Implement limited integer literal parsing

1 files changed, 14 insertions, 15 deletions

diff --git a/tpu.c b/tpu.c
index d95d8a9..55e4d53 100644
--- a/tpu.c
+++ b/tpu.c
@@ -96,7 +96,7 @@ label_map_link_pos(struct label_map *map, const char *name)
 }
 
 bool
-label_map_add(struct label_map *map, const char *name, size_t pc)
+label_map_add(struct label_map *map, const char *name, int pc)
 {
 	struct label_map_link **pos, *link;
 
@@ -117,13 +117,13 @@ label_map_add(struct label_map *map, const char *name, size_t pc)
 	return true;
 }
 
-size_t
+int
 label_map_get(struct label_map *map, const char *name)
 {
 	struct label_map_link **link;
 
 	link = label_map_link_pos(map, name);
-	if (!*link) return TPU_MAX_INST_CNT;
+	if (!*link) return -1;
 
 	return (*link)->pc;
 }
@@ -338,7 +338,7 @@ tpu_port_read(struct tpu *tpu, enum tpu_port_dir dir)
 }
 
 static bool
-tpu_port_write(struct tpu *tpu, enum tpu_port_dir dir, uint8_t lit)
+tpu_port_write(struct tpu *tpu, enum tpu_port_dir dir, int lit)
 {
 	struct tpu_port *port;
 
@@ -354,11 +354,8 @@ tpu_port_write(struct tpu *tpu, enum tpu_port_dir dir, uint8_t lit)
 static void
 tpu_jmp_label(struct tpu *tpu, const char *label)
 {
-	size_t pc;
-
-	pc = label_map_get(&tpu->label_map, label);
-	if (pc >= TPU_MAX_INST_CNT) abort();
-	tpu->pc = (uint8_t) pc;
+	tpu->pc = label_map_get(&tpu->label_map, label);
+	if (tpu->pc < 0 || tpu->pc >= tpu->inst_cnt) abort();
 }
 
 int
@@ -378,7 +375,7 @@ tpu_exec_get(struct tpu *tpu, struct tpu_inst_op *op)
 			v = tpu_port_read(tpu, (enum tpu_port_dir) i);
 			if (v >= 0) {
 				tpu->last = i;
-				return (uint8_t) v;
+				return v;
 			}
 		}
 		return -1;
@@ -393,7 +390,7 @@ tpu_exec_get(struct tpu *tpu, struct tpu_inst_op *op)
 }
 
 bool
-tpu_exec_put(struct tpu *tpu, struct tpu_inst_op *op, uint8_t lit)
+tpu_exec_put(struct tpu *tpu, struct tpu_inst_op *op, int lit)
 {
 	int i;
 
@@ -432,7 +429,7 @@ tpu_exec_mov(struct tpu *tpu, struct tpu_inst *inst)
 	lit = tpu_exec_get(tpu, &inst->ops[0]);
 	if (lit < 0) return STATUS_READ;
 
-	if (!tpu_exec_put(tpu, &inst->ops[1], (uint8_t) lit))
+	if (!tpu_exec_put(tpu, &inst->ops[1], lit))
 		return STATUS_WRITE;
 
 	return STATUS_RUN;
@@ -467,13 +464,13 @@ tpu_exec(struct tpu *tpu, struct tpu_inst *inst)
 	case INST_ADD:
 		val = tpu_exec_get(tpu, &inst->ops[0]);
 		if (val < 0) return STATUS_READ;
-		tpu->acc += (uint8_t) val;
+		tpu->acc = MIN(MAX(tpu->acc + val, -999), 999);
 		tpu->pc += 1;
 		return STATUS_RUN;
 	case INST_SUB:
 		val = tpu_exec_get(tpu, &inst->ops[0]);
 		if (val < 0) return STATUS_READ;
-		tpu->acc -= (uint8_t) val;
+		tpu->acc = MIN(MAX(tpu->acc - val, -999), 999);
 		tpu->pc += 1;
 		return STATUS_RUN;
 	case INST_NEG:
@@ -509,7 +506,9 @@ tpu_exec(struct tpu *tpu, struct tpu_inst *inst)
 		return STATUS_RUN;
 	case INST_JRO:
 		tpu->pc += inst->ops[0].val.lit;
-		if (tpu->pc >= tpu->inst_cnt) tpu->pc = 0;
+		if (tpu->pc < 0) tpu->pc = 0;
+		if (tpu->pc >= tpu->inst_cnt)
+			tpu->pc = (int) tpu->inst_cnt - 1;
 		return STATUS_RUN;
 	default:
 		abort();