+int parserange(unsigned frames, char *str, unsigned char *bits)
+{
+ unsigned long start, end;
+ unsigned int i;
+ char *endptr;
+
+ start = strtoul(str, &endptr, 0);
+ if (start >= frames) {
+ tool_err(-1, "frame %lu out of range.", start);
+ return -1;
+ }
+
+ if (endptr == str) {
+ tool_err(-1, "invalid frame range: %s.", str);
+ return -1;
+ }
+
+ switch (*endptr) {
+ case '\0':
+ end = start;
+ break;
+ case '-':
+ end = strtoul(endptr+1, &endptr, 0);
+ if (end >= frames) {
+ tool_err(-1, "frame %lu out of range.", end);
+ return -1;
+ }
+
+ if (endptr == str)
+ end = frames - 1;
+ break;
+ default:
+ tool_err(-1, "invalid frame range: %s.", str);
+ return -1;
+ }
+
+ if (end < start) {
+ tool_err(-1, "invalid frame range: %s.", str);
+ return -1;
+ }
+
+ for (i = start; i <= end; i++) {
+ bits[i / CHAR_BIT] |= 1 << (i % CHAR_BIT);
+ }
+
+ return 0;
+}
+
+int outpng(unsigned int frameno,
+ unsigned char **framedata, unsigned char **mask,
+ unsigned int width, unsigned int height,
+ struct lbx_colour palette[static 256])
+{
+ char name[strlen(outname) + sizeof ".65535.png"];
+ FILE *of;
+ int rc;
+
+ assert(frameno < 65536);
+ snprintf(name, sizeof name, "%s.%03d.png", outname, frameno);
+
+ of = fopen(name, "wb");
+ if (!of) {
+ tool_err(0, "failed to open %s", name);
+ return -1;
+ }
+
+ rc = img_output_png(of, name, width, height, framedata, mask, palette);
+ if (rc < 0) {
+ fclose(of);
+ return -1;
+ }
+
+ if (fclose(of) == EOF) {
+ tool_err(0, "error writing %s", name);
+ return -1;
+ }
+
+ if (verbose)
+ printf("wrote %s\n", name);
+
+ return 0;
+}
+
+static int loadoverride(FILE *f, struct lbx_colour palette[static 256])
+{
+ struct lbx_image *overimg = lbx_img_open(f, &lbx_default_fops, NULL);
+ struct lbx_imginfo info;
+
+ if (!overimg) {
+ tool_err(-1, "failed to open override image: %s", lbx_errmsg());
+ return -1;
+ }
+ lbx_img_getinfo(overimg, &info);
+
+ if (!info.palettesz) {
+ tool_err(-1, "override image has no palette.");
+ lbx_img_close(overimg);
+ return -1;
+ }
+
+ if (lbx_img_getpalette(overimg, palette) == -1) {
+ tool_err(-1, "error reading override palette: %s", lbx_errmsg());
+ lbx_img_close(overimg);
+ return -1;
+ }
+
+ lbx_img_close(overimg);
+ return 0;
+}
+
+static int loadpalette(struct lbx_image *img, struct lbx_imginfo *info,
+ FILE *palf, FILE *override,
+ struct lbx_colour palette[static 256])
+{
+ int i;
+
+ /* For sanity. */
+ if (!palf && !info->palettesz && !override) {
+ tool_err(-1, "no palette available.");
+ return -1;
+ }
+
+ /* Default the palette to a wonderful pink. */
+ for (i = 0; i < 256; i++) {
+ palette[i] = (struct lbx_colour){0xff, 0x00, 0xff};
+ }
+
+ /* Read the external palette, if any. */
+ if (palf && lbx_img_loadpalette(palf, &lbx_default_fops, palette) != 0) {
+ tool_err(-1, "error reading external palette: %s", lbx_errmsg());
+ return -1;
+ }
+
+ /* Read the embedded palette, if any. */
+ if (info->palettesz && lbx_img_getpalette(img, palette) == -1) {
+ tool_err(-1, "error reading embedded palette: %s", lbx_errmsg());
+ return -1;
+ }
+
+ /* Read the override palette, if any. */
+ if (override && loadoverride(override, palette) == -1) {
+ return -1;
+ }
+
+ return 0;
+}
+
+int decode(struct lbx_image *img, FILE *palf, FILE *override, char **argv)
+{
+ unsigned char *framebits;
+ struct lbx_colour palette[256];
+ struct lbx_imginfo info;
+ int extracted = 0;
+ unsigned int i;
+
+ lbx_img_getinfo(img, &info);
+
+ framebits = calloc(1, img->frames / CHAR_BIT + 1);
+ if (!framebits) {
+ return EXIT_FAILURE;
+ }
+
+ /* Figure out what images we're extracting. */
+ if (!argv[0]) {
+ /* extract all images by default. */
+ memset(framebits, -1, img->frames / CHAR_BIT + 1);
+ } else {
+ for (i = 0; argv[i]; i++) {
+ parserange(img->frames, argv[i], framebits);
+ }
+ }
+
+ if (usepalette) {
+ if (loadpalette(img, &info, palf, override, palette) == -1) {
+ goto err;
+ }
+ }
+
+ /* Extract the images, in order. */
+ for (i = 0; i < img->frames; i++) {
+ unsigned char **data;
+ unsigned char **mask;
+
+ if (!(framebits[i / CHAR_BIT] & (1 << (i % CHAR_BIT))))
+ continue;
+
+ data = lbx_img_getframe(img, i);
+ if (!data) {
+ tool_err(-1, "error in frame %u: %s", i, lbx_errmsg());
+ continue;
+ }
+
+ mask = lbx_img_getmask(img);
+
+ if (!outpng(i, data, mask, img->width, img->height,
+ usepalette ? palette : NULL)) {
+ extracted = 1;
+ }
+ }
+
+ if (!extracted) {
+ tool_err(-1, "no frames extracted.");
+ goto err;
+ }
+
+ free(framebits);
+ return EXIT_SUCCESS;
+err:
+ free(framebits);
+ return EXIT_FAILURE;
+}
+