nqdasm: Factor out operand value extraction code

1 files changed, 28 insertions, 10 deletions

diff --git a/nqdasm.c b/nqdasm.c
index 86f8560..e0f78fc 100644
--- a/nqdasm.c
+++ b/nqdasm.c
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -38,13 +39,29 @@ static const struct mnemonic *match_instruction(unsigned bits)
 	return NULL;
 }
 
-static void print_operand(FILE *out, unsigned bits, const struct operand *op)
+static inline int get_argvalue(const struct line *line, int argidx)
 {
+	const struct operand *op = line->mnem->operands + argidx;
 	switch (op->type) {
-	case REG:    fprintf(out,  "r%d",      7 & (bits >> op->shift)); break;
-	case REGPTR: fprintf(out, "@r%d",      7 & (bits >> op->shift)); break;
-	case IMM:    fprintf(out,   "%d", (uint8_t)(bits >> op->shift)); break;
-	case PCOFF:  fprintf(out,   "%d",  (int8_t)(bits >> op->shift)); break;
+	case REG:
+	case REGPTR: return       7 & (line->value >> op->shift);
+	case IMM:    return (uint8_t) (line->value >> op->shift);
+	case PCOFF:  return  (int8_t) (line->value >> op->shift);
+	}
+	assert(0);
+}
+
+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;
+	const struct operand *op = inst->mnem->operands + argidx;
+
+	switch (op->type) {
+	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;
+	default: assert(0);
 	}
 }
 
@@ -98,8 +115,9 @@ static void disassemble(FILE *in, FILE *out)
 	if (!lines) return;
 
 	for (size_t i = 0; i < count; i++) {
-		unsigned bits = lines[i].value;
-		const struct mnemonic *m = lines[i].mnem;
+		const struct line *line  = lines + i;
+		unsigned bits            = line->value;
+		const struct mnemonic *m = line->mnem;
 
 		if (!m) {
 			fprintf(out, "\t.word   0x%04x\n", bits);
@@ -107,10 +125,10 @@ static void disassemble(FILE *in, FILE *out)
 		}
 
 		fprintf(out, "\t%s", m->mnem);
-		for (int i = 0; i < 3 && m->operands[i].type; i++) {
-			if (i) fprintf(out, ", ");
+		for (int j = 0; j < 3 && m->operands[j].type; j++) {
+			if (j) fprintf(out, ", ");
 			else   fprintf(out, "%*s", 8 - (int)strlen(m->mnem), "");
-			print_operand(out, bits, m->operands + i);
+			print_operand(out, lines, count, i, j);
 		}
 		fprintf(out, "\n");
 	}