FFmpeg4/libavcodec/fft.h

/*
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
 *
 * 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
 */

#ifndef AVCODEC_FFT_H
#define AVCODEC_FFT_H

#ifndef FFT_FLOAT
#define FFT_FLOAT 1
#endif

#ifndef FFT_FIXED_32
#define FFT_FIXED_32 0
#endif

#include <stdint.h>
#include "config.h"
#include "libavutil/mem.h"

#if FFT_FLOAT

#include "avfft.h"

#define FFT_NAME(x) x

typedef float FFTDouble;

#else

#if FFT_FIXED_32

#define Q31(x) (int)((x)*2147483648.0 + 0.5)
#define FFT_NAME(x) x ## _fixed_32

typedef int32_t FFTSample;

#else /* FFT_FIXED_32 */

#define FFT_NAME(x) x ## _fixed

typedef int16_t FFTSample;

#endif /* FFT_FIXED_32 */

typedef struct FFTComplex {
    FFTSample re, im;
} FFTComplex;

typedef int    FFTDouble;
typedef struct FFTContext FFTContext;

#endif /* FFT_FLOAT */

typedef struct FFTDComplex {
    FFTDouble re, im;
} FFTDComplex;

/* FFT computation */

enum fft_permutation_type {
    FF_FFT_PERM_DEFAULT,
    FF_FFT_PERM_SWAP_LSBS,
    FF_FFT_PERM_AVX,
};

enum mdct_permutation_type {
    FF_MDCT_PERM_NONE,
    FF_MDCT_PERM_INTERLEAVE,
};

struct FFTContext {
    int nbits;
    int inverse;
    uint16_t *revtab;
    FFTComplex *tmp_buf;
    int mdct_size; /* size of MDCT (i.e. number of input data * 2) */
    int mdct_bits; /* n = 2^nbits */
    /* pre/post rotation tables */
    FFTSample *tcos;
    FFTSample *tsin;
    /**
     * Do the permutation needed BEFORE calling fft_calc().
     */
    void (*fft_permute)(struct FFTContext *s, FFTComplex *z);
    /**
     * Do a complex FFT with the parameters defined in ff_fft_init(). The
     * input data must be permuted before. No 1.0/sqrt(n) normalization is done.
     */
    void (*fft_calc)(struct FFTContext *s, FFTComplex *z);
    void (*imdct_calc)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
    void (*imdct_half)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
    void (*mdct_calc)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
    void (*mdct_calcw)(struct FFTContext *s, FFTDouble *output, const FFTSample *input);
    enum fft_permutation_type fft_permutation;
    enum mdct_permutation_type mdct_permutation;
    uint32_t *revtab32;
};

#if CONFIG_HARDCODED_TABLES
#define COSTABLE_CONST const
#else
#define COSTABLE_CONST
#endif

#define COSTABLE(size) \
    COSTABLE_CONST DECLARE_ALIGNED(32, FFTSample, FFT_NAME(ff_cos_##size))[size/2]

extern COSTABLE(16);
extern COSTABLE(32);
extern COSTABLE(64);
extern COSTABLE(128);
extern COSTABLE(256);
extern COSTABLE(512);
extern COSTABLE(1024);
extern COSTABLE(2048);
extern COSTABLE(4096);
extern COSTABLE(8192);
extern COSTABLE(16384);
extern COSTABLE(32768);
extern COSTABLE(65536);
extern COSTABLE(131072);
extern COSTABLE_CONST FFTSample* const FFT_NAME(ff_cos_tabs)[18];

#define ff_init_ff_cos_tabs FFT_NAME(ff_init_ff_cos_tabs)

/**
 * Initialize the cosine table in ff_cos_tabs[index]
 * @param index index in ff_cos_tabs array of the table to initialize
 */
void ff_init_ff_cos_tabs(int index);

#define ff_fft_init FFT_NAME(ff_fft_init)
#define ff_fft_end  FFT_NAME(ff_fft_end)

/**
 * Set up a complex FFT.
 * @param nbits           log2 of the length of the input array
 * @param inverse         if 0 perform the forward transform, if 1 perform the inverse
 */
int ff_fft_init(FFTContext *s, int nbits, int inverse);

void ff_fft_init_aarch64(FFTContext *s);
void ff_fft_init_x86(FFTContext *s);
void ff_fft_init_arm(FFTContext *s);
void ff_fft_init_mips(FFTContext *s);
void ff_fft_init_ppc(FFTContext *s);

void ff_fft_fixed_init_arm(FFTContext *s);

void ff_fft_end(FFTContext *s);

#define ff_mdct_init FFT_NAME(ff_mdct_init)
#define ff_mdct_end  FFT_NAME(ff_mdct_end)

int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale);
void ff_mdct_end(FFTContext *s);

#endif /* AVCODEC_FFT_H */