M xywasm.c → xywasm.c

@@ -62,6 +62,32 @@ TOKEN_END_COMMENT,
     TOKEN_END_INVALID
 } xyw_token_terminator;
 
+typedef enum
+{
+    M_NOM = 0, // no nodes
+    M_ONW,     // Only w
+    M_EXC,     // x or y and w
+    M_ALL      // all modes
+} xyw_allowed_modes;
+
+const xyw_byte xyw_instruction_modes[] = {
+//  "HLT", "NOP", "PSH", "POP",
+    M_NOM, M_NOM, M_ALL, M_ALL,
+// "LDB", "LDW", "STB", "STW",
+    M_ALL, M_ALL, M_ALL, M_ALL,
+//  "INC", "DEC", "SHL", "SHR",
+    M_ALL, M_ALL, M_ALL, M_ALL,
+//  "ADD", "SUB", "MUL", "DIV",
+    M_ALL, M_ALL, M_ALL, M_ALL,
+//  "EQU", "NEQ", "GTH", "LTH",
+    M_ALL, M_ALL, M_ALL, M_ALL,
+//  "NOT", "AND", "IOR", "XOR",
+    M_ALL, M_ALL, M_ALL, M_ALL,
+//  "DUP", "SWP", "OVR", "ROT",
+    M_ALL, M_ALL, M_ONW, M_ONW,
+//  "JMP", "JCN", "JSR", "RTS"
+    M_EXC, M_EXC, M_EXC, M_NOM};
+
 // The token being processed
 static char token[TOKEN_MAX_LENGTH];
 static unsigned int token_length = 0;
@@ -408,6 +434,37 @@ }
     return 0;
 }
 
+// Returns 1 if modes are valid for instr, 0 otherwise.
+static int validate_instruction_modes(xyw_context *ctx, xyw_byte instr, xyw_byte modes)
+{
+    xyw_byte result = 0;
+    switch (modes)
+    {
+        case M_NOM:
+            result = !((instr & XYW_MODE_X) || (instr & XYW_MODE_Y) || (instr & XYW_MODE_W)); 
+            if (!result) {
+                token_error("Instruction does not support any modes.");
+            }
+            break;
+        case M_ONW:
+            result = !((instr & XYW_MODE_X) || (instr & XYW_MODE_Y));
+            if (!result) {
+                token_error("Instruction only supports W mode.");
+            }
+            break;
+        case M_EXC:
+            result = !((instr & XYW_MODE_X) && (instr & XYW_MODE_Y));
+            if (!result) {
+                token_error("Instruction only supports X or Y mode, not both.");
+            }
+            break;
+        case M_ALL:
+            result = 1;
+            break;
+    }
+    return result;
+}
+
 static int process_instruction(xyw_context *ctx)
 {
     (void)ctx;
@@ -418,6 +475,7 @@ {
         if (strcmpn(token, xyw_instructions[i], 3) == 0)
         {
             opcode = (xyw_byte)i;
+            xyw_byte modes = xyw_instruction_modes[opcode];
             // There could be 0 to 3 modes (x y z) after the mnemonic in any order
             if (token_length > 3)
             {
@@ -439,6 +497,10 @@ else if (mode_char == 'w' || mode_char == 'W')
                     {
                         opcode |= XYW_MODE_W;
                         mode_found = 1;
+                    }
+                    if (!validate_instruction_modes(ctx, opcode, modes))
+                    {
+                        return -1;
                     }
                     if (!mode_found)
                     {