1 files changed, 80 insertions, 13 deletions

diff --git a/nqdasm.c b/nqdasm.c
index a7020eb..0ecc5b1 100644
--- a/nqdasm.c
+++ b/nqdasm.c
@@ -1,8 +1,25 @@
+#include <errno.h>
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
 #include "mnemonics.h"
 
+#define ERROR(prog,...) \
+	do { \
+		fprintf(stderr, "%s: ", prog); \
+		fprintf(stderr, __VA_ARGS__); \
+		fprintf(stderr, "\n"); \
+	} while (0)
+
+#define PERROR(prog,str) \
+	do { \
+		int err = errno; \
+		fprintf(stderr, "%s: ", prog); \
+		errno = err; \
+		perror(str); \
+	} while (0)
+
 static const struct mnemonic *match_instruction(unsigned bits)
 {
 	for (int i = 0; i < MNEM_LAST; i++) {
@@ -12,34 +29,84 @@ static const struct mnemonic *match_instruction(unsigned bits)
 	return NULL;
 }
 
-static void print_operand(unsigned bits, const struct operand *op)
+static void print_operand(FILE *out, unsigned bits, const struct operand *op)
 {
 	switch (op->type) {
-	case REG:    printf( "r%d",      7 & (bits >> op->shift)); break;
-	case REGPTR: printf("@r%d",      7 & (bits >> op->shift)); break;
-	case IMM:    printf(  "%d", (uint8_t)(bits >> op->shift)); break;
-	case PCOFF:  printf(  "%d",  (int8_t)(bits >> op->shift)); break;
+	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;
 	}
 }
 
-int main()
+static void usage(const char *progname)
+{
+	printf("usage: %s [-o output] [input]\n", progname);
+	printf("       %s -h\n", progname);
+	printf("\n");
+	printf("\t%-16s %s\n", "-h",        "display this help text and exit");
+	printf("\t%-16s %s\n", "-o output", "write output to 'output' (default=stdout)");
+	printf("\t%-16s %s\n", "input",     "read input from 'input' (default=stdin)");
+}
+
+int main(int argc, char **argv)
 {
+	const char *outname = NULL;
+	int error = 0;
+
+	extern int   optind;
+	extern char *optarg;
+	for (int opt; (opt = getopt(argc, argv, "+ho:")) != -1;) {
+		switch (opt) {
+		case 'h':
+			usage(argv[0]);
+			return 0;
+		case 'o':
+			outname = optarg;
+			break;
+		default:
+			error = 1;
+		}
+	}
+
+	if (optind < argc - 1) {
+		ERROR(argv[0], "Too many input files");
+		return 1;
+	}
+	if (error) return 1;
+
+	FILE *in  = stdin;
+	FILE *out = stdout;
+
+	if (optind < argc && !(in = fopen(argv[optind], "r"))) {
+		PERROR(argv[0], "Error opening input file");
+		return 1;
+	}
+	if (outname && !(out = fopen(outname, "w"))) {
+		PERROR(argv[0], "Error opening output file");
+		fclose(in);
+		return 1;
+	}
+
 	unsigned bits;
-	while (scanf(" %x\n", &bits) > 0) {
+	while (fscanf(in, " %x\n", &bits) > 0) {
 		const struct mnemonic *m = match_instruction(bits);
 		if (!m) {
-			printf("\t.word   0x%04x\n", bits);
+			fprintf(out, "\t.word   0x%04x\n", bits);
 			continue;
 		}
 
-		printf("\t%s", m->mnem);
+		fprintf(out, "\t%s", m->mnem);
 		for (int i = 0; i < 3 && m->operands[i].type; i++) {
-			if (i) printf(", ");
-			else   printf("%*s", 8 - (int)strlen(m->mnem), "");
-			print_operand(bits, m->operands + i);
+			if (i) fprintf(out, ", ");
+			else   fprintf(out, "%*s", 8 - (int)strlen(m->mnem), "");
+			print_operand(out, bits, m->operands + i);
 		}
-		printf("\n");
+		fprintf(out, "\n");
 	}
+
+	fclose(in);
+	fclose(out);
 	return 0;
 }