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Replace bytecopy with the equivalent but faster av_memcpy_backptr. 

Ca. 10% faster xan_unpack on x86_64 decoding of SC_32-part.MVE

Originally committed as revision 18572 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger 2009-04-17 17:46:10 +00:00
parent 4eec260642
commit 9126aea528
1 changed files with 12 additions and 18 deletions
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30
libavcodec/xan.c
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@ -35,6 +35,8 @@
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
// for av_memcpy_backptr
#include "libavutil/lzo.h"
typedef struct XanContext {
@ -76,26 +78,13 @@ static av_cold int xan_decode_init(AVCodecContext *avctx)
s->buffer1_size = avctx->width * avctx->height;
s->buffer1 = av_malloc(s->buffer1_size);
s->buffer2_size = avctx->width * avctx->height;
s->buffer2 = av_malloc(s->buffer2_size);
s->buffer2 = av_malloc(s->buffer2_size + 12);
if (!s->buffer1 || !s->buffer2)
return -1;
return 0;
}
/* This function is used in lieu of memcpy(). This decoder cannot use
* memcpy because the memory locations often overlap and
* memcpy doesn't like that; it's not uncommon, for example, for
* dest = src+1, to turn byte A into pattern AAAAAAAA.
* This was originally repz movsb in Intel x86 ASM. */
static inline void bytecopy(unsigned char *dest, const unsigned char *src, int count)
{
int i;
for (i = 0; i < count; i++)
dest[i] = src[i];
}
static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
int dest_len)
{
@ -130,6 +119,11 @@ static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
return 0;
}
/**
* unpack simple compression
*
* @param dest destination buffer of dest_len, must be sufficiently padded for av_memcpy_backptr
*/
static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
{
unsigned char opcode;
@ -153,7 +147,7 @@ static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_l
size = ((opcode & 0x1c) >> 2) + 3;
if (dest + size > dest_end)
return;
bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
av_memcpy_backptr(dest, ((opcode & 0x60) << 3) + offset + 1, size);
dest += size;
} else if ( (opcode & 0x40) == 0 ) {
@ -169,7 +163,7 @@ static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_l
size = (opcode & 0x3f) + 4;
if (dest + size > dest_end)
return;
bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
av_memcpy_backptr(dest, ((byte1 & 0x3f) << 8) + byte2 + 1, size);
dest += size;
} else if ( (opcode & 0x20) == 0 ) {
@ -186,8 +180,8 @@ static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_l
size = byte3 + 5 + ((opcode & 0xc) << 6);
if (dest + size > dest_end)
return;
bytecopy (dest,
dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
av_memcpy_backptr(dest,
(((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2,
size);
dest += size;
} else {