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FFmpeg/libavutil/tx_priv.h
Lynne 8e94b7cff0
lavu/tx: invert permutation lookups
out[lut[i]] = in[i] lookups were 4.04 times(!) slower than
out[i] = in[lut[i]] lookups for an out-of-place FFT of length 4096.

The permutes remain unchanged for anything but out-of-place monolithic
FFT, as those benefit quite a lot from the current order (it means
there's only 1 lookup necessary to add to an offset, rather than
a full gather).

The code was based around non-power-of-two FFTs, so this wasn't
benchmarked early on.
2021-02-27 04:21:05 +01:00

162 lines
6.0 KiB
C

/*
* 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 AVUTIL_TX_PRIV_H
#define AVUTIL_TX_PRIV_H
#include "tx.h"
#include <stddef.h>
#include "thread.h"
#include "mem.h"
#include "mem_internal.h"
#include "avassert.h"
#include "attributes.h"
#ifdef TX_FLOAT
#define TX_NAME(x) x ## _float
#define SCALE_TYPE float
typedef float FFTSample;
typedef AVComplexFloat FFTComplex;
#elif defined(TX_DOUBLE)
#define TX_NAME(x) x ## _double
#define SCALE_TYPE double
typedef double FFTSample;
typedef AVComplexDouble FFTComplex;
#elif defined(TX_INT32)
#define TX_NAME(x) x ## _int32
#define SCALE_TYPE float
typedef int32_t FFTSample;
typedef AVComplexInt32 FFTComplex;
#else
typedef void FFTComplex;
#endif
#if defined(TX_FLOAT) || defined(TX_DOUBLE)
#define CMUL(dre, dim, are, aim, bre, bim) do { \
(dre) = (are) * (bre) - (aim) * (bim); \
(dim) = (are) * (bim) + (aim) * (bre); \
} while (0)
#define SMUL(dre, dim, are, aim, bre, bim) do { \
(dre) = (are) * (bre) - (aim) * (bim); \
(dim) = (are) * (bim) - (aim) * (bre); \
} while (0)
#define UNSCALE(x) (x)
#define RESCALE(x) (x)
#define FOLD(a, b) ((a) + (b))
#elif defined(TX_INT32)
/* Properly rounds the result */
#define CMUL(dre, dim, are, aim, bre, bim) do { \
int64_t accu; \
(accu) = (int64_t)(bre) * (are); \
(accu) -= (int64_t)(bim) * (aim); \
(dre) = (int)(((accu) + 0x40000000) >> 31); \
(accu) = (int64_t)(bim) * (are); \
(accu) += (int64_t)(bre) * (aim); \
(dim) = (int)(((accu) + 0x40000000) >> 31); \
} while (0)
#define SMUL(dre, dim, are, aim, bre, bim) do { \
int64_t accu; \
(accu) = (int64_t)(bre) * (are); \
(accu) -= (int64_t)(bim) * (aim); \
(dre) = (int)(((accu) + 0x40000000) >> 31); \
(accu) = (int64_t)(bim) * (are); \
(accu) -= (int64_t)(bre) * (aim); \
(dim) = (int)(((accu) + 0x40000000) >> 31); \
} while (0)
#define UNSCALE(x) ((double)x/2147483648.0)
#define RESCALE(x) (av_clip64(lrintf((x) * 2147483648.0), INT32_MIN, INT32_MAX))
#define FOLD(x, y) ((int)((x) + (unsigned)(y) + 32) >> 6)
#endif
#define BF(x, y, a, b) do { \
x = (a) - (b); \
y = (a) + (b); \
} while (0)
#define CMUL3(c, a, b) \
CMUL((c).re, (c).im, (a).re, (a).im, (b).re, (b).im)
#define COSTABLE(size) \
DECLARE_ALIGNED(32, FFTSample, TX_NAME(ff_cos_##size))[size/2]
/* Used by asm, reorder with care */
struct AVTXContext {
int n; /* Non-power-of-two part */
int m; /* Power-of-two part */
int inv; /* Is inverse */
int type; /* Type */
uint64_t flags; /* Flags */
double scale; /* Scale */
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 */
int *inplace_idx; /* Required indices to revtab for in-place transforms */
};
/* Shared functions */
int ff_tx_type_is_mdct(enum AVTXType type);
int ff_tx_gen_compound_mapping(AVTXContext *s);
int ff_tx_gen_ptwo_revtab(AVTXContext *s, int invert_lookup);
int ff_tx_gen_ptwo_inplace_revtab_idx(AVTXContext *s);
/* Also used by SIMD init */
static inline 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;
}
/* Templated functions */
int ff_tx_init_mdct_fft_float(AVTXContext *s, av_tx_fn *tx,
enum AVTXType type, int inv, int len,
const void *scale, uint64_t flags);
int ff_tx_init_mdct_fft_double(AVTXContext *s, av_tx_fn *tx,
enum AVTXType type, int inv, int len,
const void *scale, uint64_t flags);
int ff_tx_init_mdct_fft_int32(AVTXContext *s, av_tx_fn *tx,
enum AVTXType type, int inv, int len,
const void *scale, uint64_t flags);
typedef struct CosTabsInitOnce {
void (*func)(void);
AVOnce control;
} CosTabsInitOnce;
#endif /* AVUTIL_TX_PRIV_H */