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Optimize ff_snow_horizontal_compose97i.

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this makes the 9/7 C wavelet at the decoder side 22% faster.
The old code is changed to match the new in terms of the order of operations
(which also makes it sligtly faster)

Originally committed as revision 21132 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2010-01-11 02:52:50 +00:00
parent 233a8b3d6b
commit 2c8077621b
1 changed files with 30 additions and 4 deletions
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34
libavcodec/snow.c
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@ -1120,10 +1120,36 @@ void ff_snow_horizontal_compose97i(IDWTELEM *b, int width){
IDWTELEM temp[width];
const int w2= (width+1)>>1;
inv_lift (temp , b , b +w2, 1, 1, 1, width, W_DM, W_DO, W_DS, 0, 1);
inv_lift (temp+w2, b +w2, temp , 1, 1, 1, width, W_CM, W_CO, W_CS, 1, 1);
inv_liftS(b , temp , temp+w2, 2, 1, 1, width, W_BM, W_BO, W_BS, 0, 1);
inv_lift (b+1 , temp+w2, b , 2, 1, 2, width, W_AM, W_AO, W_AS, 1, 0);
#if 0 //maybe more understadable but slower
inv_lift (temp , b , b +w2, 2, 1, 1, width, W_DM, W_DO, W_DS, 0, 1);
inv_lift (temp+1 , b +w2, temp , 2, 1, 2, width, W_CM, W_CO, W_CS, 1, 1);
inv_liftS(b , temp , temp+1 , 2, 2, 2, width, W_BM, W_BO, W_BS, 0, 1);
inv_lift (b+1 , temp+1 , b , 2, 2, 2, width, W_AM, W_AO, W_AS, 1, 0);
#else
int x;
temp[0] = b[0] - ((3*b[w2]+2)>>2);
for(x=1; x<(width>>1); x++){
temp[2*x ] = b[x ] - ((3*(b [x+w2-1] + b[x+w2])+4)>>3);
temp[2*x-1] = b[x+w2-1] - temp[2*x-2] - temp[2*x];
}
if(width&1){
temp[2*x ] = b[x ] - ((3*b [x+w2-1]+2)>>2);
temp[2*x-1] = b[x+w2-1] - temp[2*x-2] - temp[2*x];
}else
temp[2*x-1] = b[x+w2-1] - 2*temp[2*x-2];
b[0] = temp[0] + ((2*temp[0] + temp[1]+4)>>3);
for(x=2; x<width-1; x+=2){
b[x ] = temp[x ] + ((4*temp[x ] + temp[x-1] + temp[x+1]+8)>>4);
b[x-1] = temp[x-1] + ((3*(b [x-2] + b [x ] ))>>1);
}
if(width&1){
b[x ] = temp[x ] + ((2*temp[x ] + temp[x-1]+4)>>3);
b[x-1] = temp[x-1] + ((3*(b [x-2] + b [x ] ))>>1);
}else
b[x-1] = temp[x-1] + 3*b [x-2];
#endif
}
static void vertical_compose97iH0(IDWTELEM *b0, IDWTELEM *b1, IDWTELEM *b2, int width){