Decode: Fix conditional for immediate mode.
[firearm.git] / Decode.v
index d817d13..2c22746 100644 (file)
--- a/Decode.v
+++ b/Decode.v
@@ -2,13 +2,17 @@
 
 module Decode(
        input clk,
+       input stall,
        input [31:0] insn,
        input [31:0] inpc,
        input [31:0] incpsr,
+       input [31:0] inspsr,
        output reg [31:0] op0,
        output reg [31:0] op1,
        output reg [31:0] op2,
        output reg carry,
+       output reg [31:0] outcpsr,
+       output reg [31:0] outspsr,
 
        output reg [3:0] read_0,
        output reg [3:0] read_1,
@@ -33,12 +37,12 @@ module Decode(
        assign regs1 = (read_1 == 4'b1111) ? rpc : rdata_1;
        assign regs2 = rdata_2; /* use regs2 for things that cannot be r15 */
 
-       IREALLYHATEARMSHIFT blowme(.insn(insn),
-                                  .operand(regs1),
-                                  .reg_amt(regs2),
-                                  .cflag_in(incpsr[`CPSR_C]),
-                                  .res(shift_res),
-                                  .cflag_out(shift_cflag_out));
+       IREALLYHATEARMSHIFT shift(.insn(insn),
+                                 .operand(regs1),
+                                 .reg_amt(regs2),
+                                 .cflag_in(incpsr[`CPSR_C]),
+                                 .res(shift_res),
+                                 .cflag_out(shift_cflag_out));
 
        SuckLessRotator whirr(.oper({24'b0, insn[7:0]}),
                              .amt(insn[11:8]),
@@ -61,124 +65,102 @@ module Decode(
                `DECODE_BRANCH,                 /* Branch */
                `DECODE_LDCSTC,                 /* Coprocessor data transfer */
                `DECODE_CDP,                    /* Coprocessor data op */
-               `DECODE_MRCMCR,                 /* Coprocessor register transfer */
                `DECODE_SWI:                    /* SWI */
-                       rpc = inpc - 8;
+                       rpc = inpc + 8;
+               `DECODE_MRCMCR:                 /* Coprocessor register transfer */
+                       rpc = inpc + 12;
                `DECODE_ALU:                    /* ALU */
-                       rpc = inpc - (insn[25] ? 8 : (insn[4] ? 12 : 8));
+                       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;
                
+               op0_out = 32'hxxxxxxxx;
+               op1_out = 32'hxxxxxxxx;
+               op2_out = 32'hxxxxxxxx;
+               carry_out = 1'bx;
+               
                casez (insn)
                `DECODE_ALU_MULT:       /* 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 */
+                       
+                       op0_out = regs0;
+                       op1_out = regs1;
+                       op2_out = regs2;
                end
 //             `DECODE_ALU_MUL_LONG:   /* Multiply long */
+//             begin
 //                     read_0 = insn[11:8]; /* Rn */
 //                     read_1 = insn[3:0];   /* Rm */
 //                     read_2 = 4'b0;       /* anyus */
+//
+//                     op1_res = regs1;
+//             end
                `DECODE_ALU_MRS:        /* MRS (Transfer PSR to register) */
                begin end
-               `DECODE_ALU_MSR,        /* MSR (Transfer register to PSR) */
+               `DECODE_ALU_MSR:        /* MSR (Transfer register to PSR) */
+               begin
+                       read_0 = insn[3:0];     /* Rm */
+                       
+                       op0_out = regs0;
+               end
                `DECODE_ALU_MSR_FLAGS:  /* MSR (Transfer register or immediate to PSR, flag bits only) */
+               begin
                        read_0 = insn[3:0];     /* Rm */
+                       
+                       if(insn[25]) begin     /* the constant case */
+                               op0_out = rotate_res;
+                       end else begin
+                               op0_out = regs0;
+                       end
+               end
                `DECODE_ALU_SWP:        /* Atomic swap */
                begin
                        read_0 = insn[19:16]; /* Rn */
                        read_1 = insn[3:0];   /* Rm */
+                       
+                       op0_out = regs0;
+                       op1_out = regs1;
                end
                `DECODE_ALU_BX:         /* Branch and exchange */
+               begin
                        read_0 = insn[3:0];   /* Rn */
+                       
+                       op0_out = regs0;
+               end
                `DECODE_ALU_HDATA_REG:  /* Halfword transfer - register offset */
                begin
                        read_0 = insn[19:16];
                        read_1 = insn[3:0];
+                       read_2 = insn[15:12];
+
+                       op0_out = regs0;
+                       op1_out = regs1;
+                       op2_out = regs2;
                end
                `DECODE_ALU_HDATA_IMM:  /* Halfword transfer - immediate offset */
                begin
                        read_0 = insn[19:16];
+                       read_1 = insn[15:12];
+                       
+                       op0_out = regs0;
+                       op1_out = {24'b0, insn[11:8], insn[3:0]};
+                       op2_out = regs1;
                end
                `DECODE_ALU:            /* ALU */
                begin
                        read_0 = insn[19:16]; /* Rn */
                        read_1 = insn[3:0];   /* Rm */
                        read_2 = insn[11:8];  /* Rs for shift */
-               end
-               `DECODE_LDRSTR_UNDEFINED:       /* Undefined. I hate ARM */
-               begin end
-               `DECODE_LDRSTR:         /* Single data transfer */
-               begin
-                       read_0 = insn[19:16]; /* Rn */
-                       read_1 = insn[3:0];   /* Rm */
-               end
-               `DECODE_LDMSTM:         /* Block data transfer */
-                       read_0 = insn[19:16];
-               `DECODE_BRANCH:         /* Branch */
-               begin end
-               `DECODE_LDCSTC:         /* Coprocessor data transfer */
-                       read_0 = insn[19:16];
-               `DECODE_CDP:            /* Coprocessor data op */
-               begin end
-               `DECODE_MRCMCR:         /* Coprocessor register transfer */
-                       read_0 = insn[15:12];
-               `DECODE_SWI:            /* SWI */
-               begin end
-               default:
-                       $display("Undecoded instruction");
-               endcase
-       end
-       
-       always @(*) begin
-               op0_out = 32'hxxxxxxxx;
-               op1_out = 32'hxxxxxxxx;
-               op2_out = 32'hxxxxxxxx;
-               carry_out = 1'bx;
-               casez (insn)
-               `DECODE_ALU_MULT: begin         /* Multiply */
-                       op0_out = regs0;
-                       op1_out = regs1;
-                       op2_out = regs2;
-               end
-//             `DECODE_ALU_MULT_LONG: begin    /* Multiply long */
-//                     op1_res = regs1;
-//             end
-               `DECODE_ALU_MRS: begin          /* MRS (Transfer PSR to register) */
-               end
-               `DECODE_ALU_MSR: begin          /* MSR (Transfer register to PSR) */
-                       op0_out = regs0;
-               end
-                `DECODE_ALU_MSR_FLAGS: begin   /* MSR (Transfer register or immediate to PSR, flag bits only) */
-                       if(insn[25]) begin     /* the constant case */
-                               op0_out = rotate_res;
-                       end else begin
-                               op0_out = regs0;
-                       end
-                end
-               `DECODE_ALU_SWP: begin          /* Atomic swap */
-                       op0_out = regs0;
-                       op1_out = regs1;
-               end
-               `DECODE_ALU_BX: begin           /* Branch and exchange */
-                       op0_out = regs0;
-               end
-               `DECODE_ALU_HDATA_REG: begin    /* Halfword transfer - register offset */
-                       op0_out = regs0;
-                       op1_out = regs1;
-               end
-               `DECODE_ALU_HDATA_IMM: begin    /* Halfword transfer - immediate offset */
-                       op0_out = regs0;
-                       op1_out = {24'b0, insn[11:8], insn[3:0]};
-               end
-               `DECODE_ALU: begin              /* ALU */
+                       
                        op0_out = regs0;
                        if(insn[25]) begin     /* the constant case */
                                carry_out = incpsr[`CPSR_C];
@@ -188,46 +170,72 @@ module Decode(
                                op1_out = shift_res;
                        end
                end
-               `DECODE_LDRSTR_UNDEFINED: begin /* Undefined. I hate ARM */
+               `DECODE_LDRSTR_UNDEFINED:       /* Undefined. I hate ARM */
+               begin
                        /* eat shit */
                end
-               `DECODE_LDRSTR: begin           /* Single data transfer */
+               `DECODE_LDRSTR:         /* Single data transfer */
+               begin
+                       read_0 = insn[19:16]; /* Rn */
+                       read_1 = insn[3:0];   /* Rm */
+                       read_2 = insn[15:12];
+                       
                        op0_out = regs0;
-                       if(insn[25]) begin
+                       if(!insn[25] /* immediate */) begin
                                op1_out = {20'b0, insn[11:0]};
                                carry_out = incpsr[`CPSR_C];
                        end else begin
                                op1_out = shift_res;
                                carry_out = shift_cflag_out;
                        end
+                       op2_out = regs2;
                end
-               `DECODE_LDMSTM: begin           /* Block data transfer */
+               `DECODE_LDMSTM:         /* Block data transfer */
+               begin
+                       read_0 = insn[19:16];
+                       
                        op0_out = regs0;
                        op1_out = {16'b0, insn[15:0]};
                end
-               `DECODE_BRANCH: begin           /* Branch */
+               `DECODE_BRANCH:         /* Branch */
+               begin
                        op0_out = {{6{insn[23]}}, insn[23:0], 2'b0};
                end
-               `DECODE_LDCSTC: begin           /* Coprocessor data transfer */
+               `DECODE_LDCSTC:         /* Coprocessor data transfer */
+               begin
+                       read_0 = insn[19:16];
+                       
                        op0_out = regs0;
                        op1_out = {24'b0, insn[7:0]};
                end
-               `DECODE_CDP: begin              /* Coprocessor data op */
+               `DECODE_CDP:            /* Coprocessor data op */
+               begin
                end
-               `DECODE_MRCMCR: begin           /* Coprocessor register transfer */
+               `DECODE_MRCMCR:         /* Coprocessor register transfer */
+               begin
+                       read_0 = insn[15:12];
+                       
                        op0_out = regs0;
                end
-               `DECODE_SWI: begin              /* SWI */
+               `DECODE_SWI:            /* SWI */
+               begin
                end
-               default: begin end
+               default:
+                       $display("Undecoded instruction");
                endcase
        end
 
+       
        always @ (posedge clk) begin
-               op0 <= op0_out;   /* Rn - always */
-               op1 <= op1_out; /* 'operand 2' - Rm */
-               op2 <= op2_out;   /* thirdedge - Rs */
-               carry <= carry_out;
+               if (!stall)
+               begin
+                       op0 <= op0_out;   /* Rn - always */
+                       op1 <= op1_out; /* 'operand 2' - Rm */
+                       op2 <= op2_out;   /* thirdedge - Rs */
+                       carry <= carry_out;
+                       outcpsr <= incpsr;
+                       outspsr <= inspsr;
+               end
        end
 
 endmodule
@@ -248,7 +256,7 @@ module IREALLYHATEARMSHIFT(
        assign shift_amt = insn[4] ? {|reg_amt[7:5], reg_amt[4:0]}     /* reg-specified shift */
                                   : {insn[11:7] == 5'b0, insn[11:7]}; /* immediate shift */
 
-       SuckLessShifter biteme(.oper(operand),
+       SuckLessShifter barrel(.oper(operand),
                               .carryin(cflag_in),
                               .amt(shift_amt),
                               .is_arith(is_arith),
@@ -338,3 +346,4 @@ module SuckLessRotator(
        assign res    = amt[0] ? {stage3[1:0], stage3[31:2]} : stage3;
 
 endmodule
+
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