M projects/06/assembler2/assembler2.c → projects/06/assembler2/assembler2.c

@@ -142,8 +142,30 @@ }
 
 bool parse_c_type_dest(const char *dest_line, uint16_t *dest)
 {
-	// also length check here since it's not being done in parse_c_type()
-	*dest = 0x05;
+	size_t i;
+	uint8_t a_dest = 0, d_dest = 0, m_dest = 0;
+
+	for (i = 0; dest_line[i] != '='; ++i) {
+		switch (dest_line[i]) {
+		case 'A': ++a_dest; break;
+		case 'D': ++d_dest; break;
+		case 'M': ++m_dest; break;
+		default: return  err("error: invalid destination register "
+			               "'%c'\n", dest_line[i]);
+		}
+
+		if (i >= 3)
+			return err("error: too many destinations\n");
+	}
+
+	if (a_dest > 1)
+		return err("err: multiple 'A's found in destination\n");
+	if (d_dest > 1)
+		return err("err: multiple 'D's found in destination\n");
+	if (m_dest > 1)
+		return err("err: multiple 'M's found in destination\n");
+
+	*dest = (uint16_t)((a_dest << 2) | (d_dest << 1) | (m_dest));
 	return true;
 }