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/* See LICENSE file for copyright and license details. */
#include <arpa/inet.h>
#include <errno.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "arg.h"
#include "util.h"
static void
usage(void)
{
fprintf(stderr, "usage: %s [-b colour]\n", argv0);
exit(1);
}
int
main(int argc, char *argv[])
{
size_t rowlen, rowoutlen;
uint64_t a;
uint32_t width, height, i, j, k, l;
uint16_t *row, mask[3] = { 0xffff, 0xffff, 0xffff };
uint8_t *rowout;
/* arguments */
ARGBEGIN {
case 'b':
if (parse_mask(EARGF(usage()), mask)) {
usage();
}
break;
default:
usage();
} ARGEND
if (argc) {
usage();
}
/* prepare */
ff_read_header(&width, &height);
row = ereallocarray(NULL, width, (sizeof("RGBA") - 1) * sizeof(uint16_t));
rowout = ereallocarray(NULL, width, (sizeof("RGB") - 1) * sizeof(uint8_t));
rowlen = width * (sizeof("RGBA") - 1);
rowoutlen = width * (sizeof("RGB") - 1);
/* write data */
printf("P6\n%" PRIu32 " %" PRIu32 "\n255\n", width, height);
for (i = 0; i < height; ++i) {
if (fread(row, sizeof(uint16_t), rowlen, stdin) != rowlen) {
if (ferror(stdin)) {
fprintf(stderr, "%s: fread: %s\n", argv0,
strerror(errno));
} else {
fprintf(stderr, "%s: unexpected end of file\n",
argv0);
}
return 1;
}
for (j = 0, k = 0; j < rowlen; j += 4, k += 3) {
a = ntohs(row[j + 3]);
for (l = 0; l < 3; l++) {
/* alpha blending and 8-bit-reduction */
rowout[k + l] = (a * ntohs(row[j + l]) +
(UINT16_MAX - a) * mask[l]) /
(UINT16_MAX *
(UINT16_MAX / UINT8_MAX));
}
}
if (fwrite(rowout, sizeof(uint8_t), rowoutlen, stdout) != rowoutlen) {
fprintf(stderr, "%s: fwrite: %s\n", argv0, strerror(errno));
return 1;
}
}
return fshut(stdout, "<stdout>");
}
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