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![Måns Rullgård](/assets/img/avatar_default.png)
On PPC a leaf function has a 288-byte red zone below the stack pointer, sparing these functions the chore of setting up a full stack frame. When a function call is disguised within an inline asm block, the compiler might not adjust the stack pointer as required before a function call, resulting in the red zone being clobbered. Moving the entire function to pure asm avoids this problem and also results in somewhat better code. Originally committed as revision 24044 to svn://svn.ffmpeg.org/ffmpeg/trunk
148 lines
4.8 KiB
C
148 lines
4.8 KiB
C
/*
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* FFT/IFFT transforms
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* AltiVec-enabled
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* Copyright (c) 2009 Loren Merritt
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavcodec/fft.h"
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#include "util_altivec.h"
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#include "types_altivec.h"
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/**
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* Do a complex FFT with the parameters defined in ff_fft_init(). The
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* input data must be permuted before with s->revtab table. No
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* 1.0/sqrt(n) normalization is done.
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* AltiVec-enabled
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* This code assumes that the 'z' pointer is 16 bytes-aligned
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* It also assumes all FFTComplex are 8 bytes-aligned pair of float
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*/
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void ff_fft_calc_altivec(FFTContext *s, FFTComplex *z);
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void ff_fft_calc_interleave_altivec(FFTContext *s, FFTComplex *z);
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#if HAVE_GNU_AS
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static void ff_imdct_half_altivec(FFTContext *s, FFTSample *output, const FFTSample *input)
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{
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int j, k;
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int n = 1 << s->mdct_bits;
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int n4 = n >> 2;
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int n8 = n >> 3;
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int n32 = n >> 5;
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const uint16_t *revtabj = s->revtab;
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const uint16_t *revtabk = s->revtab+n4;
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const vec_f *tcos = (const vec_f*)(s->tcos+n8);
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const vec_f *tsin = (const vec_f*)(s->tsin+n8);
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const vec_f *pin = (const vec_f*)(input+n4);
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vec_f *pout = (vec_f*)(output+n4);
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/* pre rotation */
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k = n32-1;
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do {
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vec_f cos,sin,cos0,sin0,cos1,sin1,re,im,r0,i0,r1,i1,a,b,c,d;
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#define CMULA(p,o0,o1,o2,o3)\
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a = pin[ k*2+p]; /* { z[k].re, z[k].im, z[k+1].re, z[k+1].im } */\
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b = pin[-k*2-p-1]; /* { z[-k-2].re, z[-k-2].im, z[-k-1].re, z[-k-1].im } */\
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re = vec_perm(a, b, vcprm(0,2,s0,s2)); /* { z[k].re, z[k+1].re, z[-k-2].re, z[-k-1].re } */\
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im = vec_perm(a, b, vcprm(s3,s1,3,1)); /* { z[-k-1].im, z[-k-2].im, z[k+1].im, z[k].im } */\
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cos = vec_perm(cos0, cos1, vcprm(o0,o1,s##o2,s##o3)); /* { cos[k], cos[k+1], cos[-k-2], cos[-k-1] } */\
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sin = vec_perm(sin0, sin1, vcprm(o0,o1,s##o2,s##o3));\
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r##p = im*cos - re*sin;\
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i##p = re*cos + im*sin;
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#define STORE2(v,dst)\
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j = dst;\
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vec_ste(v, 0, output+j*2);\
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vec_ste(v, 4, output+j*2);
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#define STORE8(p)\
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a = vec_perm(r##p, i##p, vcprm(0,s0,0,s0));\
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b = vec_perm(r##p, i##p, vcprm(1,s1,1,s1));\
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c = vec_perm(r##p, i##p, vcprm(2,s2,2,s2));\
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d = vec_perm(r##p, i##p, vcprm(3,s3,3,s3));\
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STORE2(a, revtabk[ p*2-4]);\
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STORE2(b, revtabk[ p*2-3]);\
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STORE2(c, revtabj[-p*2+2]);\
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STORE2(d, revtabj[-p*2+3]);
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cos0 = tcos[k];
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sin0 = tsin[k];
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cos1 = tcos[-k-1];
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sin1 = tsin[-k-1];
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CMULA(0, 0,1,2,3);
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CMULA(1, 2,3,0,1);
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STORE8(0);
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STORE8(1);
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revtabj += 4;
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revtabk -= 4;
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k--;
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} while(k >= 0);
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ff_fft_calc_altivec(s, (FFTComplex*)output);
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/* post rotation + reordering */
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j = -n32;
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k = n32-1;
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do {
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vec_f cos,sin,re,im,a,b,c,d;
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#define CMULB(d0,d1,o)\
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re = pout[o*2];\
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im = pout[o*2+1];\
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cos = tcos[o];\
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sin = tsin[o];\
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d0 = im*sin - re*cos;\
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d1 = re*sin + im*cos;
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CMULB(a,b,j);
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CMULB(c,d,k);
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pout[2*j] = vec_perm(a, d, vcprm(0,s3,1,s2));
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pout[2*j+1] = vec_perm(a, d, vcprm(2,s1,3,s0));
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pout[2*k] = vec_perm(c, b, vcprm(0,s3,1,s2));
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pout[2*k+1] = vec_perm(c, b, vcprm(2,s1,3,s0));
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j++;
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k--;
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} while(k >= 0);
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}
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static void ff_imdct_calc_altivec(FFTContext *s, FFTSample *output, const FFTSample *input)
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{
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int k;
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int n = 1 << s->mdct_bits;
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int n4 = n >> 2;
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int n16 = n >> 4;
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vec_u32 sign = {1<<31,1<<31,1<<31,1<<31};
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vec_u32 *p0 = (vec_u32*)(output+n4);
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vec_u32 *p1 = (vec_u32*)(output+n4*3);
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ff_imdct_half_altivec(s, output+n4, input);
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for (k = 0; k < n16; k++) {
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vec_u32 a = p0[k] ^ sign;
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vec_u32 b = p1[-k-1];
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p0[-k-1] = vec_perm(a, a, vcprm(3,2,1,0));
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p1[k] = vec_perm(b, b, vcprm(3,2,1,0));
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}
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}
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#endif /* HAVE_GNU_AS */
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av_cold void ff_fft_init_altivec(FFTContext *s)
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{
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#if HAVE_GNU_AS
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s->fft_calc = ff_fft_calc_interleave_altivec;
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s->imdct_calc = ff_imdct_calc_altivec;
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s->imdct_half = ff_imdct_half_altivec;
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#endif
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}
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