really fix execute

[firearm.git] / Execute.v

diff --git a/Execute.v b/Execute.v
index b1e9df52c8a015d0d6df4734119f665a7e77784e..d93a7ee22465b64490ffb0b40b67e9566edcd198 100644 (file)
--- a/Execute.v
+++ b/Execute.v
@@ -19,7 +19,9 @@ module Execute(
        output reg [31:0] outcpsr = 0,
        output reg write_reg = 1'bx,
        output reg [3:0] write_num = 4'bxxxx,
        output reg [31:0] outcpsr = 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] write_data = 32'hxxxxxxxx,
+       output reg [31:0] outpc,
+       output reg outflush

        );
        
        reg mult_start;
        );
        
        reg mult_start;


@@ -27,10 +29,17 @@ module Execute(
        wire mult_done;
        wire [31:0] mult_result;
        
        wire mult_done;
        wire [31:0] mult_result;
        

-       wire [31:0] alu_in0, alu_in1;
-       wire [3:0] alu_op;
-       wire alu_setflags, alu_set;
+       reg [31:0] alu_in0, alu_in1;
+       reg [3:0] alu_op;
+       reg alu_setflags;

        wire [31:0] alu_result, alu_outcpsr;
        wire [31:0] alu_result, alu_outcpsr;

+       wire alu_setres;
+       
+       reg next_outbubble;
+       reg [31:0] next_outcpsr;
+       reg next_write_reg;
+       reg [3:0] next_write_num;
+       reg [31:0] next_write_data;

        
        Multiplier multiplier(
                .clk(clk), .Nrst(Nrst),
        
        Multiplier multiplier(
                .clk(clk), .Nrst(Nrst),


@@ -41,7 +50,107 @@ module Execute(
                .clk(clk), .Nrst(Nrst),
                .in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op),
                .setflags(alu_setflags), .shifter_carry(carry),
                .clk(clk), .Nrst(Nrst),
                .in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op),
                .setflags(alu_setflags), .shifter_carry(carry),

-               .result(alu_result), .cpsr_out(alu_outcpsr), .set(alu_set));
+               .result(alu_result), .cpsr_out(alu_outcpsr), .setres(alu_setres));
+       
+       always @(posedge clk)
+       begin
+               if (!stall)
+               begin
+                       outbubble <= next_outbubble;
+                       outcpsr <= next_outcpsr;
+                       write_reg <= next_write_reg;
+                       write_num <= next_write_num;
+                       write_data <= next_write_data;
+               end
+       end
+
+       reg prevstall = 0;
+       always @(posedge clk)
+               prevstall <= outstall;
+
+       always @(*)
+       begin
+               outstall = stall;
+               next_outbubble = inbubble;
+               next_outcpsr = cpsr;
+               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;
+               
+               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_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) */
+               `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 */
+               begin end
+               `DECODE_ALU:            /* ALU */
+               begin
+                       alu_in0 = op0;
+                       alu_in1 = op1;
+                       alu_op = insn[24:21];
+                       alu_setflags = insn[20] /* I */;
+                       
+                       if (alu_setres) begin
+                               next_write_reg = 1;
+                               next_write_num = insn[15:12] /* Rd */;
+                               next_write_data = alu_result;
+                       end
+                       
+                       next_outcpsr = alu_outcpsr;
+               end
+               `DECODE_LDRSTR_UNDEFINED,       /* Undefined. I hate ARM */
+               `DECODE_LDRSTR,         /* Single data transfer */
+               `DECODE_LDMSTM:         /* Block data transfer */
+               begin end
+               `DECODE_BRANCH:
+               begin
+                       outpc = pc + op0;
+                       if(insn[24]) begin
+                               next_write_reg = 1;
+                               next_write_num = 4'hE; /* link register */
+                               next_write_data = pc + 32'h4;
+                       end
+               end                     /* Branch */
+               `DECODE_LDCSTC,         /* Coprocessor data transfer */
+               `DECODE_CDP,            /* Coprocessor data op */
+               `DECODE_MRCMCR,         /* Coprocessor register transfer */
+               `DECODE_SWI:            /* SWI */
+               begin end
+               default:                /* X everything else out */
+               begin end
+               endcase
+       end

 endmodule
 
 module Multiplier(
 endmodule
 
 module Multiplier(


@@ -81,7 +190,6 @@ module Multiplier(
        end
 endmodule
 
        end
 endmodule
 

-/* XXX is the interface correct? */

 module ALU(
        input clk,
        input Nrst,     /* XXX not used yet */
 module ALU(
        input clk,
        input Nrst,     /* XXX not used yet */


@@ -95,17 +203,20 @@ module ALU(
 
        output reg [31:0] result,
        output reg [31:0] cpsr_out,
 
        output reg [31:0] result,
        output reg [31:0] cpsr_out,

-       output reg set
+       output reg setres

 );
        wire [31:0] res;
        wire flag_n, flag_z, flag_c, flag_v, setres;
        wire [32:0] sum, diff, rdiff;
 );
        wire [31:0] res;
        wire flag_n, flag_z, flag_c, flag_v, setres;
        wire [32:0] sum, diff, rdiff;

+       wire sum_v, diff_v, rdiff_v;

 
        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 sum = {1'b0, in0} + {1'b0, in1};
        assign diff = {1'b0, in0} - {1'b0, in1};
        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]);

 
 

-       /* TODO XXX flag_v not set correctly */

        always @(*) begin
                res = 32'hxxxxxxxx;
                setres = 1'bx;
        always @(*) begin
                res = 32'hxxxxxxxx;
                setres = 1'bx;


@@ -113,89 +224,90 @@ module ALU(
                flag_v = cpsr[`CPSR_V];
                case(op)
                `ALU_AND: begin
                flag_v = cpsr[`CPSR_V];
                case(op)
                `ALU_AND: begin

-                       res = in0 & in1;
+                       result = in0 & in1;

                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_EOR: begin
                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_EOR: begin

-                       res = in0 ^ in1;
+                       result = in0 ^ in1;

                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_SUB: begin
                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_SUB: begin

-                       {flag_c, res} = diff;
+                       {flag_c, result} = diff;
+                       flag_v = diff_v;

                        setres = 1'b1;
                end
                `ALU_RSB: begin
                        setres = 1'b1;
                end
                `ALU_RSB: begin

-                       {flag_c, res} = rdiff;
+                       {flag_c, result} = rdiff;
+                       flag_v = rdiff_v;

                        setres = 1'b1;
                end
                `ALU_ADD: begin
                        setres = 1'b1;
                end
                `ALU_ADD: begin

-                       {flag_c, res} = sum;
+                       {flag_c, result} = sum;
+                       flag_v = sum_v;

                        setres = 1'b1;
                end
                `ALU_ADC: begin
                        setres = 1'b1;
                end
                `ALU_ADC: begin

-                       {flag_c, res} = sum + {32'b0, cpsr[`CPSR_C]};
+                       {flag_c, result} = sum + {32'b0, cpsr[`CPSR_C]};
+                       flag_v = sum_v | (~sum[31] & result[31]);

                        setres = 1'b1;
                end
                `ALU_SBC: begin
                        setres = 1'b1;
                end
                `ALU_SBC: begin

-                       {flag_c, res} = diff - {32'b0, (~cpsr[`CPSR_C])};
+                       {flag_c, result} = diff - {32'b0, (~cpsr[`CPSR_C])};
+                       flag_v = diff_v | (diff[31] & ~result[31]);

                        setres = 1'b1;
                end
                `ALU_RSC: begin
                        setres = 1'b1;
                end
                `ALU_RSC: begin

-                       {flag_c, res} = rdiff - {32'b0, (~cpsr[`CPSR_C])};
+                       {flag_c, result} = rdiff - {32'b0, (~cpsr[`CPSR_C])};
+                       flag_v = rdiff_v | (rdiff[31] & ~result[31]);

                        setres = 1'b1;
                end
                `ALU_TST: begin
                        setres = 1'b1;
                end
                `ALU_TST: begin

-                       res = in0 & in1;
+                       result = in0 & in1;

                        flag_c = shifter_carry;
                        setres = 1'b0;
                end
                `ALU_TEQ: begin
                        flag_c = shifter_carry;
                        setres = 1'b0;
                end
                `ALU_TEQ: begin

-                       res = in0 ^ in1;
+                       result = in0 ^ in1;

                        flag_c = shifter_carry;
                        setres = 1'b0;
                end
                `ALU_CMP: begin
                        flag_c = shifter_carry;
                        setres = 1'b0;
                end
                `ALU_CMP: begin

-                       {flag_c, res} = diff;
+                       {flag_c, result} = diff;
+                       flag_v = diff_v;

                        setres = 1'b0;
                end
                `ALU_CMN: begin
                        setres = 1'b0;
                end
                `ALU_CMN: begin

-                       {flag_c, res} = sum;
+                       {flag_c, result} = sum;
+                       flag_v = sum_v;

                        setres = 1'b0;
                end
                `ALU_ORR: begin
                        setres = 1'b0;
                end
                `ALU_ORR: begin

-                       res = in0 | in1;
+                       result = in0 | in1;

                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_MOV: begin
                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_MOV: begin

-                       res = in1;
+                       result = in1;

                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_BIC: begin
                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_BIC: begin

-                       res = in0 & (~in1);
+                       result = in0 & (~in1);

                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_MVN: begin
                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                `ALU_MVN: begin

-                       res = ~in1;
+                       result = ~in1;

                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                endcase
                        flag_c = shifter_carry;
                        setres = 1'b1;
                end
                endcase

+               
+               flag_z = (result == 0);
+               flag_n = result[31];
+               
+               cpsr_out = setflags ? {flag_n, flag_z, flag_c, flag_v, cpsr[27:0]} : cpsr;

        end
        end

-
-       always @(*) begin
-               flag_z = (res == 0);
-               flag_n = res[31];
-       end
-
-       always @(posedge clk) begin
-               result <= res;
-               cpsr_out <= setflags ? {flag_n, flag_z, flag_c, flag_v, cpsr[27:0]} : cpsr;
-               set <= setres;
-       end
-

 endmodule
 endmodule