add (if cond if-true if-false) builtin

1 files changed, 24 insertions, 1 deletions

diff --git a/vm.c b/vm.c
index 205e0fd..70aca3d 100644
--- a/vm.c
+++ b/vm.c
@@ -55,6 +55,7 @@ int runvm(State *S) {
 	disasm_chunk(ch);
 
 #define RBYTE() (ch->bc.d[th->ip++])
+#define RSHORT() (th->ip += 2, (uint16_t)( ch->bc.d[th->ip-2] | ch->bc.d[th->ip-1] << 8 ))
 
 #define PUSH(v) th->stack[th->sp++] = v;
 #define POP()   (th->stack[--th->sp])
@@ -85,6 +86,24 @@ int runvm(State *S) {
 			--th->sp;
 			break;
 
+		case OP_SKIP: {
+			uint16_t offset = RSHORT();
+			th->ip += offset;
+			break;
+		}
+		case OP_REDO: {
+			uint16_t offset = RSHORT();
+			th->ip -= offset;
+			break;
+		}
+		case OP_0BRANCH: {
+			uint16_t offset = RSHORT();
+			bool cond = is_truthy(POP());
+			if (!cond)
+				th->ip += offset;
+			break;
+		}
+
 		case OP_GETGLOBAL: {
 			uint8_t cix = RBYTE();
 			Val varname = ch->consts.d[cix];
@@ -134,12 +153,16 @@ int runvm(State *S) {
 		case OP_TRUE: PUSH(VAL_TRUE); break;
 		case OP_FALSE: PUSH(VAL_FALSE); break;
 
-
 		}
 	}
 	done:;
 	return status;
 }
 
+#undef RBYTE
+#undef RSHORT
+#undef PUSH
+#undef POP
+#undef PEEK