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Merge from branches/mdctexp - faster ifft+imdct in codec lib

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24712 a1c6a512-1295-4272-9138-f99709370657
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Dave Hooper 2010-02-17 00:49:53 +00:00
parent 62257ebc38
commit 42774d3128
31 changed files with 2000 additions and 320 deletions
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apps/codecs/lib/mdct.c Normal file
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/*
* Fixed Point IMDCT
* Copyright (c) 2002 The FFmpeg Project.
* Copyright (c) 2010 Dave Hooper, Mohamed Tarek, Michael Giacomelli
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "codeclib.h"
#include "mdct.h"
#include "asm_arm.h"
#include "asm_mcf5249.h"
#include "codeclib_misc.h"
#include "mdct_lookup.h"
/**
* Compute the middle half of the inverse MDCT of size N = 2^nbits
* thus excluding the parts that can be derived by symmetry
* @param output N/2 samples
* @param input N/2 samples
*
* NOTE - CANNOT CURRENTLY OPERATE IN PLACE (input and output must
* not overlap or intersect at all)
*/
void ff_imdct_half(unsigned int nbits, fixed32 *output, const fixed32 *input)
{
int n8, n4, n2, n, j;
const fixed32 *in1, *in2;
n = 1 << nbits;
n2 = n >> 1;
n4 = n >> 2;
n8 = n >> 3;
FFTComplex *z = (FFTComplex *)output;
/* pre rotation */
in1 = input;
in2 = input + n2 - 1;
/* revtab comes from the fft; revtab table is sized for N=4096 size fft = 2^12.
The fft is size N/4 so s->nbits-2, so our shift needs to be (12-(nbits-2)) */
const int revtab_shift = (14- nbits);
/* bitreverse reorder the input and rotate; result here is in OUTPUT ... */
/* (note that when using the current split radix, the bitreverse ordering is
complex, meaning that this reordering cannot easily be done in-place) */
/* Using the following pdf, you can see that it is possible to rearrange
the 'classic' pre/post rotate with an alternative one that enables
us to use fewer distinct twiddle factors.
http://www.eurasip.org/Proceedings/Eusipco/Eusipco2006/papers/1568980508.pdf
For prerotation, the factors are just sin,cos(2PI*i/N)
For postrotation, the factors are sin,cos(2PI*(i+1/4)/N)
Therefore, prerotation can immediately reuse the same twiddles as fft
(for postrotation it's still a bit complex, so this is still using
an mdct-local set of twiddles to do that part)
*/
const int32_t *T = sincos_lookup0;
const int step = 2<<(12-nbits);
const uint16_t * p_revtab=revtab;
{
const uint16_t * const p_revtab_end = p_revtab + n8;
while(LIKELY(p_revtab < p_revtab_end))
{
j = (*p_revtab)>>revtab_shift;
XNPROD31(*in2, *in1, T[1], T[0], &z[j].re, &z[j].im );
T += step;
in1 += 2;
in2 -= 2;
p_revtab++;
j = (*p_revtab)>>revtab_shift;
XNPROD31(*in2, *in1, T[1], T[0], &z[j].re, &z[j].im );
T += step;
in1 += 2;
in2 -= 2;
p_revtab++;
}
}
{
const uint16_t * const p_revtab_end = p_revtab + n8;
while(LIKELY(p_revtab < p_revtab_end))
{
j = (*p_revtab)>>revtab_shift;
XNPROD31(*in2, *in1, T[0], T[1], &z[j].re, &z[j].im);
T -= step;
in1 += 2;
in2 -= 2;
p_revtab++;
j = (*p_revtab)>>revtab_shift;
XNPROD31(*in2, *in1, T[0], T[1], &z[j].re, &z[j].im);
T -= step;
in1 += 2;
in2 -= 2;
p_revtab++;
}
}
/* ... and so fft runs in OUTPUT buffer */
ff_fft_calc_c(nbits-2, z);
/* post rotation + reordering. now keeps the result within the OUTPUT buffer */
switch( nbits )
{
default:
{
fixed32 * z1 = (fixed32 *)(&z[0]);
fixed32 * z2 = (fixed32 *)(&z[n4-1]);
int magic_step = step>>2;
int newstep;
if(n<=1024)
{
T = sincos_lookup0 + magic_step;
newstep = step>>1;
}
else
{
T = sincos_lookup1;
newstep = 2;
}
while(z1<z2)
{
fixed32 r0,i0,r1,i1;
XNPROD31_R(z1[1], z1[0], T[0], T[1], r0, i1 ); T+=newstep;
XNPROD31_R(z2[1], z2[0], T[1], T[0], r1, i0 ); T+=newstep;
z1[0] = r0;
z1[1] = i0;
z2[0] = r1;
z2[1] = i1;
z1+=2;
z2-=2;
}
break;
}
case 12: /* n=4096 */
{
/* linear interpolation (50:50) between sincos_lookup0 and sincos_lookup1 */
const int32_t * V = sincos_lookup1;
T = sincos_lookup0;
int32_t t0,t1,v0,v1;
fixed32 * z1 = (fixed32 *)(&z[0]);
fixed32 * z2 = (fixed32 *)(&z[n4-1]);
t0 = T[0]>>1; t1=T[1]>>1;
while(z1<z2)
{
fixed32 r0,i0,r1,i1;
t0 += (v0 = (V[0]>>1));
t1 += (v1 = (V[1]>>1));
XNPROD31_R(z1[1], z1[0], t0, t1, r0, i1 );
T+=2;
v0 += (t0 = (T[0]>>1));
v1 += (t1 = (T[1]>>1));
XNPROD31_R(z2[1], z2[0], v1, v0, r1, i0 );
z1[0] = r0;
z1[1] = i0;
z2[0] = r1;
z2[1] = i1;
z1+=2;
z2-=2;
V+=2;
}
break;
}
case 13: /* n = 8192 */
{
/* weight linear interpolation between sincos_lookup0 and sincos_lookup1
specifically: 25:75 for first twiddle and 75:25 for second twiddle */
const int32_t * V = sincos_lookup1;
T = sincos_lookup0;
int32_t t0,t1,v0,v1,q0,q1;
fixed32 * z1 = (fixed32 *)(&z[0]);
fixed32 * z2 = (fixed32 *)(&z[n4-1]);
t0 = T[0]; t1=T[1];
while(z1<z2)
{
fixed32 r0,i0,r1,i1;
v0 = V[0]; v1 = V[1];
t0 += (q0 = (v0-t0)>>1);
t1 += (q1 = (v1-t1)>>1);
XNPROD31_R(z1[1], z1[0], t0, t1, r0, i1 );
t0 = v0-q0;
t1 = v1-q1;
XNPROD31_R(z2[1], z2[0], t1, t0, r1, i0 );
z1[0] = r0;
z1[1] = i0;
z2[0] = r1;
z2[1] = i1;
z1+=2;
z2-=2;
T+=2;
t0 = T[0]; t1 = T[1];
v0 += (q0 = (t0-v0)>>1);
v1 += (q1 = (t1-v1)>>1);
XNPROD31_R(z1[1], z1[0], v0, v1, r0, i1 );
v0 = t0-q0;
v1 = t1-q1;
XNPROD31_R(z2[1], z2[0], v1, v0, r1, i0 );
z1[0] = r0;
z1[1] = i0;
z2[0] = r1;
z2[1] = i1;
z1+=2;
z2-=2;
V+=2;
}
break;
}
}
}
/**
* Compute inverse MDCT of size N = 2^nbits
* @param output N samples
* @param input N/2 samples
* "In-place" processing can be achieved provided that:
* [0 .. N/2-1 | N/2 .. N-1 ]
* <----input---->
* <-----------output----------->
*
*/
void ff_imdct_calc(unsigned int nbits, fixed32 *output, const fixed32 *input)
{
const int n = (1<<nbits);
const int n2 = (n>>1);
const int n4 = (n>>2);
ff_imdct_half(nbits,output+n2,input);
/* reflect the half imdct into the full N samples */
/* TODO: this could easily be optimised more! */
fixed32 * in_r, * in_r2, * out_r, * out_r2;
out_r = output;
out_r2 = output+n2-8;
in_r = output+n2+n4-8;
while(out_r<out_r2)
{
out_r[0] = -(out_r2[7] = in_r[7]);
out_r[1] = -(out_r2[6] = in_r[6]);
out_r[2] = -(out_r2[5] = in_r[5]);
out_r[3] = -(out_r2[4] = in_r[4]);
out_r[4] = -(out_r2[3] = in_r[3]);
out_r[5] = -(out_r2[2] = in_r[2]);
out_r[6] = -(out_r2[1] = in_r[1]);
out_r[7] = -(out_r2[0] = in_r[0]);
in_r -= 8;
out_r += 8;
out_r2 -= 8;
}
in_r = output + n2+n4;
in_r2 = output + n-4;
out_r = output + n2;
out_r2 = output + n2 + n4 - 4;
while(in_r<in_r2)
{
register fixed32 t0,t1,t2,t3;
register fixed32 s0,s1,s2,s3;
//simultaneously do the following things:
// 1. copy range from [n2+n4 .. n-1] to range[n2 .. n2+n4-1]
// 2. reflect range from [n2+n4 .. n-1] inplace
//
// [ | ]
// ^a -> <- ^b ^c -> <- ^d
//
// #1: copy from ^c to ^a
// #2: copy from ^d to ^b
// #3: swap ^c and ^d in place
//
// #1 pt1 : load 4 words from ^c.
t0=in_r[0]; t1=in_r[1]; t2=in_r[2]; t3=in_r[3];
// #1 pt2 : write to ^a
out_r[0]=t0;out_r[1]=t1;out_r[2]=t2;out_r[3]=t3;
// #2 pt1 : load 4 words from ^d
s0=in_r2[0];s1=in_r2[1];s2=in_r2[2];s3=in_r2[3];
// #2 pt2 : write to ^b
out_r2[0]=s0;out_r2[1]=s1;out_r2[2]=s2;out_r2[3]=s3;
// #3 pt1 : write words from #2 to ^c
in_r[0]=s3;in_r[1]=s2;in_r[2]=s1;in_r[3]=s0;
// #3 pt2 : write words from #1 to ^d
in_r2[0]=t3;in_r2[1]=t2;in_r2[2]=t1;in_r2[3]=t0;
in_r += 4;
in_r2 -= 4;
out_r += 4;
out_r2 -= 4;
}
}
static const long cordic_circular_gain = 0xb2458939; /* 0.607252929 */
/* Table of values of atan(2^-i) in 0.32 format fractions of pi where pi = 0xffffffff / 2 */
static const unsigned long atan_table[] = {
0x1fffffff, /* +0.785398163 (or pi/4) */
0x12e4051d, /* +0.463647609 */
0x09fb385b, /* +0.244978663 */
0x051111d4, /* +0.124354995 */
0x028b0d43, /* +0.062418810 */
0x0145d7e1, /* +0.031239833 */
0x00a2f61e, /* +0.015623729 */
0x00517c55, /* +0.007812341 */
0x0028be53, /* +0.003906230 */
0x00145f2e, /* +0.001953123 */
0x000a2f98, /* +0.000976562 */
0x000517cc, /* +0.000488281 */
0x00028be6, /* +0.000244141 */
0x000145f3, /* +0.000122070 */
0x0000a2f9, /* +0.000061035 */
0x0000517c, /* +0.000030518 */
0x000028be, /* +0.000015259 */
0x0000145f, /* +0.000007629 */
0x00000a2f, /* +0.000003815 */
0x00000517, /* +0.000001907 */
0x0000028b, /* +0.000000954 */
0x00000145, /* +0.000000477 */
0x000000a2, /* +0.000000238 */
0x00000051, /* +0.000000119 */
0x00000028, /* +0.000000060 */
0x00000014, /* +0.000000030 */
0x0000000a, /* +0.000000015 */
0x00000005, /* +0.000000007 */
0x00000002, /* +0.000000004 */
0x00000001, /* +0.000000002 */
0x00000000, /* +0.000000001 */
0x00000000, /* +0.000000000 */
};
/**
* Implements sin and cos using CORDIC rotation.
*
* @param phase has range from 0 to 0xffffffff, representing 0 and
* 2*pi respectively.
* @param cos return address for cos
* @return sin of phase, value is a signed value from LONG_MIN to LONG_MAX,
* representing -1 and 1 respectively.
*
* Gives at least 24 bits precision (last 2-8 bits or so are probably off)
*/
long fsincos(unsigned long phase, fixed32 *cos)
{
int32_t x, x1, y, y1;
unsigned long z, z1;
int i;
/* Setup initial vector */
x = cordic_circular_gain;
y = 0;
z = phase;
/* The phase has to be somewhere between 0..pi for this to work right */
if (z < 0xffffffff / 4) {
/* z in first quadrant, z += pi/2 to correct */
x = -x;
z += 0xffffffff / 4;
} else if (z < 3 * (0xffffffff / 4)) {
/* z in third quadrant, z -= pi/2 to correct */
z -= 0xffffffff / 4;
} else {
/* z in fourth quadrant, z -= 3pi/2 to correct */
x = -x;
z -= 3 * (0xffffffff / 4);
}
/* Each iteration adds roughly 1-bit of extra precision */
for (i = 0; i < 31; i++) {
x1 = x >> i;
y1 = y >> i;
z1 = atan_table[i];
/* Decided which direction to rotate vector. Pivot point is pi/2 */
if (z >= 0xffffffff / 4) {
x -= y1;
y += x1;
z -= z1;
} else {
x += y1;
y -= x1;
z += z1;
}
}
if (cos)
*cos = x;
return y;
}