X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/d0e6b3ca86dc90cd78057c0df333d880985d6684..6d18bf2758e61202ba514a431bbcfca827dd7d1e:/Execute.v?ds=inline diff --git a/Execute.v b/Execute.v index 38a192f..ac446aa 100644 --- a/Execute.v +++ b/Execute.v @@ -19,6 +19,7 @@ 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, @@ -42,6 +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; @@ -57,7 +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) @@ -65,6 +67,7 @@ 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; @@ -75,6 +78,13 @@ module Execute( 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) @@ -83,9 +93,10 @@ module Execute( always @(*) begin outstall = stall; - next_outbubble = inbubble | flush; + next_outbubble = inbubble | flush | delayedflush; next_outcpsr = cpsr; next_outspsr = spsr; + next_outcpsrup = 0; next_write_reg = 0; next_write_num = 4'hx; next_write_data = 32'hxxxxxxxx; @@ -114,9 +125,10 @@ module Execute( mult_in1 = op2 /* Rs */; $display("New MUL instruction"); end - outstall = stall | ((!prevstall | !mult_done) && !inbubble); - next_outbubble = inbubble | !mult_done | !prevstall; + outstall = outstall | ((!prevstall | !mult_done) && !inbubble); + next_outbubble = next_outbubble | !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; @@ -130,9 +142,11 @@ module Execute( next_write_data = spsr; else next_write_data = cpsr; + next_outcpsrup = 1; 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 */) @@ -145,6 +159,8 @@ 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 */ @@ -164,6 +180,7 @@ module Execute( end next_outcpsr = ((insn[15:12] == 4'b1111) && insn[20]) ? spsr : alu_outcpsr; + next_outcpsrup = insn[20] /* S */; end `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */ `DECODE_LDRSTR, /* Single data transfer */ @@ -171,12 +188,12 @@ module Execute( 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; + next_write_data = pc + 32'h4; end jmp = 1'b1; end @@ -251,7 +268,7 @@ 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]); @@ -274,11 +291,13 @@ 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 @@ -294,11 +313,13 @@ 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 @@ -314,6 +335,7 @@ module ALU( end `ALU_CMP: begin {flag_c, result} = diff; + flag_c = !flag_c; flag_v = diff_v; setres = 1'b0; end