????????????????: begin /* Single data transfer */ - rpc = inpc - 8; - regsel0 = ansn[19:16]; /* Rn */ - regsel1 = ansn[3:0]; /* Rm */ - if(ansn[25]) begin - op1_res = {20'b0, ansn[11:0]}; - new_cps = cps_in; + if(insn[25]) begin + op1_res = {20'b0, insn[11:0]}; + cpsr = incpsr; end else begin op1_res = shift_res; - new_cps = {cps_in[31:30], shift_cflag_out, cps_in[28:0]}; + cpsr = {incpsr[31:30], shift_cflag_out, incpsr[28:0]}; end end 32'b????100?????????????????????????: begin /* Block data transfer */ - rpc = inpc - 8; - regsel0 = ansn[19:16]; - op1_res = {16'b0, ansn[15:0]}; - new_cps = cps_in; + op1_res = {16'b0, insn[15:0]}; + cpsr = incpsr; end 32'b????101?????????????????????????: begin /* Branch */ - rpc = inpc - 8; - op1_res = {{6{ansn[23]}}, ansn[23:0], 2'b0}; - new_cps = cps_in; + op1_res = {{6{insn[23]}}, insn[23:0], 2'b0}; + cpsr = incpsr; end 32'b????110?????????????????????????: begin /* Coprocessor data transfer */ - rpc = inpc - 8; - regsel0 = ansn[19:16]; - op1_res = {24'b0, ansn[7:0]}; - new_cps = cps_in; + op1_res = {24'b0, insn[7:0]}; + cpsr = incpsr; end 32'b????1110???????????????????0????: begin /* Coprocessor data op */ - rpc = inpc - 8; - new_cps = cps_in; + cpsr = incpsr; end 32'b????1110???????????????????1????: begin /* Coprocessor register transfer */ - rpc = inpc - 8; - new_cps = cps_in; + cpsr = incpsr; end 32'b????1111????????????????????????: begin /* SWI */ - rpc = inpc - 8; - new_cps = cps_in; + cpsr = incpsr; end default: begin end endcase @@ -159,7 +212,7 @@ module Decode( op0 <= regs0; /* Rn - always */ op1 <= op1_res; /* 'operand 2' - Rm */ op2 <= regs2; /* thirdedge - Rs */ - cps_out <= new_cps; + outcpsr <= cpsr; end endmodule @@ -177,7 +230,7 @@ module IHATEARMSHIFT( /* might want to write our own damn shifter that does arithmetic/logical efficiently and stuff */ - always @ (*) begin + always @(*) if(insn[4]) begin shift_amt = {|reg_amt[7:5], reg_amt[4:0]}; elanus = 1'b1; @@ -185,7 +238,8 @@ module IHATEARMSHIFT( shift_amt = {insn[11:7] == 5'b0, insn[11:7]}; elanus = 1'b0; end - + + always @(*) case (insn[6:5]) /* shift type */ `SHIFT_LSL: begin {cflag_out, res} = {cflag_in, operand} << {elanus & shift_amt[5], shift_amt[4:0]}; @@ -209,5 +263,4 @@ module IHATEARMSHIFT( end end endcase - end endmodule