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ffmpeg/libavutil/tx.c

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/*
* Copyright (c) 2019 Lynne <dev@lynne.ee>
* Power of two FFT:
* Copyright (c) 2008 Loren Merritt
* Copyright (c) 2002 Fabrice Bellard
* Partly based on libdjbfft by D. J. Bernstein
*
* This file is part of FFmpeg.
*
* FFmpeg 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 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stddef.h>
#include "tx.h"
#include "thread.h"
#include "mem.h"
#include "avassert.h"
typedef float FFTSample;
typedef AVComplexFloat FFTComplex;
struct AVTXContext {
int n; /* Nptwo part */
int m; /* Ptwo part */
FFTComplex *exptab; /* MDCT exptab */
FFTComplex *tmp; /* Temporary buffer needed for all compound transforms */
int *pfatab; /* Input/Output mapping for compound transforms */
int *revtab; /* Input mapping for power of two transforms */
};
#define FFT_NAME(x) x
#define COSTABLE(size) \
static DECLARE_ALIGNED(32, FFTSample, FFT_NAME(ff_cos_##size))[size/2]
static FFTSample * const FFT_NAME(ff_cos_tabs)[18];
COSTABLE(16);
COSTABLE(32);
COSTABLE(64);
COSTABLE(128);
COSTABLE(256);
COSTABLE(512);
COSTABLE(1024);
COSTABLE(2048);
COSTABLE(4096);
COSTABLE(8192);
COSTABLE(16384);
COSTABLE(32768);
COSTABLE(65536);
COSTABLE(131072);
static av_cold void init_ff_cos_tabs(int index)
{
int m = 1 << index;
double freq = 2*M_PI/m;
FFTSample *tab = FFT_NAME(ff_cos_tabs)[index];
for(int i = 0; i <= m/4; i++)
tab[i] = cos(i*freq);
for(int i = 1; i < m/4; i++)
tab[m/2 - i] = tab[i];
}
typedef struct CosTabsInitOnce {
void (*func)(void);
AVOnce control;
} CosTabsInitOnce;
#define INIT_FF_COS_TABS_FUNC(index, size) \
static av_cold void init_ff_cos_tabs_ ## size (void) \
{ \
init_ff_cos_tabs(index); \
}
INIT_FF_COS_TABS_FUNC(4, 16)
INIT_FF_COS_TABS_FUNC(5, 32)
INIT_FF_COS_TABS_FUNC(6, 64)
INIT_FF_COS_TABS_FUNC(7, 128)
INIT_FF_COS_TABS_FUNC(8, 256)
INIT_FF_COS_TABS_FUNC(9, 512)
INIT_FF_COS_TABS_FUNC(10, 1024)
INIT_FF_COS_TABS_FUNC(11, 2048)
INIT_FF_COS_TABS_FUNC(12, 4096)
INIT_FF_COS_TABS_FUNC(13, 8192)
INIT_FF_COS_TABS_FUNC(14, 16384)
INIT_FF_COS_TABS_FUNC(15, 32768)
INIT_FF_COS_TABS_FUNC(16, 65536)
INIT_FF_COS_TABS_FUNC(17, 131072)
static CosTabsInitOnce cos_tabs_init_once[] = {
{ NULL },
{ NULL },
{ NULL },
{ NULL },
{ init_ff_cos_tabs_16, AV_ONCE_INIT },
{ init_ff_cos_tabs_32, AV_ONCE_INIT },
{ init_ff_cos_tabs_64, AV_ONCE_INIT },
{ init_ff_cos_tabs_128, AV_ONCE_INIT },
{ init_ff_cos_tabs_256, AV_ONCE_INIT },
{ init_ff_cos_tabs_512, AV_ONCE_INIT },
{ init_ff_cos_tabs_1024, AV_ONCE_INIT },
{ init_ff_cos_tabs_2048, AV_ONCE_INIT },
{ init_ff_cos_tabs_4096, AV_ONCE_INIT },
{ init_ff_cos_tabs_8192, AV_ONCE_INIT },
{ init_ff_cos_tabs_16384, AV_ONCE_INIT },
{ init_ff_cos_tabs_32768, AV_ONCE_INIT },
{ init_ff_cos_tabs_65536, AV_ONCE_INIT },
{ init_ff_cos_tabs_131072, AV_ONCE_INIT },
};
static FFTSample * const FFT_NAME(ff_cos_tabs)[] = {
NULL, NULL, NULL, NULL,
FFT_NAME(ff_cos_16),
FFT_NAME(ff_cos_32),
FFT_NAME(ff_cos_64),
FFT_NAME(ff_cos_128),
FFT_NAME(ff_cos_256),
FFT_NAME(ff_cos_512),
FFT_NAME(ff_cos_1024),
FFT_NAME(ff_cos_2048),
FFT_NAME(ff_cos_4096),
FFT_NAME(ff_cos_8192),
FFT_NAME(ff_cos_16384),
FFT_NAME(ff_cos_32768),
FFT_NAME(ff_cos_65536),
FFT_NAME(ff_cos_131072),
};
static av_cold void ff_init_ff_cos_tabs(int index)
{
ff_thread_once(&cos_tabs_init_once[index].control,
cos_tabs_init_once[index].func);
}
static AVOnce tabs_53_once = AV_ONCE_INIT;
static DECLARE_ALIGNED(32, FFTComplex, FFT_NAME(ff_53_tabs))[4];
static av_cold void ff_init_53_tabs(void)
{
ff_53_tabs[0] = (FFTComplex){ cos(2 * M_PI / 12), cos(2 * M_PI / 12) };
ff_53_tabs[1] = (FFTComplex){ 0.5, 0.5 };
ff_53_tabs[2] = (FFTComplex){ cos(2 * M_PI / 5), sin(2 * M_PI / 5) };
ff_53_tabs[3] = (FFTComplex){ cos(2 * M_PI / 10), sin(2 * M_PI / 10) };
}
#define BF(x, y, a, b) do { \
x = (a) - (b); \
y = (a) + (b); \
} while (0)
#define CMUL(dre, dim, are, aim, bre, bim) do { \
(dre) = (are) * (bre) - (aim) * (bim); \
(dim) = (are) * (bim) + (aim) * (bre); \
} while (0)
#define CMUL3(c, a, b) CMUL((c).re, (c).im, (a).re, (a).im, (b).re, (b).im)
static av_always_inline void fft3(FFTComplex *out, FFTComplex *in,
ptrdiff_t stride)
{
FFTComplex tmp[2];
tmp[0].re = in[1].im - in[2].im;
tmp[0].im = in[1].re - in[2].re;
tmp[1].re = in[1].re + in[2].re;
tmp[1].im = in[1].im + in[2].im;
out[0*stride].re = in[0].re + tmp[1].re;
out[0*stride].im = in[0].im + tmp[1].im;
tmp[0].re *= ff_53_tabs[0].re;
tmp[0].im *= ff_53_tabs[0].im;
tmp[1].re *= ff_53_tabs[1].re;
tmp[1].im *= ff_53_tabs[1].re;
out[1*stride].re = in[0].re - tmp[1].re + tmp[0].re;
out[1*stride].im = in[0].im - tmp[1].im - tmp[0].im;
out[2*stride].re = in[0].re - tmp[1].re - tmp[0].re;
out[2*stride].im = in[0].im - tmp[1].im + tmp[0].im;
}
#define DECL_FFT5(NAME, D0, D1, D2, D3, D4) \
static av_always_inline void NAME(FFTComplex *out, FFTComplex *in, \
ptrdiff_t stride) \
{ \
FFTComplex z0[4], t[6]; \
\
t[0].re = in[1].re + in[4].re; \
t[0].im = in[1].im + in[4].im; \
t[1].im = in[1].re - in[4].re; \
t[1].re = in[1].im - in[4].im; \
t[2].re = in[2].re + in[3].re; \
t[2].im = in[2].im + in[3].im; \
t[3].im = in[2].re - in[3].re; \
t[3].re = in[2].im - in[3].im; \
\
out[D0*stride].re = in[0].re + in[1].re + in[2].re + \
in[3].re + in[4].re; \
out[D0*stride].im = in[0].im + in[1].im + in[2].im + \
in[3].im + in[4].im; \
\
t[4].re = ff_53_tabs[2].re * t[2].re - ff_53_tabs[3].re * t[0].re; \
t[4].im = ff_53_tabs[2].re * t[2].im - ff_53_tabs[3].re * t[0].im; \
t[0].re = ff_53_tabs[2].re * t[0].re - ff_53_tabs[3].re * t[2].re; \
t[0].im = ff_53_tabs[2].re * t[0].im - ff_53_tabs[3].re * t[2].im; \
t[5].re = ff_53_tabs[2].im * t[3].re - ff_53_tabs[3].im * t[1].re; \
t[5].im = ff_53_tabs[2].im * t[3].im - ff_53_tabs[3].im * t[1].im; \
t[1].re = ff_53_tabs[2].im * t[1].re + ff_53_tabs[3].im * t[3].re; \
t[1].im = ff_53_tabs[2].im * t[1].im + ff_53_tabs[3].im * t[3].im; \
\
z0[0].re = t[0].re - t[1].re; \
z0[0].im = t[0].im - t[1].im; \
z0[1].re = t[4].re + t[5].re; \
z0[1].im = t[4].im + t[5].im; \
\
z0[2].re = t[4].re - t[5].re; \
z0[2].im = t[4].im - t[5].im; \
z0[3].re = t[0].re + t[1].re; \
z0[3].im = t[0].im + t[1].im; \
\
out[D1*stride].re = in[0].re + z0[3].re; \
out[D1*stride].im = in[0].im + z0[0].im; \
out[D2*stride].re = in[0].re + z0[2].re; \
out[D2*stride].im = in[0].im + z0[1].im; \
out[D3*stride].re = in[0].re + z0[1].re; \
out[D3*stride].im = in[0].im + z0[2].im; \
out[D4*stride].re = in[0].re + z0[0].re; \
out[D4*stride].im = in[0].im + z0[3].im; \
}
DECL_FFT5(fft5, 0, 1, 2, 3, 4)
DECL_FFT5(fft5_m1, 0, 6, 12, 3, 9)
DECL_FFT5(fft5_m2, 10, 1, 7, 13, 4)
DECL_FFT5(fft5_m3, 5, 11, 2, 8, 14)
static av_always_inline void fft15(FFTComplex *out, FFTComplex *in,
ptrdiff_t stride)
{
FFTComplex tmp[15];
for (int i = 0; i < 5; i++)
fft3(tmp + i, in + i*3, 5);
fft5_m1(out, tmp + 0, stride);
fft5_m2(out, tmp + 5, stride);
fft5_m3(out, tmp + 10, stride);
}
#define BUTTERFLIES(a0,a1,a2,a3) {\
BF(t3, t5, t5, t1);\
BF(a2.re, a0.re, a0.re, t5);\
BF(a3.im, a1.im, a1.im, t3);\
BF(t4, t6, t2, t6);\
BF(a3.re, a1.re, a1.re, t4);\
BF(a2.im, a0.im, a0.im, t6);\
}
// force loading all the inputs before storing any.
// this is slightly slower for small data, but avoids store->load aliasing
// for addresses separated by large powers of 2.
#define BUTTERFLIES_BIG(a0,a1,a2,a3) {\
FFTSample r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
BF(t3, t5, t5, t1);\
BF(a2.re, a0.re, r0, t5);\
BF(a3.im, a1.im, i1, t3);\
BF(t4, t6, t2, t6);\
BF(a3.re, a1.re, r1, t4);\
BF(a2.im, a0.im, i0, t6);\
}
#define TRANSFORM(a0,a1,a2,a3,wre,wim) {\
CMUL(t1, t2, a2.re, a2.im, wre, -wim);\
CMUL(t5, t6, a3.re, a3.im, wre, wim);\
BUTTERFLIES(a0,a1,a2,a3)\
}
#define TRANSFORM_ZERO(a0,a1,a2,a3) {\
t1 = a2.re;\
t2 = a2.im;\
t5 = a3.re;\
t6 = a3.im;\
BUTTERFLIES(a0,a1,a2,a3)\
}
/* z[0...8n-1], w[1...2n-1] */
#define PASS(name)\
static void name(FFTComplex *z, const FFTSample *wre, unsigned int n)\
{\
FFTSample t1, t2, t3, t4, t5, t6;\
int o1 = 2*n;\
int o2 = 4*n;\
int o3 = 6*n;\
const FFTSample *wim = wre+o1;\
n--;\
\
TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
do {\
z += 2;\
wre += 2;\
wim -= 2;\
TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
} while(--n);\
}
PASS(pass)
#undef BUTTERFLIES
#define BUTTERFLIES BUTTERFLIES_BIG
PASS(pass_big)
#define DECL_FFT(n,n2,n4)\
static void fft##n(FFTComplex *z)\
{\
fft##n2(z);\
fft##n4(z+n4*2);\
fft##n4(z+n4*3);\
pass(z,FFT_NAME(ff_cos_##n),n4/2);\
}
static void fft4(FFTComplex *z)
{
FFTSample t1, t2, t3, t4, t5, t6, t7, t8;
BF(t3, t1, z[0].re, z[1].re);
BF(t8, t6, z[3].re, z[2].re);
BF(z[2].re, z[0].re, t1, t6);
BF(t4, t2, z[0].im, z[1].im);
BF(t7, t5, z[2].im, z[3].im);
BF(z[3].im, z[1].im, t4, t8);
BF(z[3].re, z[1].re, t3, t7);
BF(z[2].im, z[0].im, t2, t5);
}
static void fft8(FFTComplex *z)
{
FFTSample t1, t2, t3, t4, t5, t6;
fft4(z);
BF(t1, z[5].re, z[4].re, -z[5].re);
BF(t2, z[5].im, z[4].im, -z[5].im);
BF(t5, z[7].re, z[6].re, -z[7].re);
BF(t6, z[7].im, z[6].im, -z[7].im);
BUTTERFLIES(z[0],z[2],z[4],z[6]);
TRANSFORM(z[1],z[3],z[5],z[7],M_SQRT1_2,M_SQRT1_2);
}
static void fft16(FFTComplex *z)
{
FFTSample t1, t2, t3, t4, t5, t6;
FFTSample cos_16_1 = FFT_NAME(ff_cos_16)[1];
FFTSample cos_16_3 = FFT_NAME(ff_cos_16)[3];
fft8(z);
fft4(z+8);
fft4(z+12);
TRANSFORM_ZERO(z[0],z[4],z[8],z[12]);
TRANSFORM(z[2],z[6],z[10],z[14],M_SQRT1_2,M_SQRT1_2);
TRANSFORM(z[1],z[5],z[9],z[13],cos_16_1,cos_16_3);
TRANSFORM(z[3],z[7],z[11],z[15],cos_16_3,cos_16_1);
}
DECL_FFT(32,16,8)
DECL_FFT(64,32,16)
DECL_FFT(128,64,32)
DECL_FFT(256,128,64)
DECL_FFT(512,256,128)
#define pass pass_big
DECL_FFT(1024,512,256)
DECL_FFT(2048,1024,512)
DECL_FFT(4096,2048,1024)
DECL_FFT(8192,4096,2048)
DECL_FFT(16384,8192,4096)
DECL_FFT(32768,16384,8192)
DECL_FFT(65536,32768,16384)
DECL_FFT(131072,65536,32768)
static void (* const fft_dispatch[])(FFTComplex*) = {
fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024,
fft2048, fft4096, fft8192, fft16384, fft32768, fft65536, fft131072
};
#define DECL_COMP_FFT(N) \
static void compound_fft_##N##xM(AVTXContext *s, void *_out, \
void *_in, ptrdiff_t stride) \
{ \
const int m = s->m, *in_map = s->pfatab, *out_map = in_map + N*m; \
FFTComplex *in = _in; \
FFTComplex *out = _out; \
FFTComplex fft##N##in[N]; \
void (*fftp)(FFTComplex *z) = fft_dispatch[av_log2(m) - 2]; \
\
for (int i = 0; i < m; i++) { \
for (int j = 0; j < N; j++) \
fft##N##in[j] = in[in_map[i*N + j]]; \
fft##N(s->tmp + s->revtab[i], fft##N##in, m); \
} \
\
for (int i = 0; i < N; i++) \
fftp(s->tmp + m*i); \
\
for (int i = 0; i < N*m; i++) \
out[i] = s->tmp[out_map[i]]; \
}
DECL_COMP_FFT(3)
DECL_COMP_FFT(5)
DECL_COMP_FFT(15)
static void monolithic_fft(AVTXContext *s, void *_out, void *_in,
ptrdiff_t stride)
{
FFTComplex *in = _in;
FFTComplex *out = _out;
int m = s->m, mb = av_log2(m) - 2;
for (int i = 0; i < m; i++)
out[s->revtab[i]] = in[i];
fft_dispatch[mb](out);
}
#define DECL_COMP_IMDCT(N) \
static void compound_imdct_##N##xM(AVTXContext *s, void *_dst, void *_src, \
ptrdiff_t stride) \
{ \
FFTComplex fft##N##in[N]; \
FFTComplex *z = _dst, *exp = s->exptab; \
const int m = s->m, len8 = N*m >> 1; \
const int *in_map = s->pfatab, *out_map = in_map + N*m; \
const float *src = _src, *in1, *in2; \
void (*fftp)(FFTComplex *) = fft_dispatch[av_log2(m) - 2]; \
\
stride /= sizeof(*src); /* To convert it from bytes */ \
in1 = src; \
in2 = src + ((N*m*2) - 1) * stride; \
\
for (int i = 0; i < m; i++) { \
for (int j = 0; j < N; j++) { \
const int k = in_map[i*N + j]; \
FFTComplex tmp = { in2[-k*stride], in1[k*stride] }; \
CMUL3(fft##N##in[j], tmp, exp[k >> 1]); \
} \
fft##N(s->tmp + s->revtab[i], fft##N##in, m); \
} \
\
for (int i = 0; i < N; i++) \
fftp(s->tmp + m*i); \
\
for (int i = 0; i < len8; i++) { \
const int i0 = len8 + i, i1 = len8 - i - 1; \
const int s0 = out_map[i0], s1 = out_map[i1]; \
FFTComplex src1 = { s->tmp[s1].im, s->tmp[s1].re }; \
FFTComplex src0 = { s->tmp[s0].im, s->tmp[s0].re }; \
\
CMUL(z[i1].re, z[i0].im, src1.re, src1.im, exp[i1].im, exp[i1].re); \
CMUL(z[i0].re, z[i1].im, src0.re, src0.im, exp[i0].im, exp[i0].re); \
} \
}
DECL_COMP_IMDCT(3)
DECL_COMP_IMDCT(5)
DECL_COMP_IMDCT(15)
#define DECL_COMP_MDCT(N) \
static void compound_mdct_##N##xM(AVTXContext *s, void *_dst, void *_src, \
ptrdiff_t stride) \
{ \
float *src = _src, *dst = _dst; \
FFTComplex *exp = s->exptab, tmp, fft##N##in[N]; \
const int m = s->m, len4 = N*m, len3 = len4 * 3, len8 = len4 >> 1; \
const int *in_map = s->pfatab, *out_map = in_map + N*m; \
void (*fftp)(FFTComplex *) = fft_dispatch[av_log2(m) - 2]; \
\
stride /= sizeof(*dst); \
\
for (int i = 0; i < m; i++) { /* Folding and pre-reindexing */ \
for (int j = 0; j < N; j++) { \
const int k = in_map[i*N + j]; \
if (k < len4) { \
tmp.re = -src[ len4 + k] + src[1*len4 - 1 - k]; \
tmp.im = -src[ len3 + k] - src[1*len3 - 1 - k]; \
} else { \
tmp.re = -src[ len4 + k] - src[5*len4 - 1 - k]; \
tmp.im = src[-len4 + k] - src[1*len3 - 1 - k]; \
} \
CMUL(fft##N##in[j].im, fft##N##in[j].re, tmp.re, tmp.im, \
exp[k >> 1].re, exp[k >> 1].im); \
} \
fft##N(s->tmp + s->revtab[i], fft##N##in, m); \
} \
\
for (int i = 0; i < N; i++) \
fftp(s->tmp + m*i); \
\
for (int i = 0; i < len8; i++) { \
const int i0 = len8 + i, i1 = len8 - i - 1; \
const int s0 = out_map[i0], s1 = out_map[i1]; \
FFTComplex src1 = { s->tmp[s1].re, s->tmp[s1].im }; \
FFTComplex src0 = { s->tmp[s0].re, s->tmp[s0].im }; \
\
CMUL(dst[2*i1*stride + stride], dst[2*i0*stride], src0.re, src0.im, \
exp[i0].im, exp[i0].re); \
CMUL(dst[2*i0*stride + stride], dst[2*i1*stride], src1.re, src1.im, \
exp[i1].im, exp[i1].re); \
} \
}
DECL_COMP_MDCT(3)
DECL_COMP_MDCT(5)
DECL_COMP_MDCT(15)
static void monolithic_imdct(AVTXContext *s, void *_dst, void *_src,
ptrdiff_t stride)
{
FFTComplex *z = _dst, *exp = s->exptab;
const int m = s->m, len8 = m >> 1;
const float *src = _src, *in1, *in2;
void (*fftp)(FFTComplex *) = fft_dispatch[av_log2(m) - 2];
stride /= sizeof(*src);
in1 = src;
in2 = src + ((m*2) - 1) * stride;
for (int i = 0; i < m; i++) {
FFTComplex tmp = { in2[-2*i*stride], in1[2*i*stride] };
CMUL3(z[s->revtab[i]], tmp, exp[i]);
}
fftp(z);
for (int i = 0; i < len8; i++) {
const int i0 = len8 + i, i1 = len8 - i - 1;
FFTComplex src1 = { z[i1].im, z[i1].re };
FFTComplex src0 = { z[i0].im, z[i0].re };
CMUL(z[i1].re, z[i0].im, src1.re, src1.im, exp[i1].im, exp[i1].re);
CMUL(z[i0].re, z[i1].im, src0.re, src0.im, exp[i0].im, exp[i0].re);
}
}
static void monolithic_mdct(AVTXContext *s, void *_dst, void *_src,
ptrdiff_t stride)
{
float *src = _src, *dst = _dst;
FFTComplex *exp = s->exptab, tmp, *z = _dst;
const int m = s->m, len4 = m, len3 = len4 * 3, len8 = len4 >> 1;
void (*fftp)(FFTComplex *) = fft_dispatch[av_log2(m) - 2];
stride /= sizeof(*dst);
for (int i = 0; i < m; i++) { /* Folding and pre-reindexing */
const int k = 2*i;
if (k < len4) {
tmp.re = -src[ len4 + k] + src[1*len4 - 1 - k];
tmp.im = -src[ len3 + k] - src[1*len3 - 1 - k];
} else {
tmp.re = -src[ len4 + k] - src[5*len4 - 1 - k];
tmp.im = src[-len4 + k] - src[1*len3 - 1 - k];
}
CMUL(z[s->revtab[i]].im, z[s->revtab[i]].re, tmp.re, tmp.im,
exp[i].re, exp[i].im);
}
fftp(z);
for (int i = 0; i < len8; i++) {
const int i0 = len8 + i, i1 = len8 - i - 1;
FFTComplex src1 = { z[i1].re, z[i1].im };
FFTComplex src0 = { z[i0].re, z[i0].im };
CMUL(dst[2*i1*stride + stride], dst[2*i0*stride], src0.re, src0.im,
exp[i0].im, exp[i0].re);
CMUL(dst[2*i0*stride + stride], dst[2*i1*stride], src1.re, src1.im,
exp[i1].im, exp[i1].re);
}
}
/* Calculates the modular multiplicative inverse, not fast, replace */
static int mulinv(int n, int m)
{
n = n % m;
for (int x = 1; x < m; x++)
if (((n * x) % m) == 1)
return x;
av_assert0(0); /* Never reached */
}
/* Guaranteed to work for any n, m where gcd(n, m) == 1 */
static int gen_compound_mapping(AVTXContext *s, int n, int m, int inv,
enum AVTXType type)
{
int *in_map, *out_map;
const int len = n*m;
const int m_inv = mulinv(m, n);
const int n_inv = mulinv(n, m);
const int mdct = type == AV_TX_FLOAT_MDCT;
if (!(s->pfatab = av_malloc(2*len*sizeof(*s->pfatab))))
return AVERROR(ENOMEM);
in_map = s->pfatab;
out_map = s->pfatab + n*m;
/* Ruritanian map for input, CRT map for output, can be swapped */
for (int j = 0; j < m; j++) {
for (int i = 0; i < n; i++) {
/* Shifted by 1 to simplify forward MDCTs */
in_map[j*n + i] = ((i*m + j*n) % len) << mdct;
out_map[(i*m*m_inv + j*n*n_inv) % len] = i*m + j;
}
}
/* Change transform direction by reversing all ACs */
if (inv) {
for (int i = 0; i < m; i++) {
int *in = &in_map[i*n + 1]; /* Skip the DC */
for (int j = 0; j < ((n - 1) >> 1); j++)
FFSWAP(int, in[j], in[n - j - 2]);
}
}
/* Our 15-point transform is also a compound one, so embed its input map */
if (n == 15) {
for (int k = 0; k < m; k++) {
int tmp[15];
memcpy(tmp, &in_map[k*15], 15*sizeof(*tmp));
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 3; j++)
in_map[k*15 + i*3 + j] = tmp[(i*3 + j*5) % 15];
}
}
}
return 0;
}
static int split_radix_permutation(int i, int n, int inverse)
{
int m;
if (n <= 2)
return i & 1;
m = n >> 1;
if (!(i & m))
return split_radix_permutation(i, m, inverse)*2;
m >>= 1;
if (inverse == !(i & m))
return split_radix_permutation(i, m, inverse)*4 + 1;
else
return split_radix_permutation(i, m, inverse)*4 - 1;
}
static int get_ptwo_revtab(AVTXContext *s, int m, int inv)
{
if (!(s->revtab = av_malloc(m*sizeof(*s->revtab))))
return AVERROR(ENOMEM);
/* Default */
for (int i = 0; i < m; i++) {
int k = -split_radix_permutation(i, m, inv) & (m - 1);
s->revtab[k] = i;
}
return 0;
}
static int gen_mdct_exptab(AVTXContext *s, int len4, double scale)
{
const double theta = (scale < 0 ? len4 : 0) + 1.0/8.0;
if (!(s->exptab = av_malloc_array(len4, sizeof(*s->exptab))))
return AVERROR(ENOMEM);
scale = sqrt(fabs(scale));
for (int i = 0; i < len4; i++) {
const double alpha = M_PI_2 * (i + theta) / len4;
s->exptab[i].re = cos(alpha) * scale;
s->exptab[i].im = sin(alpha) * scale;
}
return 0;
}
av_cold void av_tx_uninit(AVTXContext **ctx)
{
if (!(*ctx))
return;
av_free((*ctx)->pfatab);
av_free((*ctx)->exptab);
av_free((*ctx)->revtab);
av_free((*ctx)->tmp);
av_freep(ctx);
}
static int init_mdct_fft(AVTXContext *s, av_tx_fn *tx, enum AVTXType type,
int inv, int len, const void *scale, uint64_t flags)
{
int err, n = 1, m = 1, max_ptwo = 1 << (FF_ARRAY_ELEMS(fft_dispatch) + 1);
if (type == AV_TX_FLOAT_MDCT)
len >>= 1;
#define CHECK_FACTOR(DST, FACTOR, SRC) \
if (DST == 1 && !(SRC % FACTOR)) { \
DST = FACTOR; \
SRC /= FACTOR; \
}
CHECK_FACTOR(n, 15, len)
CHECK_FACTOR(n, 5, len)
CHECK_FACTOR(n, 3, len)
#undef CHECK_NPTWO_FACTOR
/* len must be a power of two now */
if (!(len & (len - 1)) && len >= 4 && len <= max_ptwo) {
m = len;
len = 1;
}
/* Filter out direct 3, 5 and 15 transforms, too niche */
if (len > 1 || m == 1) {
av_log(NULL, AV_LOG_ERROR, "Unsupported transform size: n = %i, "
"m = %i, residual = %i!\n", n, m, len);
return AVERROR(EINVAL);
} else if (n > 1 && m > 1) { /* 2D transform case */
if ((err = gen_compound_mapping(s, n, m, inv, type)))
return err;
if (!(s->tmp = av_malloc(n*m*sizeof(*s->tmp))))
return AVERROR(ENOMEM);
*tx = n == 3 ? compound_fft_3xM :
n == 5 ? compound_fft_5xM :
compound_fft_15xM;
if (type == AV_TX_FLOAT_MDCT)
*tx = n == 3 ? inv ? compound_imdct_3xM : compound_mdct_3xM :
n == 5 ? inv ? compound_imdct_5xM : compound_mdct_5xM :
inv ? compound_imdct_15xM : compound_mdct_15xM;
} else { /* Direct transform case */
*tx = monolithic_fft;
if (type == AV_TX_FLOAT_MDCT)
*tx = inv ? monolithic_imdct : monolithic_mdct;
}
if (n != 1)
ff_thread_once(&tabs_53_once, ff_init_53_tabs);
if (m != 1) {
get_ptwo_revtab(s, m, inv);
for (int i = 4; i <= av_log2(m); i++)
ff_init_ff_cos_tabs(i);
}
if (type == AV_TX_FLOAT_MDCT)
if ((err = gen_mdct_exptab(s, n*m, *((float *)scale))))
return err;
s->n = n;
s->m = m;
return 0;
}
av_cold int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
int inv, int len, const void *scale, uint64_t flags)
{
int err;
AVTXContext *s = av_mallocz(sizeof(*s));
if (!s)
return AVERROR(ENOMEM);
switch (type) {
case AV_TX_FLOAT_FFT:
case AV_TX_FLOAT_MDCT:
if ((err = init_mdct_fft(s, tx, type, inv, len, scale, flags)))
goto fail;
break;
default:
err = AVERROR(EINVAL);
goto fail;
}
*ctx = s;
return 0;
fail:
av_tx_uninit(&s);
*tx = NULL;
return err;
}
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