Added opcode OP_DUP_*

Duplicates the nth datum off the stack, pushing it to the top.  Useful
for operations such as MOV which eat the stack.

2 files changed, 25 insertions, 0 deletions

diff --git a/src/inst.c b/src/inst.c
index fc02b66..8a5ce2c 100644
--- a/src/inst.c
+++ b/src/inst.c
@@ -59,6 +59,15 @@ const char *opcode_as_cstr(opcode_t code)
   case OP_MOV_HWORD:
     return "MOV_HWORD";
     break;
+  case OP_DUP_BYTE:
+    return "DUP_BYTE";
+    break;
+  case OP_DUP_HWORD:
+    return "DUP_HWORD";
+    break;
+  case OP_DUP_WORD:
+    return "DUP_WORD";
+    break;
   case OP_NOT_BYTE:
     return "NOT_BYTE";
     break;
@@ -182,6 +191,11 @@ void inst_print(inst_t instruction, FILE *fp)
     fprintf(fp, "reg=0x");
     data_print(instruction.operand, DATA_TYPE_BYTE, fp);
   }
+  else if (OPCODE_IS_TYPE(instruction.opcode, OP_DUP))
+  {
+    fprintf(fp, "n=");
+    data_print(instruction.operand, DATA_TYPE_WORD, fp);
+  }
   fprintf(fp, ")");
 }
 
@@ -218,6 +232,8 @@ void inst_write_bytecode(inst_t inst, darr_t *darr)
   else if (OPCODE_IS_TYPE(inst.opcode, OP_PUSH_REGISTER) ||
            OPCODE_IS_TYPE(inst.opcode, OP_MOV))
     to_append = DATA_TYPE_BYTE;
+  else if (OPCODE_IS_TYPE(inst.opcode, OP_DUP))
+    to_append = DATA_TYPE_WORD;
 
   switch (to_append)
   {
@@ -292,6 +308,8 @@ inst_t inst_read_bytecode(darr_t *darr)
   else if (OPCODE_IS_TYPE(opcode, OP_PUSH_REGISTER) ||
            OPCODE_IS_TYPE(opcode, OP_MOV))
     inst.operand = read_type_from_darr(darr, DATA_TYPE_BYTE);
+  else if (OPCODE_IS_TYPE(opcode, OP_DUP))
+    inst.operand = read_type_from_darr(darr, DATA_TYPE_WORD);
   // Otherwise opcode doesn't take operands
 
   inst.opcode = opcode;
diff --git a/src/inst.h b/src/inst.h
index 1073593..16374ee 100644
--- a/src/inst.h
+++ b/src/inst.h
@@ -40,6 +40,10 @@ typedef enum
   OP_MOV_HWORD,
   OP_MOV_WORD,
 
+  OP_DUP_BYTE,
+  OP_DUP_HWORD,
+  OP_DUP_WORD,
+
   // Boolean operations
   OP_NOT_BYTE,
   OP_NOT_HWORD,
@@ -108,6 +112,9 @@ inst_t *insts_read_bytecode_file(FILE *, size_t *);
 #define INST_PUSH_REG(TYPE, REG) \
   ((inst_t){.opcode = OP_PUSH_REGISTER_##TYPE, .operand = D##TYPE(REG)})
 
+#define INST_DUP(TYPE, OP) \
+  ((inst_t){.opcode = OP_DUP_##TYPE, .operand = DWORD(OP)})
+
 #define INST_NOT(TYPE) ((inst_t){.opcode = OP_NOT_##TYPE})
 #define INST_OR(TYPE)  ((inst_t){.opcode = OP_OR_##TYPE})
 #define INST_AND(TYPE) ((inst_t){.opcode = OP_AND_##TYPE})