I am working on optimizing "PMP Mod 1.01" for AVC decoder, and I noticed following functions[1] in PMP Mod 1.01\libavcodec\h264idct.c are cpu consuming. The only optimization I can find now is to expand loop (e.g. expand "for(i=1;i<8;i++) {foo(i)}" to "foo(1);foo(2);...;foo(7)" and hope gcc can pipleline them more) which *may* improve +1fps decoding. I also noticed there was a MMX optimization version [2] in original ffmpeg\libavcodec\i386\h264dsp_mmx.c.
My questions is: Is it possible to use VFPU to optimize AVC IDCT job as well as mmx does it on i386 platform? I mean I can not find detailed VFPU instruction manual and samples.:(
Thank you!
Reference:
1. PMP Mod 1.01\libavcodec\h264idct.c
Code: Select all
#include "dsputil.h"
static always_inline void idct_internal(uint8_t *dst, DCTELEM *block, int stride, int block_stride, int shift, int add){
int i;
uint8_t *cm = cropTbl + MAX_NEG_CROP;
block[0] += 1<<(shift-1);
for(i=0; i<4; i++){
const int z0= block[0 + block_stride*i] + block[2 + block_stride*i];
const int z1= block[0 + block_stride*i] - block[2 + block_stride*i];
const int z2= (block[1 + block_stride*i]>>1) - block[3 + block_stride*i];
const int z3= block[1 + block_stride*i] + (block[3 + block_stride*i]>>1);
block[0 + block_stride*i]= z0 + z3;
block[1 + block_stride*i]= z1 + z2;
block[2 + block_stride*i]= z1 - z2;
block[3 + block_stride*i]= z0 - z3;
}
for(i=0; i<4; i++){
const int z0= block[i + block_stride*0] + block[i + block_stride*2];
const int z1= block[i + block_stride*0] - block[i + block_stride*2];
const int z2= (block[i + block_stride*1]>>1) - block[i + block_stride*3];
const int z3= block[i + block_stride*1] + (block[i + block_stride*3]>>1);
dst[i + 0*stride]= cm[ add*dst[i + 0*stride] + ((z0 + z3) >> shift) ];
dst[i + 1*stride]= cm[ add*dst[i + 1*stride] + ((z1 + z2) >> shift) ];
dst[i + 2*stride]= cm[ add*dst[i + 2*stride] + ((z1 - z2) >> shift) ];
dst[i + 3*stride]= cm[ add*dst[i + 3*stride] + ((z0 - z3) >> shift) ];
}
}
void ff_h264_idct_add_c(uint8_t *dst, DCTELEM *block, int stride){
idct_internal(dst, block, stride, 4, 6, 1);
}
void ff_h264_lowres_idct_add_c(uint8_t *dst, int stride, DCTELEM *block){
idct_internal(dst, block, stride, 8, 3, 1);
}
void ff_h264_lowres_idct_put_c(uint8_t *dst, int stride, DCTELEM *block){
idct_internal(dst, block, stride, 8, 3, 0);
}
void ff_h264_idct8_add_c(uint8_t *dst, DCTELEM *block, int stride){
int i;
DCTELEM (*src)[8] = (DCTELEM(*)[8])block;
uint8_t *cm = cropTbl + MAX_NEG_CROP;
block[0] += 32;
for( i = 0; i < 8; i++ )
{
const int a0 = src[i][0] + src[i][4];
const int a2 = src[i][0] - src[i][4];
const int a4 = (src[i][2]>>1) - src[i][6];
const int a6 = (src[i][6]>>1) + src[i][2];
const int b0 = a0 + a6;
const int b2 = a2 + a4;
const int b4 = a2 - a4;
const int b6 = a0 - a6;
const int a1 = -src[i][3] + src[i][5] - src[i][7] - (src[i][7]>>1);
const int a3 = src[i][1] + src[i][7] - src[i][3] - (src[i][3]>>1);
const int a5 = -src[i][1] + src[i][7] + src[i][5] + (src[i][5]>>1);
const int a7 = src[i][3] + src[i][5] + src[i][1] + (src[i][1]>>1);
const int b1 = (a7>>2) + a1;
const int b3 = a3 + (a5>>2);
const int b5 = (a3>>2) - a5;
const int b7 = a7 - (a1>>2);
src[i][0] = b0 + b7;
src[i][7] = b0 - b7;
src[i][1] = b2 + b5;
src[i][6] = b2 - b5;
src[i][2] = b4 + b3;
src[i][5] = b4 - b3;
src[i][3] = b6 + b1;
src[i][4] = b6 - b1;
}
for( i = 0; i < 8; i++ )
{
const int a0 = src[0][i] + src[4][i];
const int a2 = src[0][i] - src[4][i];
const int a4 = (src[2][i]>>1) - src[6][i];
const int a6 = (src[6][i]>>1) + src[2][i];
const int b0 = a0 + a6;
const int b2 = a2 + a4;
const int b4 = a2 - a4;
const int b6 = a0 - a6;
const int a1 = -src[3][i] + src[5][i] - src[7][i] - (src[7][i]>>1);
const int a3 = src[1][i] + src[7][i] - src[3][i] - (src[3][i]>>1);
const int a5 = -src[1][i] + src[7][i] + src[5][i] + (src[5][i]>>1);
const int a7 = src[3][i] + src[5][i] + src[1][i] + (src[1][i]>>1);
const int b1 = (a7>>2) + a1;
const int b3 = a3 + (a5>>2);
const int b5 = (a3>>2) - a5;
const int b7 = a7 - (a1>>2);
dst[i + 0*stride] = cm[ dst[i + 0*stride] + ((b0 + b7) >> 6) ];
dst[i + 1*stride] = cm[ dst[i + 1*stride] + ((b2 + b5) >> 6) ];
dst[i + 2*stride] = cm[ dst[i + 2*stride] + ((b4 + b3) >> 6) ];
dst[i + 3*stride] = cm[ dst[i + 3*stride] + ((b6 + b1) >> 6) ];
dst[i + 4*stride] = cm[ dst[i + 4*stride] + ((b6 - b1) >> 6) ];
dst[i + 5*stride] = cm[ dst[i + 5*stride] + ((b4 - b3) >> 6) ];
dst[i + 6*stride] = cm[ dst[i + 6*stride] + ((b2 - b5) >> 6) ];
dst[i + 7*stride] = cm[ dst[i + 7*stride] + ((b0 - b7) >> 6) ];
}
}Code: Select all
void ff_h264_idct_add_mmx2(uint8_t *dst, int16_t *block, int stride)
{
/* Load dct coeffs */
asm volatile(
"movq (%0), %%mm0 \n\t"
"movq 8(%0), %%mm1 \n\t"
"movq 16(%0), %%mm2 \n\t"
"movq 24(%0), %%mm3 \n\t"
:: "r"(block) );
asm volatile(
/* mm1=s02+s13 mm2=s02-s13 mm4=d02+d13 mm0=d02-d13 */
IDCT4_1D( %%mm2, %%mm1, %%mm0, %%mm3, %%mm4 )
"movq %0, %%mm6 \n\t"
/* in: 1,4,0,2 out: 1,2,3,0 */
TRANSPOSE4( %%mm3, %%mm1, %%mm0, %%mm2, %%mm4 )
"paddw %%mm6, %%mm3 \n\t"
/* mm2=s02+s13 mm3=s02-s13 mm4=d02+d13 mm1=d02-d13 */
IDCT4_1D( %%mm4, %%mm2, %%mm3, %%mm0, %%mm1 )
"pxor %%mm7, %%mm7 \n\t"
:: "m"(ff_pw_32));
asm volatile(
STORE_DIFF_4P( %%mm0, %%mm1, %%mm7)
"add %1, %0 \n\t"
STORE_DIFF_4P( %%mm2, %%mm1, %%mm7)
"add %1, %0 \n\t"
STORE_DIFF_4P( %%mm3, %%mm1, %%mm7)
"add %1, %0 \n\t"
STORE_DIFF_4P( %%mm4, %%mm1, %%mm7)
: "+r"(dst)
: "r" ((long)stride)
);
}
(transposed of C)
