gecko/media/libtheora/lib/dec/idct.c

269 lines
8.4 KiB
C

/********************************************************************
* *
* THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
* *
* THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2007 *
* by the Xiph.Org Foundation and contributors http://www.xiph.org/ *
* *
********************************************************************
function:
last mod: $Id: idct.c 15400 2008-10-15 12:10:58Z tterribe $
********************************************************************/
#include <string.h>
#include <ogg/ogg.h>
#include "dct.h"
#include "idct.h"
/*Performs an inverse 8 point Type-II DCT transform.
The output is scaled by a factor of 2 relative to the orthonormal version of
the transform.
_y: The buffer to store the result in.
Data will be placed in every 8th entry (e.g., in a column of an 8x8
block).
_x: The input coefficients.
The first 8 entries are used (e.g., from a row of an 8x8 block).*/
static void idct8(ogg_int16_t *_y,const ogg_int16_t _x[8]){
ogg_int32_t t[8];
ogg_int32_t r;
/*Stage 1:*/
/*0-1 butterfly.*/
t[0]=OC_C4S4*(ogg_int16_t)(_x[0]+_x[4])>>16;
t[1]=OC_C4S4*(ogg_int16_t)(_x[0]-_x[4])>>16;
/*2-3 rotation by 6pi/16.*/
t[2]=(OC_C6S2*_x[2]>>16)-(OC_C2S6*_x[6]>>16);
t[3]=(OC_C2S6*_x[2]>>16)+(OC_C6S2*_x[6]>>16);
/*4-7 rotation by 7pi/16.*/
t[4]=(OC_C7S1*_x[1]>>16)-(OC_C1S7*_x[7]>>16);
/*5-6 rotation by 3pi/16.*/
t[5]=(OC_C3S5*_x[5]>>16)-(OC_C5S3*_x[3]>>16);
t[6]=(OC_C5S3*_x[5]>>16)+(OC_C3S5*_x[3]>>16);
t[7]=(OC_C1S7*_x[1]>>16)+(OC_C7S1*_x[7]>>16);
/*Stage 2:*/
/*4-5 butterfly.*/
r=t[4]+t[5];
t[5]=OC_C4S4*(ogg_int16_t)(t[4]-t[5])>>16;
t[4]=r;
/*7-6 butterfly.*/
r=t[7]+t[6];
t[6]=OC_C4S4*(ogg_int16_t)(t[7]-t[6])>>16;
t[7]=r;
/*Stage 3:*/
/*0-3 butterfly.*/
r=t[0]+t[3];
t[3]=t[0]-t[3];
t[0]=r;
/*1-2 butterfly.*/
r=t[1]+t[2];
t[2]=t[1]-t[2];
t[1]=r;
/*6-5 butterfly.*/
r=t[6]+t[5];
t[5]=t[6]-t[5];
t[6]=r;
/*Stage 4:*/
/*0-7 butterfly.*/
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
/*1-6 butterfly.*/
_y[1<<3]=(ogg_int16_t)(t[1]+t[6]);
/*2-5 butterfly.*/
_y[2<<3]=(ogg_int16_t)(t[2]+t[5]);
/*3-4 butterfly.*/
_y[3<<3]=(ogg_int16_t)(t[3]+t[4]);
_y[4<<3]=(ogg_int16_t)(t[3]-t[4]);
_y[5<<3]=(ogg_int16_t)(t[2]-t[5]);
_y[6<<3]=(ogg_int16_t)(t[1]-t[6]);
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
}
/*Performs an inverse 8 point Type-II DCT transform.
The output is scaled by a factor of 2 relative to the orthonormal version of
the transform.
_y: The buffer to store the result in.
Data will be placed in every 8th entry (e.g., in a column of an 8x8
block).
_x: The input coefficients.
Only the first 4 entries are used.
The other 4 are assumed to be 0.*/
static void idct8_4(ogg_int16_t *_y,const ogg_int16_t _x[8]){
ogg_int32_t t[8];
ogg_int32_t r;
/*Stage 1:*/
t[0]=OC_C4S4*_x[0]>>16;
t[2]=OC_C6S2*_x[2]>>16;
t[3]=OC_C2S6*_x[2]>>16;
t[4]=OC_C7S1*_x[1]>>16;
t[5]=-(OC_C5S3*_x[3]>>16);
t[6]=OC_C3S5*_x[3]>>16;
t[7]=OC_C1S7*_x[1]>>16;
/*Stage 2:*/
r=t[4]+t[5];
t[5]=OC_C4S4*(ogg_int16_t)(t[4]-t[5])>>16;
t[4]=r;
r=t[7]+t[6];
t[6]=OC_C4S4*(ogg_int16_t)(t[7]-t[6])>>16;
t[7]=r;
/*Stage 3:*/
t[1]=t[0]+t[2];
t[2]=t[0]-t[2];
r=t[0]+t[3];
t[3]=t[0]-t[3];
t[0]=r;
r=t[6]+t[5];
t[5]=t[6]-t[5];
t[6]=r;
/*Stage 4:*/
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
_y[1<<3]=(ogg_int16_t)(t[1]+t[6]);
_y[2<<3]=(ogg_int16_t)(t[2]+t[5]);
_y[3<<3]=(ogg_int16_t)(t[3]+t[4]);
_y[4<<3]=(ogg_int16_t)(t[3]-t[4]);
_y[5<<3]=(ogg_int16_t)(t[2]-t[5]);
_y[6<<3]=(ogg_int16_t)(t[1]-t[6]);
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
}
/*Performs an inverse 8 point Type-II DCT transform.
The output is scaled by a factor of 2 relative to the orthonormal version of
the transform.
_y: The buffer to store the result in.
Data will be placed in every 8th entry (e.g., in a column of an 8x8
block).
_x: The input coefficients.
Only the first 3 entries are used.
The other 5 are assumed to be 0.*/
static void idct8_3(ogg_int16_t *_y,const ogg_int16_t _x[8]){
ogg_int32_t t[8];
ogg_int32_t r;
/*Stage 1:*/
t[0]=OC_C4S4*_x[0]>>16;
t[2]=OC_C6S2*_x[2]>>16;
t[3]=OC_C2S6*_x[2]>>16;
t[4]=OC_C7S1*_x[1]>>16;
t[7]=OC_C1S7*_x[1]>>16;
/*Stage 2:*/
t[5]=OC_C4S4*t[4]>>16;
t[6]=OC_C4S4*t[7]>>16;
/*Stage 3:*/
t[1]=t[0]+t[2];
t[2]=t[0]-t[2];
r=t[0]+t[3];
t[3]=t[0]-t[3];
t[0]=r;
r=t[6]+t[5];
t[5]=t[6]-t[5];
t[6]=r;
/*Stage 4:*/
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
_y[1<<3]=(ogg_int16_t)(t[1]+t[6]);
_y[2<<3]=(ogg_int16_t)(t[2]+t[5]);
_y[3<<3]=(ogg_int16_t)(t[3]+t[4]);
_y[4<<3]=(ogg_int16_t)(t[3]-t[4]);
_y[5<<3]=(ogg_int16_t)(t[2]-t[5]);
_y[6<<3]=(ogg_int16_t)(t[1]-t[6]);
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
}
/*Performs an inverse 8 point Type-II DCT transform.
The output is scaled by a factor of 2 relative to the orthonormal version of
the transform.
_y: The buffer to store the result in.
Data will be placed in every 8th entry (e.g., in a column of an 8x8
block).
_x: The input coefficients.
Only the first 2 entries are used.
The other 6 are assumed to be 0.*/
static void idct8_2(ogg_int16_t *_y,const ogg_int16_t _x[8]){
ogg_int32_t t[8];
ogg_int32_t r;
/*Stage 1:*/
t[0]=OC_C4S4*_x[0]>>16;
t[4]=OC_C7S1*_x[1]>>16;
t[7]=OC_C1S7*_x[1]>>16;
/*Stage 2:*/
t[5]=OC_C4S4*t[4]>>16;
t[6]=OC_C4S4*t[7]>>16;
/*Stage 3:*/
r=t[6]+t[5];
t[5]=t[6]-t[5];
t[6]=r;
/*Stage 4:*/
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
_y[1<<3]=(ogg_int16_t)(t[0]+t[6]);
_y[2<<3]=(ogg_int16_t)(t[0]+t[5]);
_y[3<<3]=(ogg_int16_t)(t[0]+t[4]);
_y[4<<3]=(ogg_int16_t)(t[0]-t[4]);
_y[5<<3]=(ogg_int16_t)(t[0]-t[5]);
_y[6<<3]=(ogg_int16_t)(t[0]-t[6]);
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
}
/*Performs an inverse 8 point Type-II DCT transform.
The output is scaled by a factor of 2 relative to the orthonormal version of
the transform.
_y: The buffer to store the result in.
Data will be placed in every 8th entry (e.g., in a column of an 8x8
block).
_x: The input coefficients.
Only the first entry is used.
The other 7 are assumed to be 0.*/
static void idct8_1(ogg_int16_t *_y,const ogg_int16_t _x[1]){
_y[0<<3]=_y[1<<3]=_y[2<<3]=_y[3<<3]=
_y[4<<3]=_y[5<<3]=_y[6<<3]=_y[7<<3]=(ogg_int16_t)(OC_C4S4*_x[0]>>16);
}
/*Performs an inverse 8x8 Type-II DCT transform.
The input is assumed to be scaled by a factor of 4 relative to orthonormal
version of the transform.
_y: The buffer to store the result in.
This may be the same as _x.
_x: The input coefficients. */
void oc_idct8x8_c(ogg_int16_t _y[64],const ogg_int16_t _x[64]){
const ogg_int16_t *in;
ogg_int16_t *end;
ogg_int16_t *out;
ogg_int16_t w[64];
/*Transform rows of x into columns of w.*/
for(in=_x,out=w,end=out+8;out<end;in+=8,out++)idct8(out,in);
/*Transform rows of w into columns of y.*/
for(in=w,out=_y,end=out+8;out<end;in+=8,out++)idct8(out,in);
/*Adjust for scale factor.*/
for(out=_y,end=out+64;out<end;out++)*out=(ogg_int16_t)(*out+8>>4);
}
/*Performs an inverse 8x8 Type-II DCT transform.
The input is assumed to be scaled by a factor of 4 relative to orthonormal
version of the transform.
All coefficients but the first 10 in zig-zag scan order are assumed to be 0:
x x x x 0 0 0 0
x x x 0 0 0 0 0
x x 0 0 0 0 0 0
x 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
_y: The buffer to store the result in.
This may be the same as _x.
_x: The input coefficients. */
void oc_idct8x8_10_c(ogg_int16_t _y[64],const ogg_int16_t _x[64]){
const ogg_int16_t *in;
ogg_int16_t *end;
ogg_int16_t *out;
ogg_int16_t w[64];
/*Transform rows of x into columns of w.*/
idct8_4(w,_x);
idct8_3(w+1,_x+8);
idct8_2(w+2,_x+16);
idct8_1(w+3,_x+24);
/*Transform rows of w into columns of y.*/
for(in=w,out=_y,end=out+8;out<end;in+=8,out++)idct8_4(out,in);
/*Adjust for scale factor.*/
for(out=_y,end=out+64;out<end;out++)*out=(ogg_int16_t)(*out+8>>4);
}