listamsb: allow giving an output filename.

1 files changed, 15 insertions, 1 deletions

diff --git a/listamsb.c b/listamsb.c
index a289eca..88c465a 100644
--- a/listamsb.c
+++ b/listamsb.c
@@ -94,6 +94,8 @@ int printing    = 0;
 FILE *infile;
 FILE *outfile;
 
+const char *outname = NULL;
+
 void verbose(int level, const char *fmt, ...) {
 	va_list ap;
 
@@ -472,7 +474,7 @@ void unlock_program(void) {
 void print_help(void) {
 	printf("%s v" VERSION " - detokenize Atari Microsoft BASIC files\n", self);
 	puts("By B. Watson <urchlay@slackware.uk>, released under the WTFPL");
-	printf("Usage: %s [[-l] | [-a] [-v] [-h] [-i] [-n] [-u] [-t] [-m] [-s] [-r *start,end*]] [file]\n", self);
+	printf("Usage: %s [[-l] | [-[avhinutms] ... ] [-r *start,end*]] <file> <outfile>\n", self);
 	puts("  -a: raw ATASCII output");
 	puts("  -c: check only (no listing)");
 	puts("  -l: lock or unlock program");
@@ -483,6 +485,7 @@ void print_help(void) {
 	puts("  --version:  print version number and exit");
 	puts("  -i -u -t -m -s: passed to a8cat (try 'a8cat -h')");
 	puts("file must be a tokenized (SAVEd) AMSB file. if not given, reads from stdin.");
+	puts("if outfile not given, writes to stdout (via pipe to a8cat)");
 }
 
 void version(void) {
@@ -570,6 +573,17 @@ void parse_args(int argc, char **argv) {
 			os_err("%s: %s", argv[optind], strerror(errno));
 		}
 	}
+
+	optind++;
+	if(optind < argc) {
+		/* we were passed an output file */
+		outname = argv[optind];
+		if(check_only)
+			os_err("can't use output filename %s with -c", outname);
+		if(!freopen(outname, "wb", stdout))
+			os_err("%s: %s", outname, strerror(errno));
+		verbose(1, "redirected stdout to %s", outname);
+	}
 }
 
 void open_output() {