1 files changed, 90 insertions, 0 deletions
diff --git a/ff2png.c b/ff2png.c
new file mode 100644
index 0000000..4cbbf22
--- /dev/null
+++ b/ff2png.c
@@ -0,0 +1,90 @@
+/* See LICENSE file for copyright and license details. */
+#include <endian.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <png.h>
+
+#include "arg.h"
+
+char *argv0;
+
+#define HEADER_FORMAT "farbfeld########"
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: %s\n", argv0);
+	exit(1);
+}
+
+int
+main(int argc, char *argv[])
+{
+	png_structp png_struct_p;
+	png_infop png_info_p;
+	uint8_t hdr[17], *png_row;
+	uint16_t tmp16;
+	png_uint_32 width, height, i;
+	png_size_t png_row_len, j;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc)
+		usage();
+
+	/* header */
+	if (fread(hdr, 1, strlen(HEADER_FORMAT), stdin) != strlen(HEADER_FORMAT)) {
+		fprintf(stderr, "failed to read from stdin or input too short\n");
+		return 1;
+	}
+	if (memcmp("farbfeld", hdr, strlen("farbfeld"))) {
+		fprintf(stderr, "invalid magic in header\n");
+		return 1;
+	}
+	width = be32toh((hdr[9] << 0) | (hdr[10] << 8) | (hdr[11] << 16) | (hdr[12] << 24));
+	height = be32toh((hdr[13] << 0) | (hdr[14] << 8) | (hdr[15] << 16) | (hdr[16] << 24));
+
+	/* load png */
+	png_struct_p = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	png_info_p = png_create_info_struct(png_struct_p);
+
+	if (!png_struct_p || !png_info_p || setjmp(png_jmpbuf(png_struct_p))) {
+		fprintf(stderr, "failed to initialize libpng\n");
+		return 1;
+	}
+	png_init_io(png_struct_p, stdout);
+	png_set_IHDR(png_struct_p, png_info_p, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
+		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+	png_write_info(png_struct_p, png_info_p);
+
+	/* write rows */
+	png_row_len = strlen("RGBA") * width * sizeof(uint8_t);
+	png_row = malloc(png_row_len);
+	if (!png_row) {
+		fprintf(stderr, "failed to allocate row-buffer\n");
+		return 1;
+	}
+
+	for (i = 0; i < height; ++i) {
+		for (j = 0; j < png_row_len; ++j) {
+			if (fread(&tmp16, 1, sizeof(uint16_t), stdin) != sizeof(uint16_t)) {
+				fprintf(stderr, "unexpected EOF or row-skew\n");
+				return 1;
+			}
+			png_row[j] = be16toh(tmp16) / (1 << 8);
+		}
+		png_write_row(png_struct_p, png_row);
+	}
+	png_write_end(png_struct_p, NULL);
+
+	/* clean up */
+	png_free_data(png_struct_p, png_info_p, PNG_FREE_ALL, -1);
+	png_destroy_write_struct(&png_struct_p, NULL);
+	free(png_row);
+	return 0;
+}