Ok, move read_0, read_1, read_2 back into a unified block again.
authorJoshua Wise <joshua@rebirth.joshuawise.com>
Sun, 28 Dec 2008 01:50:09 +0000 (20:50 -0500)
committerJoshua Wise <joshua@rebirth.joshuawise.com>
Sun, 28 Dec 2008 01:50:09 +0000 (20:50 -0500)
Decode.v

index 2698eca..fd8554b 100644 (file)
--- a/Decode.v
+++ b/Decode.v
@@ -63,109 +63,72 @@ 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;
-               endcase
-       
-       always @(*)
-               casez (insn)
-               32'b????000000??????????????1001????:   /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
-                       read_1 = insn[3:0];   /* Rm */
-//             32'b????00001???????????????1001????:   /* Multiply long */
-//                     read_1 = insn[3:0];   /* Rm */
-               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_1 = 4'hx;
-               32'b????00??????????????????????????:   /* ALU */
-                       read_1 = insn[3:0];   /* Rm */
-               32'b????00010?00????????00001001????:   /* Atomic swap */
-                       read_1 = insn[3:0];   /* Rm */
-               32'b????000100101111111111110001????:   /* Branch and exchange */
-                       read_1 = 4'hx;
-               32'b????000??0??????????00001??1????:   /* Halfword transfer - register offset */
-                       read_1 = insn[3:0];
-               32'b????000??1??????????00001??1????:   /* Halfword transfer - register offset */
-                       read_1 = insn[3:0];
-               32'b????011????????????????????1????:   /* Undefined. I hate ARM */
-                       read_1 = 4'hx;
-               32'b????01??????????????????????????:   /* Single data transfer */
-                       read_1 = insn[3:0];   /* Rm */
-               32'b????100?????????????????????????,   /* Block data transfer */
-               32'b????101?????????????????????????,   /* Branch */
-               32'b????110?????????????????????????,   /* Coprocessor data transfer */
-               32'b????1110???????????????????0????,   /* Coprocessor data op */
-               32'b????1110???????????????????1????,   /* Coprocessor register transfer */
-               32'b????1111????????????????????????:   /* SWI */
-                       read_1 = 4'hx;
-               default:
-                       read_1 = 4'hx;
+                       $display("Undecoded instruction");
                endcase
+       end
        
-       always @(*)
-               casez (insn)
-               32'b????000000??????????????1001????:   /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
-                       read_2 = insn[11:8];  /* Rs */
-//             32'b????00001???????????????1001????:   /* Multiply long */
-//                     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_2 = 4'hx;
-               32'b????00??????????????????????????:   /* ALU */
-                       read_2 = insn[11:8];  /* Rs for shift */
-               32'b????00010?00????????00001001????,   /* Atomic swap */
-               32'b????000100101111111111110001????,   /* Branch and exchange */
-               32'b????000??0??????????00001??1????,   /* Halfword transfer - register offset */
-               32'b????000??1??????????00001??1????,   /* Halfword transfer - register offset */
-               32'b????011????????????????????1????,   /* Undefined. I hate ARM */
-               32'b????01??????????????????????????,   /* Single data transfer */
-               32'b????100?????????????????????????,   /* Block data transfer */
-               32'b????101?????????????????????????,   /* Branch */
-               32'b????110?????????????????????????,   /* Coprocessor data transfer */
-               32'b????1110???????????????????0????,   /* Coprocessor data op */
-               32'b????1110???????????????????1????,   /* Coprocessor register transfer */
-               32'b????1111????????????????????????:   /* SWI */
-                       read_2 = 4'hx;
-               default:
-                       read_2 = 4'hx;
-               endcase
-
-       always @ (*) begin
+       always @(*) begin
                op1_res = 32'hxxxxxxxx;
                cpsr = 32'hxxxxxxxx;
                casez (insn)
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