[FFmpeg-cvslog] r18572 - trunk/libavcodec/xan.c
reimar
subversion
Fri Apr 17 19:46:10 CEST 2009
Author: reimar
Date: Fri Apr 17 19:46:10 2009
New Revision: 18572
Log:
Replace bytecopy with the equivalent but faster av_memcpy_backptr.
Ca. 10% faster xan_unpack on x86_64 decoding of SC_32-part.MVE
Modified:
trunk/libavcodec/xan.c
Modified: trunk/libavcodec/xan.c
==============================================================================
--- trunk/libavcodec/xan.c Fri Apr 17 19:42:41 2009 (r18571)
+++ trunk/libavcodec/xan.c Fri Apr 17 19:46:10 2009 (r18572)
@@ -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(AVCod
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 c
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 *de
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 *de
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 *de
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 {
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