Impl JMP by simply reusing JSR

1 files changed, 19 insertions, 11 deletions

diff --git a/disasm.cpp b/disasm.cpp
index 033349b..e4e776b 100644
--- a/disasm.cpp
+++ b/disasm.cpp
@@ -35,9 +35,15 @@ static size_t disasm_mfff0_v4e70(
     return disasm_verbatim(out, out_sz, instr_sz, instr, offset, code);
 }
 
-static size_t disasm_jsr(
-        char *out, size_t out_sz, size_t *instr_sz, uint16_t instr, uint32_t offset, const DataBuffer & code)
+enum class JsrJmp {
+    kJsr,
+    kJmp,
+};
+
+static size_t disasm_jsr_jmp(
+        char *out, size_t out_sz, size_t *instr_sz, uint16_t instr, uint32_t offset, const DataBuffer & code, JsrJmp jsrjmp)
 {
+    const char *instr_repr = (jsrjmp == JsrJmp::kJsr) ? "jsr" : "jmp";
     const int addrmode = instr & 0x3f;
     const int m = (addrmode >> 3) & 0x7;
     const int xn = addrmode & 0x7;
@@ -49,7 +55,7 @@ static size_t disasm_jsr(
         if (instr_sz) {
             *instr_sz = kInstructionSizeStepBytes;
         }
-        return Min(out_sz, snprintf(out, out_sz, "  jsr %%a%d@", xn));
+        return Min(out_sz, snprintf(out, out_sz, "  %s %%a%d@", instr_repr, xn));
     case 3: // 4e98 .. 4e9f
     case 4: // 4ea0 .. 4ea7
         break;
@@ -59,7 +65,7 @@ static size_t disasm_jsr(
                 *instr_sz = kInstructionSizeStepBytes * 2;
             }
             const int16_t dispmt = GetI16BE(code.buffer + offset + kInstructionSizeStepBytes);
-            return Min(out_sz, snprintf(out, out_sz, "  jsr %%a%d@(%d:w)", xn, dispmt));
+            return Min(out_sz, snprintf(out, out_sz, "  %s %%a%d@(%d:w)", instr_repr, xn, dispmt));
         }
     case 6: // 4eb0 .. 4eb7, Brief Extension Word
         {
@@ -72,8 +78,8 @@ static size_t disasm_jsr(
             const char size_spec = ((briefext >> 11) & 1) ? 'l' : 'w';
             const int8_t dispmt = briefext & 0xff;
             return Min(out_sz, snprintf(
-                        out, out_sz, "  jsr %%a%d@(%d,%%%c%d:%c)",
-                        xn, dispmt, reg, xn2, size_spec));
+                        out, out_sz, "  %s %%a%d@(%d,%%%c%d:%c)",
+                        instr_repr, xn, dispmt, reg, xn2, size_spec));
         }
     case 7: // 4eb8 .. 4ebf, some are with Brief Extension Word
         switch (xn) {
@@ -83,7 +89,7 @@ static size_t disasm_jsr(
                     *instr_sz = kInstructionSizeStepBytes * 2;
                 }
                 const int32_t dispmt = GetI16BE(code.buffer + offset + kInstructionSizeStepBytes);
-                return Min(out_sz, snprintf(out, out_sz, "  jsr 0x%x:w", dispmt));
+                return Min(out_sz, snprintf(out, out_sz, "  %s 0x%x:w", instr_repr, dispmt));
             }
         case 1: // 4eb9 (xxx).L
             {
@@ -91,7 +97,7 @@ static size_t disasm_jsr(
                     *instr_sz = kInstructionSizeStepBytes * 3;
                 }
                 const int32_t dispmt = GetI32BE(code.buffer + offset + kInstructionSizeStepBytes);
-                return Min(out_sz, snprintf(out, out_sz, "  jsr 0x%x:l", dispmt));
+                return Min(out_sz, snprintf(out, out_sz, "  %s 0x%x:l", instr_repr, dispmt));
             }
         case 2: // 4eba, Displacement
             {
@@ -99,7 +105,7 @@ static size_t disasm_jsr(
                     *instr_sz = kInstructionSizeStepBytes * 2;
                 }
                 const int16_t dispmt = GetI16BE(code.buffer + offset + kInstructionSizeStepBytes);
-                return Min(out_sz, snprintf(out, out_sz, "  jsr %%pc@(%d:w)", dispmt));
+                return Min(out_sz, snprintf(out, out_sz, "  %s %%pc@(%d:w)", instr_repr, dispmt));
             }
         case 3: // 4ebb
             {
@@ -113,7 +119,7 @@ static size_t disasm_jsr(
                 const char size_spec = ((briefext >> 11) & 1) ? 'l' : 'w';
                 const int8_t dispmt = briefext & 0xff;
                 return Min(out_sz, snprintf(
-                            out, out_sz, "  jsr %%pc@(%d,%%%c%d:%c)", dispmt, reg, xn2, size_spec));
+                            out, out_sz, "  %s %%pc@(%d,%%%c%d:%c)", instr_repr, dispmt, reg, xn2, size_spec));
             }
         case 4: // 4ebc
         case 5: // 4ebd
@@ -131,7 +137,9 @@ size_t m68k_disasm(
     if ((instr & 0xfff0) == 0x4e70) {
         return disasm_mfff0_v4e70(out, out_sz, instr_sz, instr, offset, code);
     } else if ((instr & 0xffc0) == 0x4e80) {
-        return disasm_jsr(out, out_sz, instr_sz, instr, offset, code);
+        return disasm_jsr_jmp(out, out_sz, instr_sz, instr, offset, code, JsrJmp::kJsr);
+    } else if ((instr & 0xffc0) == 0x4ec0) {
+        return disasm_jsr_jmp(out, out_sz, instr_sz, instr, offset, code, JsrJmp::kJmp);
     }
     return disasm_verbatim(out, out_sz, instr_sz, instr, offset, code);
 }