nqasm: allow specifying labels for operands

1 files changed, 57 insertions, 3 deletions

diff --git a/nqasm.c b/nqasm.c
index 738f815..0b0bbd8 100644
--- a/nqasm.c
+++ b/nqasm.c
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <stdint.h>
 #include <stdio.h>
 
@@ -15,6 +16,12 @@ struct label {
 
 uint16_t addr;
 
+static int cmp_label(const void *a, const void *b)
+{
+	const struct label *la = a, *lb = b;
+	return strcmp(la->name, lb->name);
+}
+
 #define DEFINE_VECTOR(name, arraytype, arrayname, initsize) \
 	static struct name { \
 		struct vector v; \
@@ -49,7 +56,25 @@ void add_instruction(const struct instruction *inst)
 	addr += 2;
 }
 
-static void assemble_instruction(const struct instruction *inst)
+static long eval_argument(const struct argument *arg)
+{
+	struct label *l;
+	switch (arg->type) {
+	case ARG_INTEGER:
+		return arg->value;
+
+	case ARG_LABEL:
+		l = vector_search(&labels->v, &(struct label) { .name = arg->label }, cmp_label);
+		if (l) return l->addr;
+		fprintf(stderr, "unknown label '%s'\n", arg->label);
+		exit(1);
+
+	default:
+		assert(0);
+	}
+}
+
+static void assemble_instruction(const struct instruction *inst, uint16_t pc)
 {
 	const struct mnemonic *mnem = &mnemonics[inst->mnem];
 	uint16_t bits = mnem->bits;
@@ -57,7 +82,34 @@ static void assemble_instruction(const struct instruction *inst)
 	const struct operand  *ops  = mnem->operands;
 	const struct argument *args = inst->args.args;
 	for (int i = 0; i < 3 && ops[i].type; i++) {
-		bits |= args[i].value << ops[i].shift;
+		long value = eval_argument(args + i);
+
+		switch (ops[i].type) {
+		case REG:
+		case REGPTR:
+			if (0 > value || value >= 8) {
+				fprintf(stderr, "invalid register\n");
+				exit(1);
+			}
+			break;
+		case IMM:
+			if (-0x80 > value || value > 0xff) {
+				fprintf(stderr, "immediate operand out of range\n");
+				exit(1);
+			}
+			break;
+		case PCOFF:
+			value -= pc;
+			if (-0x80 > value || value > 0x7f) {
+				fprintf(stderr, "pc offset operand out of range\n");
+				exit(1);
+			}
+			break;
+		default:
+			assert(0);
+		}
+
+		bits |= (value & 255) << ops[i].shift;
 	}
 
 	printf("%04x\n", bits);
@@ -84,8 +136,10 @@ int main(int argc, char **argv)
 
 	yyparse();
 
+	vector_sort(&labels->v, cmp_label);
+
 	for (size_t i = 0; i < instrs->v.count; i++) {
-		assemble_instruction(instrs->i + i);
+		assemble_instruction(instrs->i + i, 2 * i);
 	}
 
 	return 0;