simple_idct.c
来自「从FFMPEG转换而来的H264解码程序,VC下编译..」· C语言 代码 · 共 248 行
C
248 行
/*****************************************************************************
*
* XVID MPEG-4 VIDEO CODEC
* - Inverse DCT (More precise version) -
*
* Copyright (c) 2001 Michael Niedermayer <michaelni@gmx.at>
*
* Originally distributed under the GNU LGPL License (ffmpeg).
* It is licensed under the GNU GPL for the XviD tree.
*
* This program is free software ; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation ; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY ; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program ; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: simple_idct.c,v 1.5 2004/04/05 20:36:36 edgomez Exp $
*
****************************************************************************/
/*
based upon some outcommented c code from mpeg2dec (idct_mmx.c
written by Aaron Holtzman <aholtzma@ess.engr.uvic.ca>)
*/
#include "../portab.h"
#include "idct.h"
#if 0
#define W1 2841 /* 2048*sqrt (2)*cos (1*pi/16) */
#define W2 2676 /* 2048*sqrt (2)*cos (2*pi/16) */
#define W3 2408 /* 2048*sqrt (2)*cos (3*pi/16) */
#define W4 2048 /* 2048*sqrt (2)*cos (4*pi/16) */
#define W5 1609 /* 2048*sqrt (2)*cos (5*pi/16) */
#define W6 1108 /* 2048*sqrt (2)*cos (6*pi/16) */
#define W7 565 /* 2048*sqrt (2)*cos (7*pi/16) */
#define ROW_SHIFT 8
#define COL_SHIFT 17
#else
#define W1 22725 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define W2 21407 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define W3 19266 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define W4 16383 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define W5 12873 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define W6 8867 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define W7 4520 /* cos(i*M_PI/16)*sqrt(2)*(1<<14) + 0.5 */
#define ROW_SHIFT 11
#define COL_SHIFT 20 /* 6 */
#endif
/*
PPC mac operation. Causes compile problems on newer ppc targets
Was originally: #if defined(ARCH_IS_PPC)
*/
#if 0
/* signed 16x16 -> 32 multiply add accumulate */
#define MAC16(rt, ra, rb) \
asm ("maclhw %0, %2, %3" : "=r" (rt) : "0" (rt), "r" (ra), "r" (rb));
/* signed 16x16 -> 32 multiply */
#define MUL16(rt, ra, rb) \
asm ("mullhw %0, %1, %2" : "=r" (rt) : "r" (ra), "r" (rb));
#else
/* signed 16x16 -> 32 multiply add accumulate */
#define MAC16(rt, ra, rb) rt += (ra) * (rb)
/* signed 16x16 -> 32 multiply */
#define MUL16(rt, ra, rb) rt = (ra) * (rb)
#endif
static __inline void idctRowCondDC (int16_t * const row)
{
int a0, a1, a2, a3, b0, b1, b2, b3;
#ifdef FAST_64BIT
uint64_t temp;
#else
uint32_t temp;
#endif
#ifdef FAST_64BIT
#ifdef ARCH_IS_BIG_ENDIAN
#define ROW0_MASK 0xffff000000000000LL
#else
#define ROW0_MASK 0xffffLL
#endif
if ( ((((uint64_t *)row)[0] & ~ROW0_MASK) |
((uint64_t *)row)[1]) == 0) {
temp = (row[0] << 3) & 0xffff;
temp += temp << 16;
temp += temp << 32;
((uint64_t *)row)[0] = temp;
((uint64_t *)row)[1] = temp;
return;
}
#else
if (!(((uint32_t*)row)[1] |
((uint32_t*)row)[2] |
((uint32_t*)row)[3] |
row[1])) {
temp = (row[0] << 3) & 0xffff;
temp += temp << 16;
((uint32_t*)row)[0]=((uint32_t*)row)[1] =
((uint32_t*)row)[2]=((uint32_t*)row)[3] = temp;
return;
}
#endif
a0 = (W4 * row[0]) + (1 << (ROW_SHIFT - 1));
a1 = a0;
a2 = a0;
a3 = a0;
/* no need to optimize : gcc does it */
a0 += W2 * row[2];
a1 += W6 * row[2];
a2 -= W6 * row[2];
a3 -= W2 * row[2];
MUL16(b0, W1, row[1]);
MAC16(b0, W3, row[3]);
MUL16(b1, W3, row[1]);
MAC16(b1, -W7, row[3]);
MUL16(b2, W5, row[1]);
MAC16(b2, -W1, row[3]);
MUL16(b3, W7, row[1]);
MAC16(b3, -W5, row[3]);
#ifdef FAST_64BIT
temp = ((uint64_t*)row)[1];
#else
temp = ((uint32_t*)row)[2] | ((uint32_t*)row)[3];
#endif
if (temp != 0) {
a0 += W4*row[4] + W6*row[6];
a1 += - W4*row[4] - W2*row[6];
a2 += - W4*row[4] + W2*row[6];
a3 += W4*row[4] - W6*row[6];
MAC16(b0, W5, row[5]);
MAC16(b0, W7, row[7]);
MAC16(b1, -W1, row[5]);
MAC16(b1, -W5, row[7]);
MAC16(b2, W7, row[5]);
MAC16(b2, W3, row[7]);
MAC16(b3, W3, row[5]);
MAC16(b3, -W1, row[7]);
}
row[0] = (a0 + b0) >> ROW_SHIFT;
row[7] = (a0 - b0) >> ROW_SHIFT;
row[1] = (a1 + b1) >> ROW_SHIFT;
row[6] = (a1 - b1) >> ROW_SHIFT;
row[2] = (a2 + b2) >> ROW_SHIFT;
row[5] = (a2 - b2) >> ROW_SHIFT;
row[3] = (a3 + b3) >> ROW_SHIFT;
row[4] = (a3 - b3) >> ROW_SHIFT;
}
static __inline void idctSparseCol (int16_t * const col)
{
int a0, a1, a2, a3, b0, b1, b2, b3;
/* XXX: I did that only to give same values as previous code */
a0 = W4 * (col[8*0] + ((1<<(COL_SHIFT-1))/W4));
a1 = a0;
a2 = a0;
a3 = a0;
a0 += + W2*col[8*2];
a1 += + W6*col[8*2];
a2 += - W6*col[8*2];
a3 += - W2*col[8*2];
MUL16(b0, W1, col[8*1]);
MUL16(b1, W3, col[8*1]);
MUL16(b2, W5, col[8*1]);
MUL16(b3, W7, col[8*1]);
MAC16(b0, + W3, col[8*3]);
MAC16(b1, - W7, col[8*3]);
MAC16(b2, - W1, col[8*3]);
MAC16(b3, - W5, col[8*3]);
if(col[8*4]){
a0 += + W4*col[8*4];
a1 += - W4*col[8*4];
a2 += - W4*col[8*4];
a3 += + W4*col[8*4];
}
if (col[8*5]) {
MAC16(b0, + W5, col[8*5]);
MAC16(b1, - W1, col[8*5]);
MAC16(b2, + W7, col[8*5]);
MAC16(b3, + W3, col[8*5]);
}
if(col[8*6]){
a0 += + W6*col[8*6];
a1 += - W2*col[8*6];
a2 += + W2*col[8*6];
a3 += - W6*col[8*6];
}
if (col[8*7]) {
MAC16(b0, + W7, col[8*7]);
MAC16(b1, - W5, col[8*7]);
MAC16(b2, + W3, col[8*7]);
MAC16(b3, - W1, col[8*7]);
}
col[0 ] = ((a0 + b0) >> COL_SHIFT);
col[8 ] = ((a1 + b1) >> COL_SHIFT);
col[16] = ((a2 + b2) >> COL_SHIFT);
col[24] = ((a3 + b3) >> COL_SHIFT);
col[32] = ((a3 - b3) >> COL_SHIFT);
col[40] = ((a2 - b2) >> COL_SHIFT);
col[48] = ((a1 - b1) >> COL_SHIFT);
col[56] = ((a0 - b0) >> COL_SHIFT);
}
void simple_idct_c(int16_t * const block)
{
int i;
for(i=0; i<8; i++)
idctRowCondDC(block + i*8);
for(i=0; i<8; i++)
idctSparseCol(block + i);
}
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