DCache: I/O rename
[firearm.git] / Execute.v
index ac759bb..4420a75 100644 (file)
--- a/Execute.v
+++ b/Execute.v
@@ -2,24 +2,32 @@ module Execute(
        input clk,
        input Nrst,     /* XXX not used yet */
        
-       input stall,
-       input flush,
+       input stall_2a,
+       input flush_2a,
        
-       input inbubble,
-       input [31:0] pc,
-       input [31:0] insn,
-       input [31:0] cpsr,
-       input [31:0] op0,
-       input [31:0] op1,
-       input [31:0] op2,
-       input carry,
+       input bubble_2a,
+       input [31:0] pc_2a,
+       input [31:0] insn_2a,
+       input [31:0] cpsr_2a,
+       input [31:0] spsr_2a,
+       input [31:0] op0_2a,
+       input [31:0] op1_2a,
+       input [31:0] op2_2a,
+       input carry_2a,
        
-       output reg outstall = 0,
-       output reg outbubble = 1,
-       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 outstall_2a = 0,
+       output reg bubble_3a = 1,
+       output reg [31:0] cpsr_3a = 0,
+       output reg [31:0] spsr_3a = 0,
+       output reg cpsrup_3a = 0,
+       output reg write_reg_3a = 1'bx,
+       output reg [3:0] write_num_3a = 4'bxxxx,
+       output reg [31:0] write_data_3a = 32'hxxxxxxxx,
+       output reg [31:0] jmppc_2a,
+       output reg jmp_2a,
+       output reg [31:0] pc_3a,
+       output reg [31:0] insn_3a,
+       output reg [31:0] op0_3a, op1_3a, op2_3a
        );
        
        reg mult_start;
@@ -27,18 +35,20 @@ module Execute(
        wire mult_done;
        wire [31:0] mult_result;
        
-       reg [31:0] alu_in0, alu_in1;
-       reg [3:0] alu_op;
-       reg alu_setflags;
-       wire [31:0] alu_result, alu_outcpsr;
-       wire alu_setres;
+       reg [31:0] alu_in0_2a, alu_in1_2a;
+       reg [3:0] alu_op_2a;
+       reg alu_setflags_2a;
+       wire [31:0] alu_result_2a, alu_outcpsr_2a;
+       wire alu_setres_2a;
        
-       reg next_outbubble;
-       reg [31:0] next_outcpsr;
-       reg next_write_reg;
-       reg [3:0] next_write_num;
-       reg [31:0] next_write_data;
+       reg next_bubble_3a;
+       reg [31:0] next_cpsr_3a, next_spsr_3a;
+       reg next_cpsrup_3a;
        
+       reg next_write_reg_3a;
+       reg [3:0] next_write_num_3a;
+       reg [31:0] next_write_data_3a;
+
        Multiplier multiplier(
                .clk(clk), .Nrst(Nrst),
                .start(mult_start), .acc0(mult_acc0), .in0(mult_in0),
@@ -46,42 +56,104 @@ module Execute(
        
        ALU alu(
                .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), .setres(alu_setres));
-       
+               .in0(alu_in0_2a), .in1(alu_in1_2a), .cpsr(cpsr_2a), .op(alu_op_2a),
+               .setflags(alu_setflags_2a), .shifter_carry(carry_2a),
+               .result(alu_result_2a), .cpsr_out(alu_outcpsr_2a), .setres(alu_setres_2a));
+
        always @(posedge clk)
        begin
-               if (!stall)
+               if (!stall_2a)
                begin
-                       outbubble <= next_outbubble;
-                       outcpsr <= next_outcpsr;
-                       write_reg <= next_write_reg;
-                       write_num <= next_write_num;
-                       write_data <= next_write_data;
+                       bubble_3a <= next_bubble_3a;
+                       cpsr_3a <= next_cpsr_3a;
+                       spsr_3a <= next_spsr_3a;
+                       cpsrup_3a <= next_cpsrup_3a;
+                       write_reg_3a <= next_write_reg_3a;
+                       write_num_3a <= next_write_num_3a;
+                       write_data_3a <= next_write_data_3a;
+                       pc_3a <= pc_2a;
+                       insn_3a <= insn_2a;
+                       op0_3a <= op0_2a;
+                       op1_3a <= op1_2a;
+                       op2_3a <= op2_2a;
                end
        end
+       
+       reg delayedflush_2a = 0;
+       always @(posedge clk)
+               if (flush_2a && outstall_2a /* halp! I can't do it now, maybe later? */)
+                       delayedflush_2a <= 1;
+               else if (!outstall_2a /* anything has been handled this time around */)
+                       delayedflush_2a <= 0;
 
+       reg outstall_3a = 0;
+       always @(posedge clk)
+               outstall_3a <= outstall_2a;
+       
        always @(*)
        begin
-               outstall = stall;
-               next_outbubble = inbubble;
-               next_outcpsr = cpsr;
-               next_write_reg = 0;
-               next_write_num = 4'hx;
-               next_write_data = 32'hxxxxxxxx;
+               outstall_2a = stall_2a;
+               
+               casez (insn_2a)
+               `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+                       outstall_2a = outstall_2a | ((!outstall_3a | !mult_done) && !bubble_2a);
+               endcase
+       end
+       
+       /* ALU inputs */
+       always @(*)
+       begin
+               alu_in0_2a = op0_2a;
+               alu_in1_2a = op1_2a;
+               alu_op_2a = insn_2a[24:21];
+               alu_setflags_2a = insn_2a[20] /* S */;
+       end
        
-               alu_in0 = 32'hxxxxxxxx;
-               alu_in1 = 32'hxxxxxxxx;
-               alu_op = 4'hx;  /* hax! */
-               alu_setflags = 1'bx;
+       /* Register outputs */
+       always @(*)
+       begin
+               next_cpsr_3a = cpsr_2a;
+               next_spsr_3a = spsr_2a;
+               next_cpsrup_3a = 0;
+               next_write_reg_3a = 0;
+               next_write_num_3a = 4'hx;
+               next_write_data_3a = 32'hxxxxxxxx;
                
-               casez (insn)
-               `DECODE_ALU_MULT,       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
-//             `DECODE_ALU_MUL_LONG,   /* Multiply long */
-               `DECODE_ALU_MRS,        /* MRS (Transfer PSR to register) */
+               casez(insn_2a)
+               `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+               begin
+                       next_cpsr_3a = insn_2a[20] /* S */ ? {mult_result[31] /* N */, mult_result == 0 /* Z */, 1'b0 /* C */, cpsr_2a[28] /* V */, cpsr_2a[27:0]} : cpsr_2a;
+                       next_cpsrup_3a = insn_2a[20] /* S */;
+                       next_write_reg_3a = 1;
+                       next_write_num_3a = insn_2a[19:16] /* Rd -- why the fuck isn't this the same place as ALU */;
+                       next_write_data_3a = mult_result;
+               end
+               `DECODE_ALU_MRS:        /* MRS (Transfer PSR to register) */
+               begin
+                       next_write_reg_3a = 1;
+                       next_write_num_3a = insn_2a[15:12];
+                       if (insn_2a[22] /* Ps */)
+                               next_write_data_3a = spsr_2a;
+                       else
+                               next_write_data_3a = cpsr_2a;
+               end
                `DECODE_ALU_MSR,        /* MSR (Transfer register to PSR) */
-               `DECODE_ALU_MSR_FLAGS,  /* MSR (Transfer register or immediate to PSR, flag bits only) */
+               `DECODE_ALU_MSR_FLAGS:  /* MSR (Transfer register or immediate to PSR, flag bits only) */
+               begin
+                       if ((cpsr_2a[4:0] == `MODE_USR) || (insn_2a[16] /* that random bit */ == 1'b0)) /* flags only */
+                       begin
+                               if (insn_2a[22] /* Ps */)
+                                       next_spsr_3a = {op0_2a[31:29], spsr_2a[28:0]};
+                               else
+                                       next_cpsr_3a = {op0_2a[31:29], cpsr_2a[28:0]};
+                       end else begin
+                               if (insn_2a[22] /* Ps */)
+                                       next_spsr_3a = op0_2a;
+                               else
+                                       next_cpsr_3a = op0_2a;
+                       end
+                       next_cpsrup_3a = 1;
+               end
                `DECODE_ALU_SWP,        /* Atomic swap */
                `DECODE_ALU_BX,         /* Branch */
                `DECODE_ALU_HDATA_REG,  /* Halfword transfer - register offset */
@@ -89,23 +161,85 @@ module Execute(
                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;
+                       if (alu_setres_2a) begin
+                               next_write_reg_3a = 1;
+                               next_write_num_3a = insn_2a[15:12] /* Rd */;
+                               next_write_data_3a = alu_result_2a;
                        end
                        
-                       next_outcpsr = alu_outcpsr;
+                       if (insn_2a[20] /* S */) begin
+                               next_cpsrup_3a = 1;
+                               next_cpsr_3a = ((insn_2a[15:12] == 4'b1111) && insn_2a[20]) ? spsr_2a : alu_outcpsr_2a;
+                       end
                end
                `DECODE_LDRSTR_UNDEFINED,       /* Undefined. I hate ARM */
                `DECODE_LDRSTR,         /* Single data transfer */
-               `DECODE_LDMSTM,         /* Block data transfer */
-               `DECODE_BRANCH,         /* Branch */
+               `DECODE_LDMSTM:         /* Block data transfer */
+               begin end
+               `DECODE_BRANCH:         /* Branch */
+               begin
+                       if(insn_2a[24] /* L */) begin
+                               next_write_reg_3a = 1;
+                               next_write_num_3a = 4'hE; /* link register */
+                               next_write_data_3a = pc_2a + 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_2a)
+               `DECODE_ALU_MULT:
+               begin
+                       if (!outstall_3a /* i.e., this is a new one */ && !bubble_2a /* i.e., this is a real one */)
+                       begin
+                               mult_start = 1;
+                               mult_acc0 = insn_2a[21] /* A */ ? op0_2a /* Rn */ : 32'h0;
+                               mult_in0 = op1_2a /* Rm */;
+                               mult_in1 = op2_2a /* Rs */;
+                               $display("New MUL instruction");
+                       end
+               end
+               endcase
+       end
+
+       /* Miscellaneous cleanup. */
+       always @(*)
+       begin
+               next_bubble_3a = bubble_2a | flush_2a | delayedflush_2a;
+
+               jmp_2a = 1'b0;
+               jmppc_2a = 32'h00000000;
+
+               casez (insn_2a)
+               `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+                       next_bubble_3a = next_bubble_3a | !mult_done | !outstall_3a;
+               `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(!bubble_2a && !flush_2a && !delayedflush_2a && !outstall_2a /* Let someone else take precedence. */) begin
+                               jmppc_2a = pc_2a + op0_2a + 32'h8;
+                               jmp_2a = 1'b1;
+                       end
+               end                     /* Branch */
                `DECODE_LDCSTC,         /* Coprocessor data transfer */
                `DECODE_CDP,            /* Coprocessor data op */
                `DECODE_MRCMCR,         /* Coprocessor register transfer */
@@ -154,7 +288,6 @@ module Multiplier(
        end
 endmodule
 
-/* XXX is the interface correct? */
 module ALU(
        input clk,
        input Nrst,     /* XXX not used yet */
@@ -170,15 +303,18 @@ module ALU(
        output reg [31:0] cpsr_out,
        output reg setres
 );
-       wire [31:0] res;
-       wire flag_n, flag_z, flag_c, flag_v, setres;
+       reg [31:0] res;
+       reg flag_n, flag_z, flag_c, flag_v;
        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 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;
@@ -197,26 +333,36 @@ 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
                `ALU_ADD: begin
                        {flag_c, result} = sum;
+                       flag_v = sum_v;
                        setres = 1'b1;
                end
                `ALU_ADC: begin
                        {flag_c, result} = sum + {32'b0, cpsr[`CPSR_C]};
+                       flag_v = sum_v | (~sum[31] & result[31]);
                        setres = 1'b1;
                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
                `ALU_TST: begin
@@ -231,10 +377,13 @@ module ALU(
                end
                `ALU_CMP: begin
                        {flag_c, result} = diff;
+                       flag_c = !flag_c;
+                       flag_v = diff_v;
                        setres = 1'b0;
                end
                `ALU_CMN: begin
                        {flag_c, result} = sum;
+                       flag_v = sum_v;
                        setres = 1'b0;
                end
                `ALU_ORR: begin
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