nqdasm: Generate necessary labels for pcoff operands

1 files changed, 48 insertions, 1 deletions

diff --git a/nqdasm.c b/nqdasm.c
index e0f78fc..d7016fb 100644
--- a/nqdasm.c
+++ b/nqdasm.c
@@ -28,6 +28,7 @@ struct line {
 	const struct mnemonic *mnem;
 	uint16_t addr;
 	uint16_t value;
+	int      label;
 };
 
 static const struct mnemonic *match_instruction(unsigned bits)
@@ -51,6 +52,41 @@ static inline int get_argvalue(const struct line *line, int argidx)
 	assert(0);
 }
 
+static int cmp_line_addr(const void *a, const void *b)
+{
+	const struct line *la = (const struct line*)a;
+	const struct line *lb = (const struct line*)b;
+	return la->addr < lb->addr ? -1 : la->addr == lb->addr ? 0 : 1;
+}
+
+static struct line *get_pcoff_target(const struct line *lines, size_t count, const struct line *inst, int argidx)
+{
+	uint16_t targetaddr = inst->addr + get_argvalue(inst, argidx);
+	return bsearch(&(struct line){ .addr = targetaddr }, lines, count, sizeof *lines, cmp_line_addr);
+}
+
+static void assign_labels(struct line *lines, size_t count)
+{
+	/* mark those addresses that need a label */
+	for (size_t i = 0; i < count; i++) {
+		if (!lines[i].mnem) continue;
+
+		const struct operand *ops = lines[i].mnem->operands;
+		for (int j = 0; j < 3 && ops[j].type; j++) {
+			if (ops[j].type == PCOFF) {
+				struct line *target = get_pcoff_target(lines, count, lines + i, j);
+				if (target) target->label = 1;
+			}
+		}
+	}
+
+	/* assign labels in ascending order */
+	int label = 0;
+	for (size_t i = 0; i < count; i++) {
+		lines[i].label = lines[i].label ? label++ : -1;
+	}
+}
+
 static void print_operand(FILE *out, const struct line *lines, size_t count, size_t lineidx, size_t argidx)
 {
 	const struct line  *inst = lines + lineidx;
@@ -60,7 +96,14 @@ static void print_operand(FILE *out, const struct line *lines, size_t count, siz
 	case REG:    fprintf(out,  "r%d", get_argvalue(inst, argidx)); break;
 	case REGPTR: fprintf(out, "@r%d", get_argvalue(inst, argidx)); break;
 	case IMM:    fprintf(out,   "%d", get_argvalue(inst, argidx)); break;
-	case PCOFF:  fprintf(out,   "%d", get_argvalue(inst, argidx)); break;
+	case PCOFF: {
+			const struct line *target = get_pcoff_target(lines, count, inst, argidx);
+			if (target && target->label >= 0)
+				fprintf(out, "L%d", target->label);
+			else
+				fprintf(out, "%d", get_argvalue(inst, argidx));
+			break;
+		}
 	default: assert(0);
 	}
 }
@@ -114,11 +157,15 @@ static void disassemble(FILE *in, FILE *out)
 	struct line *lines = read_lines(in, &count);
 	if (!lines) return;
 
+	assign_labels(lines, count);
+
 	for (size_t i = 0; i < count; i++) {
 		const struct line *line  = lines + i;
 		unsigned bits            = line->value;
 		const struct mnemonic *m = line->mnem;
 
+		if (line->label >= 0) fprintf(out, "L%d:", line->label);
+
 		if (!m) {
 			fprintf(out, "\t.word   0x%04x\n", bits);
 			continue;