📄 cook_mdct.c
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/*
* The following (normalized modified discrete cosine transform)
* is taken from the OggVorbis 'TREMOR' source code.
*
* It has been modified for the ffmpeg cook fixed point decoder.
*/
/********************************************************************
* *
* THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002 *
* BY THE Xiph.Org FOUNDATION http://www.xiph.org/ *
* *
********************************************************************
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
- Neither the name of the Xiph.org Foundation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*********************************************************************
function: normalized modified discrete cosine transform
power of two length transform only [64 <= n ]
last mod: $Id: cook_mdct.c,v 1.2 2008/03/03 08:11:34 dsqiu Exp $
Original algorithm adapted long ago from _The use of multirate filter
banks for coding of high quality digital audio_, by T. Sporer,
K. Brandenburg and B. Edler, collection of the European Signal
Processing Conference (EUSIPCO), Amsterdam, June 1992, Vol.1, pp
211-214
The below code implements an algorithm that no longer looks much like
that presented in the paper, but the basic structure remains if you
dig deep enough to see it.
This module DOES NOT INCLUDE code to generate/apply the window
function. Everybody has their own weird favorite including me... I
happen to like the properties of y=sin(.5PI*sin^2(x)), but others may
vehemently disagree.
********************************************************************/
#define STIN static inline
typedef int32_t ogg_int32_t;
#define DATA_TYPE ogg_int32_t
#define REG_TYPE register ogg_int32_t
#define LOOKUP_T const uint16_t
static inline ogg_int32_t MULT32(ogg_int32_t x, ogg_int32_t y) {
return fixp_mult_pow2(x, y, -1);
}
static inline ogg_int32_t MULT31(ogg_int32_t x, ogg_int32_t y) {
return fixp_mult(x, y);
}
/*
* This should be used as a memory barrier, forcing all cached values in
* registers to wr writen back to memory. Might or might not be beneficial
* depending on the architecture and compiler.
*/
#define MB()
/*
* The XPROD functions are meant to optimize the cross products found all
* over the place in mdct.c by forcing memory operation ordering to avoid
* unnecessary register reloads as soon as memory is being written to.
* However this is only beneficial on CPUs with a sane number of general
* purpose registers which exclude the Intel x86. On Intel, better let the
* compiler actually reload registers directly from original memory by using
* macros.
*/
#ifdef __i386__
#define XPROD32(_a, _b, _t, _v, _x, _y) \
{ *(_x)=MULT32(_a,_t)+MULT32(_b,_v); \
*(_y)=MULT32(_b,_t)-MULT32(_a,_v); }
#define XPROD31(_a, _b, _t, _v, _x, _y) \
{ *(_x)=MULT31(_a,_t)+MULT31(_b,_v); \
*(_y)=MULT31(_b,_t)-MULT31(_a,_v); }
#define XNPROD31(_a, _b, _t, _v, _x, _y) \
{ *(_x)=MULT31(_a,_t)-MULT31(_b,_v); \
*(_y)=MULT31(_b,_t)+MULT31(_a,_v); }
#else
static inline void XPROD32(ogg_int32_t a, ogg_int32_t b,
ogg_int32_t t, ogg_int32_t v,
ogg_int32_t *x, ogg_int32_t *y)
{
*x = MULT32(a, t) + MULT32(b, v);
*y = MULT32(b, t) - MULT32(a, v);
}
static inline void XPROD31(ogg_int32_t a, ogg_int32_t b,
ogg_int32_t t, ogg_int32_t v,
ogg_int32_t *x, ogg_int32_t *y)
{
*x = MULT31(a, t) + MULT31(b, v);
*y = MULT31(b, t) - MULT31(a, v);
}
static inline void XNPROD31(ogg_int32_t a, ogg_int32_t b,
ogg_int32_t t, ogg_int32_t v,
ogg_int32_t *x, ogg_int32_t *y)
{
*x = MULT31(a, t) - MULT31(b, v);
*y = MULT31(b, t) + MULT31(a, v);
}
#endif
/* 8 point butterfly (in place) */
STIN void mdct_butterfly_8(DATA_TYPE *x){
REG_TYPE r0 = x[4] + x[0];
REG_TYPE r1 = x[4] - x[0];
REG_TYPE r2 = x[5] + x[1];
REG_TYPE r3 = x[5] - x[1];
REG_TYPE r4 = x[6] + x[2];
REG_TYPE r5 = x[6] - x[2];
REG_TYPE r6 = x[7] + x[3];
REG_TYPE r7 = x[7] - x[3];
x[0] = r5 + r3;
x[1] = r7 - r1;
x[2] = r5 - r3;
x[3] = r7 + r1;
x[4] = r4 - r0;
x[5] = r6 - r2;
x[6] = r4 + r0;
x[7] = r6 + r2;
MB();
}
/* 16 point butterfly (in place, 4 register) */
STIN void mdct_butterfly_16(DATA_TYPE *x){
REG_TYPE r0, r1;
r0 = x[ 0] - x[ 8]; x[ 8] += x[ 0];
r1 = x[ 1] - x[ 9]; x[ 9] += x[ 1];
x[ 0] = MULT31((r0 + r1) , cPI2_8);
x[ 1] = MULT31((r1 - r0) , cPI2_8);
MB();
r0 = x[10] - x[ 2]; x[10] += x[ 2];
r1 = x[ 3] - x[11]; x[11] += x[ 3];
x[ 2] = r1; x[ 3] = r0;
MB();
r0 = x[12] - x[ 4]; x[12] += x[ 4];
r1 = x[13] - x[ 5]; x[13] += x[ 5];
x[ 4] = MULT31((r0 - r1) , cPI2_8);
x[ 5] = MULT31((r0 + r1) , cPI2_8);
MB();
r0 = x[14] - x[ 6]; x[14] += x[ 6];
r1 = x[15] - x[ 7]; x[15] += x[ 7];
x[ 6] = r0; x[ 7] = r1;
MB();
mdct_butterfly_8(x);
mdct_butterfly_8(x+8);
}
/* 32 point butterfly (in place, 4 register) */
STIN void mdct_butterfly_32(DATA_TYPE *x){
REG_TYPE r0, r1;
r0 = x[30] - x[14]; x[30] += x[14];
r1 = x[31] - x[15]; x[31] += x[15];
x[14] = r0; x[15] = r1;
MB();
r0 = x[28] - x[12]; x[28] += x[12];
r1 = x[29] - x[13]; x[29] += x[13];
XNPROD31( r0, r1, cPI1_8, cPI3_8, &x[12], &x[13] );
MB();
r0 = x[26] - x[10]; x[26] += x[10];
r1 = x[27] - x[11]; x[27] += x[11];
x[10] = MULT31((r0 - r1) , cPI2_8);
x[11] = MULT31((r0 + r1) , cPI2_8);
MB();
r0 = x[24] - x[ 8]; x[24] += x[ 8];
r1 = x[25] - x[ 9]; x[25] += x[ 9];
XNPROD31( r0, r1, cPI3_8, cPI1_8, &x[ 8], &x[ 9] );
MB();
r0 = x[22] - x[ 6]; x[22] += x[ 6];
r1 = x[ 7] - x[23]; x[23] += x[ 7];
x[ 6] = r1; x[ 7] = r0;
MB();
r0 = x[ 4] - x[20]; x[20] += x[ 4];
r1 = x[ 5] - x[21]; x[21] += x[ 5];
XPROD31 ( r0, r1, cPI3_8, cPI1_8, &x[ 4], &x[ 5] );
MB();
r0 = x[ 2] - x[18]; x[18] += x[ 2];
r1 = x[ 3] - x[19]; x[19] += x[ 3];
x[ 2] = MULT31((r1 + r0) , cPI2_8);
x[ 3] = MULT31((r1 - r0) , cPI2_8);
MB();
r0 = x[ 0] - x[16]; x[16] += x[ 0];
r1 = x[ 1] - x[17]; x[17] += x[ 1];
XPROD31 ( r0, r1, cPI1_8, cPI3_8, &x[ 0], &x[ 1] );
MB();
mdct_butterfly_16(x);
mdct_butterfly_16(x+16);
}
/* N/stage point generic N stage butterfly (in place, 2 register) */
STIN void mdct_butterfly_generic
(DATA_TYPE *x, int points, int step, LOOKUP_T *sincos_lookup){
LOOKUP_T *T = sincos_lookup;
DATA_TYPE *x1 = x + points - 8;
DATA_TYPE *x2 = x + (points>>1) - 8;
REG_TYPE r0;
REG_TYPE r1;
//av_log(0, 0, "bfly: points=%d, step=%d\n", points, step);
do{
r0 = x1[6] - x2[6]; x1[6] += x2[6];
r1 = x2[7] - x1[7]; x1[7] += x2[7];
XPROD31( r1, r0, T[0], T[1], &x2[6], &x2[7] ); T+=step;
r0 = x1[4] - x2[4]; x1[4] += x2[4];
r1 = x2[5] - x1[5]; x1[5] += x2[5];
XPROD31( r1, r0, T[0], T[1], &x2[4], &x2[5] ); T+=step;
r0 = x1[2] - x2[2]; x1[2] += x2[2];
r1 = x2[3] - x1[3]; x1[3] += x2[3];
XPROD31( r1, r0, T[0], T[1], &x2[2], &x2[3] ); T+=step;
r0 = x1[0] - x2[0]; x1[0] += x2[0];
r1 = x2[1] - x1[1]; x1[1] += x2[1];
XPROD31( r1, r0, T[0], T[1], &x2[0], &x2[1] ); T+=step;
x1-=8; x2-=8;
}while(T<sincos_lookup+2048);
do{
r0 = x1[6] - x2[6]; x1[6] += x2[6];
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