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avcodec/xbmenc: Avoid snprintf() for data->hex conversion 

Use a small LUT instead. Improves performance.

Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-03-06 01:40:23 +01:00
parent 357e339898
commit 878f8cabe8
1 changed files with 15 additions and 6 deletions
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21
libavcodec/xbmenc.c
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@ -20,11 +20,9 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/reverse.h"
#include "avcodec.h"
#include "codec_internal.h"
#include "encode.h"
#include "mathops.h"
#define ANSI_MIN_READLINE 509
@ -57,14 +55,25 @@ static int xbm_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
buf += snprintf(buf, 39, "static unsigned char image_bits[] = {\n");
for (i = 0, l = lineout; i < avctx->height; i++) {
for (j = 0; j < linesize; j++) {
buf += snprintf(buf, 6, " 0x%02X", ff_reverse[*ptr++]);
// 0..15 bitreversed as chars
static const char lut[] = {
'0', '8', '4', 'C', '2', 'A', '6', 'E',
'1', '9', '5', 'D', '3', 'B', '7', 'F'
};
buf[0] = ' ';
buf[1] = '0';
buf[2] = 'x';
buf[3] = lut[*ptr & 0xF];
buf[4] = lut[*ptr >> 4];
buf += 5;
ptr++;
if (--commas <= 0) {
buf += snprintf(buf, 2, "\n");
*buf++ = '\n';
break;
}
buf += snprintf(buf, 2, ",");
*buf++ = ',';
if (--l <= 0) {
buf += snprintf(buf, 2, "\n");
*buf++ = '\n';
l = lineout;
}
}