1 files changed, 83 insertions, 8 deletions

diff --git a/bas.c b/bas.c
index 64c4f3f..230032c 100644
--- a/bas.c
+++ b/bas.c
@@ -27,24 +27,50 @@ const char *self;
 unsigned char program[BUFSIZE];
 FILE *input_file;
 FILE *output_file;
+char *output_filename = NULL;
 
 void die(const char *msg) {
 	fprintf(stderr, "%s: %s\n", self, msg);
 	exit(1);
 }
 
+void parse_general_args(int argc, char **argv, void (*helpfunc)()) {
+	if(argc < 2) {
+		(*helpfunc)();
+		exit(1);
+	}
+
+	if(strcmp(argv[1], "--help") == 0) {
+		(*helpfunc)();
+		exit(0);
+	}
+
+	if(strcmp(argv[1], "--version") == 0) {
+		printf("%s %s\n", self, VERSION);
+		exit(0);
+	}
+}
+
 /* read entire file into memory */
-int readfile(void) {
-	int got = fread(program, 1, BUFSIZE - 1, input_file);
-	if(verbose) fprintf(stderr, "Read %d bytes.\n", got);
+void readfile(void) {
+	filelen = fread(program, 1, BUFSIZE - 1, input_file);
+	if(verbose) fprintf(stderr, "Read %d bytes.\n", filelen);
 	if(!feof(input_file))
 		fprintf(stderr, "Warning: file is >64KB, way too big for a BASIC program.\n");
-	else if(got > MAX_PROG_SIZE)
-		fprintf(stderr, "Warning: file is %d bytes, suspiciously large for a BASIC program.\n", got);
+	else if(filelen > MAX_PROG_SIZE)
+		fprintf(stderr, "Warning: file is %d bytes, suspiciously large for a BASIC program.\n", filelen);
 	fclose(input_file);
-	if(got < MIN_PROG_SIZE)
+	if(filelen < MIN_PROG_SIZE)
 		die("File too short to be a BASIC program (truncated?)\n");
-	return got;
+}
+
+int writefile(void) {
+	int outbytes;
+
+	outbytes = fwrite(program, 1, filelen, output_file);
+	fclose(output_file);
+	if(verbose) fprintf(stderr, "Wrote %d bytes.\n", outbytes);
+	return outbytes;
 }
 
 /* get a 16-bit value from the file, in 6502 LSB/MSB order. */
@@ -76,6 +102,8 @@ void parse_header(void) {
 	vvstart = vvtp - TBL_OFFSET;
 	code_end = starp - TBL_OFFSET;
 
+	if(lomem) die("This doesn't look like an Atari BASIC program (no $0000 signature).");
+
 	if(filelen < code_end) {
 		fprintf(stderr, "Warning: file is truncated: %d bytes, should be %d.\n", filelen, code_end);
 	}
@@ -111,9 +139,9 @@ void move_code(int offset) {
 	stmtab += offset;
 	stmcur += offset;
 	starp += offset;
+	filelen += offset;
 	update_header();
 	parse_header();
-	filelen += offset;
 }
 
 void adjust_vntable_size(int oldsize, int newsize) {
@@ -127,6 +155,53 @@ void adjust_vntable_size(int oldsize, int newsize) {
 	}
 }
 
+/* return true if the variable name table is OK */
+int vntable_ok(void) {
+	int vp, bad;
+
+	if(vntp == vntd) {
+		if(verbose) fprintf(stderr, "No variables.\n");
+		return 1;
+	}
+
+	/* first pass: bad = 1 if all the bytes in the table have the same
+		value, no matter what it is. */
+	vp = vnstart + 1;
+	bad = 1;
+	while(vp < vvstart - 1) {
+		if(program[vp] != program[vnstart]) {
+			bad = 0;
+			break;
+		}
+		vp++;
+	}
+	if(bad) return 0;
+
+	/* 2nd pass: bad = 1 if there's any invalid character in the table. */
+	vp = vnstart;
+	while(vp < vvstart) {
+		unsigned char c = program[vp];
+
+		/* treat a null byte as end-of-table, ignore any junk between it and VNTP. */
+		if(c == 0) break;
+
+		vp++;
+
+		/* inverse $ or ( is OK */
+		if(c == 0xa4 || c == 0xa8) continue;
+
+		/* numbers and letters are allowed, inverse or normal. */
+		c &= 0x7f;
+		if(c >= 0x30 && c <= 0x39) continue;
+		if(c >= 0x41 && c <= 0x5a) continue;
+
+		bad++;
+		break;
+	}
+
+	return !bad;
+}
+
 void invalid_args(const char *arg) {
 	fprintf(stderr, "%s: Invalid argument '%s'.\n\n", self, arg);
 	exit(1);