X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/2393422aab14e1b2172b4e52b9117272cc13c72e..fb33d46774e2f2d95d54e7eb32754048624a63ca:/Execute.v?ds=inline diff --git a/Execute.v b/Execute.v index cd71d76..c1049ba 100644 --- a/Execute.v +++ b/Execute.v @@ -19,13 +19,15 @@ module Execute( output reg outbubble = 1, output reg [31:0] outcpsr = 0, output reg [31:0] outspsr = 0, + output reg outcpsrup = 0, output reg write_reg = 1'bx, output reg [3:0] write_num = 4'bxxxx, output reg [31:0] write_data = 32'hxxxxxxxx, output reg [31:0] jmppc, output reg jmp, output reg [31:0] outpc, - output reg [31:0] outinsn + output reg [31:0] outinsn, + output reg [31:0] outop0, outop1, outop2 ); reg mult_start; @@ -41,6 +43,7 @@ module Execute( reg next_outbubble; reg [31:0] next_outcpsr, next_outspsr; + reg next_outcpsrup; reg next_write_reg; reg [3:0] next_write_num; @@ -56,7 +59,7 @@ module Execute( .in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op), .setflags(alu_setflags), .shifter_carry(carry), .result(alu_result), .cpsr_out(alu_outcpsr), .setres(alu_setres)); - + always @(posedge clk) begin if (!stall) @@ -64,60 +67,67 @@ module Execute( outbubble <= next_outbubble; outcpsr <= next_outcpsr; outspsr <= next_outspsr; + outcpsrup <= next_outcpsrup; write_reg <= next_write_reg; write_num <= next_write_num; write_data <= next_write_data; outpc <= pc; outinsn <= insn; + outop0 <= op0; + outop1 <= op1; + outop2 <= op2; end end + + reg delayedflush = 0; + always @(posedge clk) + if (flush && outstall /* halp! I can't do it now, maybe later? */) + delayedflush <= 1; + else if (!outstall /* anything has been handled this time around */) + delayedflush <= 0; reg prevstall = 0; always @(posedge clk) prevstall <= outstall; - + always @(*) begin outstall = stall; - next_outbubble = inbubble | flush; + + casez (insn) + `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + outstall = outstall | ((!prevstall | !mult_done) && !inbubble); + endcase + end + + /* ALU inputs */ + always @(*) + begin + alu_in0 = op0; + alu_in1 = op1; + alu_op = insn[24:21]; + alu_setflags = insn[20] /* S */; + end + + /* Register outputs */ + always @(*) + begin next_outcpsr = cpsr; next_outspsr = spsr; + next_outcpsrup = 0; next_write_reg = 0; next_write_num = 4'hx; next_write_data = 32'hxxxxxxxx; - - mult_start = 0; - mult_acc0 = 32'hxxxxxxxx; - mult_in0 = 32'hxxxxxxxx; - mult_in1 = 32'hxxxxxxxx; - - alu_in0 = 32'hxxxxxxxx; - alu_in1 = 32'hxxxxxxxx; - alu_op = 4'hx; /* hax! */ - alu_setflags = 1'bx; - - jmp = 1'b0; - jmppc = 32'hxxxxxxxx; - - casez (insn) + + casez(insn) `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ begin - if (!prevstall && !inbubble) - begin - mult_start = 1; - mult_acc0 = insn[21] /* A */ ? op0 /* Rn */ : 32'h0; - mult_in0 = op1 /* Rm */; - mult_in1 = op2 /* Rs */; - $display("New MUL instruction"); - end - outstall = stall | ((!prevstall | !mult_done) && !inbubble); - next_outbubble = inbubble | !mult_done | !prevstall; next_outcpsr = insn[20] /* S */ ? {mult_result[31] /* N */, mult_result == 0 /* Z */, 1'b0 /* C */, cpsr[28] /* V */, cpsr[27:0]} : cpsr; + next_outcpsrup = insn[20] /* S */; next_write_reg = 1; next_write_num = insn[19:16] /* Rd -- why the fuck isn't this the same place as ALU */; next_write_data = mult_result; end -// `DECODE_ALU_MUL_LONG, /* Multiply long */ `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */ begin next_write_reg = 1; @@ -129,6 +139,7 @@ module Execute( end `DECODE_ALU_MSR, /* MSR (Transfer register to PSR) */ `DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */ + begin if ((cpsr[4:0] == `MODE_USR) || (insn[16] /* that random bit */ == 1'b0)) /* flags only */ begin if (insn[22] /* Ps */) @@ -141,6 +152,8 @@ module Execute( else next_outcpsr = op0; end + next_outcpsrup = 1; + end `DECODE_ALU_SWP, /* Atomic swap */ `DECODE_ALU_BX, /* Branch */ `DECODE_ALU_HDATA_REG, /* Halfword transfer - register offset */ @@ -148,32 +161,82 @@ module Execute( begin end `DECODE_ALU: /* ALU */ begin - alu_in0 = op0; - alu_in1 = op1; - alu_op = insn[24:21]; - alu_setflags = insn[20] /* S */; - if (alu_setres) begin next_write_reg = 1; next_write_num = insn[15:12] /* Rd */; next_write_data = alu_result; end - next_outcpsr = ((insn[15:12] == 4'b1111) && insn[20]) ? spsr : alu_outcpsr; + if (insn[20] /* S */) begin + next_outcpsrup = 1; + next_outcpsr = ((insn[15:12] == 4'b1111) && insn[20]) ? spsr : alu_outcpsr; + end end `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */ `DECODE_LDRSTR, /* Single data transfer */ `DECODE_LDMSTM: /* Block data transfer */ begin end + `DECODE_BRANCH: /* Branch */ + begin + if(insn[24] /* L */) begin + next_write_reg = 1; + next_write_num = 4'hE; /* link register */ + next_write_data = pc + 32'h4; + end + end + endcase + end + + /* Multiplier inputs */ + always @(*) + begin + mult_start = 0; + mult_acc0 = 32'hxxxxxxxx; + mult_in0 = 32'hxxxxxxxx; + mult_in1 = 32'hxxxxxxxx; + + casez(insn) + `DECODE_ALU_MULT: + begin + if (!prevstall /* i.e., this is a new one */ && !inbubble /* i.e., this is a real one */) + begin + mult_start = 1; + mult_acc0 = insn[21] /* A */ ? op0 /* Rn */ : 32'h0; + mult_in0 = op1 /* Rm */; + mult_in1 = op2 /* Rs */; + $display("New MUL instruction"); + end + end + endcase + end + + /* Miscellaneous cleanup. */ + always @(*) + begin + next_outbubble = inbubble | flush | delayedflush; + + jmp = 1'b0; + jmppc = 32'h00000000; + + casez (insn) + `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + next_outbubble = next_outbubble | !mult_done | !prevstall; + `DECODE_ALU_MRS, /* MRS (Transfer PSR to register) */ + `DECODE_ALU_MSR, /* MSR (Transfer register to PSR) */ + `DECODE_ALU_MSR_FLAGS, /* MSR (Transfer register or immediate to PSR, flag bits only) */ + `DECODE_ALU_SWP, /* Atomic swap */ + `DECODE_ALU_BX, /* Branch */ + `DECODE_ALU_HDATA_REG, /* Halfword transfer - register offset */ + `DECODE_ALU_HDATA_IMM, /* Halfword transfer - immediate offset */ + `DECODE_ALU, /* ALU */ + `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */ + `DECODE_LDRSTR, /* Single data transfer */ + `DECODE_LDMSTM: /* Block data transfer */ + begin end `DECODE_BRANCH: begin - if(!inbubble) begin + if(!inbubble && !flush && !delayedflush && !outstall /* Let someone else take precedence. */) begin jmppc = pc + op0 + 32'h8; - if(insn[24]) begin - next_write_reg = 1; - next_write_num = 4'hE; /* link register */ - next_write_data = pc - 32'h4; - end jmp = 1'b1; end end /* Branch */ @@ -247,7 +310,7 @@ module ALU( assign sum = {1'b0, in0} + {1'b0, in1}; assign diff = {1'b0, in0} - {1'b0, in1}; - assign rdiff = {1'b0, in1} + {1'b0, in0}; + assign rdiff = {1'b0, in1} - {1'b0, in0}; assign sum_v = (in0[31] ^~ in1[31]) & (sum[31] ^ in0[31]); assign diff_v = (in0[31] ^ in1[31]) & (diff[31] ^ in0[31]); assign rdiff_v = (in0[31] ^ in1[31]) & (rdiff[31] ^ in1[31]); @@ -270,11 +333,13 @@ module ALU( end `ALU_SUB: begin {flag_c, result} = diff; + flag_c = !flag_c; flag_v = diff_v; setres = 1'b1; end `ALU_RSB: begin {flag_c, result} = rdiff; + flag_c = !flag_c; flag_v = rdiff_v; setres = 1'b1; end @@ -290,11 +355,13 @@ module ALU( end `ALU_SBC: begin {flag_c, result} = diff - {32'b0, (~cpsr[`CPSR_C])}; + flag_c = !flag_c; flag_v = diff_v | (diff[31] & ~result[31]); setres = 1'b1; end `ALU_RSC: begin {flag_c, result} = rdiff - {32'b0, (~cpsr[`CPSR_C])}; + flag_c = !flag_c; flag_v = rdiff_v | (rdiff[31] & ~result[31]); setres = 1'b1; end @@ -310,6 +377,7 @@ module ALU( end `ALU_CMP: begin {flag_c, result} = diff; + flag_c = !flag_c; flag_v = diff_v; setres = 1'b0; end