[FFmpeg-cvslog] sgidec: make compiler optimize away memcpy call in inner loop.
Reimar Döffinger
git at videolan.org
Mon Jan 9 11:03:59 CET 2012
ffmpeg | branch: master | Reimar Döffinger <Reimar.Doeffinger at gmx.de> | Sun Jan 8 12:19:48 2012 +0100| [4231bbbf4c54c22fbda6832002675b43f24d3802] | committer: Reimar Döffinger
sgidec: make compiler optimize away memcpy call in inner loop.
Using an always_inline function makes the memcpy length a constant,
any reasonable compiler will replace it by a single mov instruction
without us having to duplicate the actual code.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4231bbbf4c54c22fbda6832002675b43f24d3802
---
libavcodec/sgidec.c | 38 +++++++++++++++++++++++++-------------
1 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/libavcodec/sgidec.c b/libavcodec/sgidec.c
index ae05d83..98327a8 100644
--- a/libavcodec/sgidec.c
+++ b/libavcodec/sgidec.c
@@ -20,6 +20,7 @@
*/
#include "libavutil/imgutils.h"
+#include "libavutil/avassert.h"
#include "avcodec.h"
#include "bytestream.h"
#include "sgi.h"
@@ -113,6 +114,25 @@ static int read_rle_sgi(unsigned char* out_buf, const uint8_t *in_buf,
return 0;
}
+static av_always_inline void copy_loop(uint8_t *out_buf, const uint8_t *in_buf,
+ unsigned offset, unsigned bytes_per_channel,
+ SgiState *s)
+{
+ int x, y, z;
+ for (y = s->height - 1; y >= 0; y--) {
+ uint8_t *line = out_buf + (y * s->linesize);
+ for (x = s->width; x > 0; x--) {
+ const uint8_t *ptr = in_buf;
+ in_buf += bytes_per_channel;
+ for(z = 0; z < s->depth; z ++) {
+ memcpy(line, ptr, bytes_per_channel);
+ line += bytes_per_channel;
+ ptr += offset;
+ }
+ }
+ }
+}
+
/**
* Read an uncompressed SGI image.
* @param out_buf output buffer
@@ -125,8 +145,6 @@ static int read_rle_sgi(unsigned char* out_buf, const uint8_t *in_buf,
static int read_uncompressed_sgi(unsigned char* out_buf, uint8_t* out_end,
const uint8_t *in_buf, const uint8_t *in_end, SgiState* s)
{
- int x, y, z;
- const uint8_t *ptr;
unsigned int offset = s->height * s->width * s->bytes_per_channel;
/* Test buffer size. */
@@ -134,17 +152,11 @@ static int read_uncompressed_sgi(unsigned char* out_buf, uint8_t* out_end,
return -1;
}
- for (y = s->height - 1; y >= 0; y--) {
- out_end = out_buf + (y * s->linesize);
- for (x = s->width; x > 0; x--) {
- ptr = in_buf;
- in_buf += s->bytes_per_channel;
- for(z = 0; z < s->depth; z ++) {
- memcpy(out_end, ptr, s->bytes_per_channel);
- out_end += s->bytes_per_channel;
- ptr += offset;
- }
- }
+ if (s->bytes_per_channel == 2) {
+ copy_loop(out_buf, in_buf, offset, 2, s);
+ } else {
+ av_assert1(s->bytes_per_channel == 1);
+ copy_loop(out_buf, in_buf, offset, 1, s);
}
return 0;
}
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