Ok, move read_0, read_1, read_2 back into a unified block again.

[firearm.git] / Decode.v

diff --git a/Decode.v b/Decode.v
index 506480d81de2934d28c551379263e46cdc140007..fd8554bb8ecde600d59e8256dc1dff7029963106 100644 (file)
--- a/Decode.v
+++ b/Decode.v
@@ -63,58 +63,82 @@ module Decode(
                        rpc = 32'hxxxxxxxx;
                endcase
 
-       always @(*)
+       always @(*) begin
+               read_0 = 4'hx;
+               read_1 = 4'hx;
+               read_2 = 4'hx;
+               
                casez (insn)
                32'b????000000??????????????1001????:   /* 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 */
+               end
 //             32'b????00001???????????????1001????,   /* Multiply long */
 //                     read_0 = insn[11:8]; /* Rn */
+//                     read_1 = insn[3:0];   /* Rm */
+//                     read_2 = 4'b0;       /* anyus */
                32'b????00010?001111????000000000000,   /* MRS (Transfer PSR to register) */
                32'b????00010?101001111100000000????,   /* MSR (Transfer register to PSR) */
                32'b????00?10?1010001111????????????:   /* MSR (Transfer register or immediate to PSR, flag bits only) */
-                       read_0 = 4'hx;
+               begin end       /* Everything stays x'ed out. */
                32'b????00??????????????????????????:   /* ALU */
+               begin
                        read_0 = insn[19:16]; /* Rn */
+                       read_1 = insn[3:0];   /* Rm */
+                       read_2 = insn[11:8];  /* Rs for shift */
+               end
                32'b????00010?00????????00001001????:   /* Atomic swap */
+               begin
                        read_0 = insn[19:16]; /* Rn */
+                       read_1 = insn[3:0];   /* Rm */
+               end
                32'b????000100101111111111110001????:   /* Branch and exchange */
                        read_0 = insn[3:0];   /* Rn */
                32'b????000??0??????????00001??1????:   /* Halfword transfer - register offset */
+               begin
                        read_0 = insn[19:16];
-               32'b????000??1??????????00001??1????:   /* Halfword transfer - register offset */
+                       read_1 = insn[3:0];
+               end
+               32'b????000??1??????????00001??1????:   /* Halfword transfer - immediate offset */
+               begin
                        read_0 = insn[19:16];
+                       read_1 = insn[3:0];
+               end
                32'b????011????????????????????1????:   /* Undefined. I hate ARM */
-                       read_0 = 4'hx;
+               begin end
                32'b????01??????????????????????????:   /* Single data transfer */
+               begin
                        read_0 = insn[19:16]; /* Rn */
+                       read_1 = insn[3:0];   /* Rm */
+               end
                32'b????100?????????????????????????:   /* Block data transfer */
                        read_0 = insn[19:16];
                32'b????101?????????????????????????:   /* Branch */
-                       read_0 = 4'hx;
+               begin end
                32'b????110?????????????????????????:   /* Coprocessor data transfer */
                        read_0 = insn[19:16];
                32'b????1110???????????????????0????,   /* Coprocessor data op */
                32'b????1110???????????????????1????,   /* Coprocessor register transfer */
                32'b????1111????????????????????????:   /* SWI */
-                       read_0 = 4'hx;
+               begin end
                default:
-                       read_0 = 4'hx;
+                       $display("Undecoded instruction");
                endcase
-
-       always @ (*) begin
+       end
+       
+       always @(*) begin
+               op1_res = 32'hxxxxxxxx;
+               cpsr = 32'hxxxxxxxx;
                casez (insn)
                32'b????000000??????????????1001????: begin /* Multiply */
-                       read_1 = insn[3:0];   /* Rm */
-                       read_2 = insn[11:8];  /* Rs */
                        op1_res = regs1;
                        cpsr = incpsr;
                end
-/*             32'b????00001???????????????1001????: begin * Multiply long *
-                       
-                       read_1 = insn[3:0];  * Rm *
-                       read_2 = 4'b0;       * anyus *
-                       op1_res = regs1;
-               end*/
+//             32'b????00001???????????????1001????: begin /* Multiply long */
+//                     op1_res = regs1;
+//             end
                32'b????00010?001111????000000000000: begin /* MRS (Transfer PSR to register) */
                        cpsr = incpsr;
                end
@@ -125,8 +149,6 @@ module Decode(
                        cpsr = incpsr;
                 end
                32'b????00??????????????????????????: begin /* ALU */
-                       read_1 = insn[3:0];   /* Rm */
-                       read_2 = insn[11:8];  /* Rs for shift */
                        if(insn[25]) begin     /* the constant case */
                                cpsr = incpsr;
                                op1_res = ({24'b0, insn[7:0]} >> {insn[11:8], 1'b0}) | ({24'b0, insn[7:0]} << (5'b0 - {insn[11:8], 1'b0}));
@@ -136,22 +158,16 @@ module Decode(
                        end
                end
                32'b????00010?00????????00001001????: begin /* Atomic swap */
-                       read_1 = insn[3:0];   /* Rm */
-                       read_2 = 4'b0;        /* anyus */
                        op1_res = regs1;
                end
                32'b????000100101111111111110001????: begin /* Branch and exchange */
                        cpsr = incpsr;
                end
                32'b????000??0??????????00001??1????: begin /* Halfword transfer - register offset */
-                       read_1 = insn[3:0];
-                       read_2 = 4'b0;
                        op1_res = regs1;
                        cpsr = incpsr;
                end
                32'b????000??1??????????00001??1????: begin /* Halfword transfer - immediate offset */
-                       
-                       read_1 = insn[3:0];
                        op1_res = {24'b0, insn[11:8], insn[3:0]};
                        cpsr = incpsr;
                end
@@ -159,7 +175,6 @@ module Decode(
                        /* eat shit */
                end
                32'b????01??????????????????????????: begin /* Single data transfer */
-                       read_1 = insn[3:0];   /* Rm */
                        if(insn[25]) begin
                                op1_res = {20'b0, insn[11:0]};
                                cpsr = incpsr;