ffmpeg/libavutil/tx_priv.h
Lynne ae66a9db7b
lavu/tx: optimize and simplify inverse MDCTs
Convert the input from a scatter to a gather instead,
which is faster and better for SIMD.
Also, add a pre-shuffled exptab version to avoid
gathering there at all. This doubles the exptab size,
but the speedup makes it worth it. In SIMD, the
exptab will likely be purged to a higher cache
anyway because of the FFT in the middle, and
the amount of loads stays identical.

For a 960-point inverse MDCT, the speedup is 10%.

This makes it possible to write sane and fast SIMD
versions of inverse MDCTs.
2022-08-16 01:22:38 +02:00

317 lines
14 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 "thread.h"
#include "mem_internal.h"
#include "attributes.h"
#ifdef TX_FLOAT
#define TX_TAB(x) x ## _float
#define TX_NAME(x) x ## _float_c
#define TX_NAME_STR(x) NULL_IF_CONFIG_SMALL(x "_float_c")
#define TX_TYPE(x) AV_TX_FLOAT_ ## x
#define TX_FN_NAME(fn, suffix) ff_tx_ ## fn ## _float_ ## suffix
#define TX_FN_NAME_STR(fn, suffix) NULL_IF_CONFIG_SMALL(#fn "_float_" #suffix)
#define MULT(x, m) ((x) * (m))
#define SCALE_TYPE float
typedef float TXSample;
typedef AVComplexFloat TXComplex;
#elif defined(TX_DOUBLE)
#define TX_TAB(x) x ## _double
#define TX_NAME(x) x ## _double_c
#define TX_NAME_STR(x) NULL_IF_CONFIG_SMALL(x "_double_c")
#define TX_TYPE(x) AV_TX_DOUBLE_ ## x
#define TX_FN_NAME(fn, suffix) ff_tx_ ## fn ## _double_ ## suffix
#define TX_FN_NAME_STR(fn, suffix) NULL_IF_CONFIG_SMALL(#fn "_double_" #suffix)
#define MULT(x, m) ((x) * (m))
#define SCALE_TYPE double
typedef double TXSample;
typedef AVComplexDouble TXComplex;
#elif defined(TX_INT32)
#define TX_TAB(x) x ## _int32
#define TX_NAME(x) x ## _int32_c
#define TX_NAME_STR(x) NULL_IF_CONFIG_SMALL(x "_int32_c")
#define TX_TYPE(x) AV_TX_INT32_ ## x
#define TX_FN_NAME(fn, suffix) ff_tx_ ## fn ## _int32_ ## suffix
#define TX_FN_NAME_STR(fn, suffix) NULL_IF_CONFIG_SMALL(#fn "_int32_" #suffix)
#define MULT(x, m) (((((int64_t)(x)) * (int64_t)(m)) + 0x40000000) >> 31)
#define SCALE_TYPE float
typedef int32_t TXSample;
typedef AVComplexInt32 TXComplex;
#else
typedef void TXComplex;
#endif
#define TX_DECL_FN(fn, suffix) \
void TX_FN_NAME(fn, suffix)(AVTXContext *s, void *o, void *i, ptrdiff_t st);
#define TX_DEF(fn, tx_type, len_min, len_max, f1, f2, \
p, init_fn, suffix, cf, cd_flags, cf2) \
&(const FFTXCodelet){ \
.name = TX_FN_NAME_STR(fn, suffix), \
.function = TX_FN_NAME(fn, suffix), \
.type = TX_TYPE(tx_type), \
.flags = FF_TX_ALIGNED | FF_TX_OUT_OF_PLACE | cd_flags, \
.factors = { f1, f2 }, \
.min_len = len_min, \
.max_len = len_max, \
.init = init_fn, \
.cpu_flags = cf2 | AV_CPU_FLAG_ ## cf, \
.prio = p, \
}
#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) ((int32_t)((x) + (unsigned)(y) + 32) >> 6)
#endif /* TX_INT32 */
#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)
/* Codelet flags, used to pick codelets. Must be a superset of enum AVTXFlags,
* but if it runs out of bits, it can be made separate. */
#define FF_TX_OUT_OF_PLACE (1ULL << 63) /* Can be OR'd with AV_TX_INPLACE */
#define FF_TX_ALIGNED (1ULL << 62) /* Cannot be OR'd with AV_TX_UNALIGNED */
#define FF_TX_PRESHUFFLE (1ULL << 61) /* Codelet expects permuted coeffs */
#define FF_TX_INVERSE_ONLY (1ULL << 60) /* For non-orthogonal inverse-only transforms */
#define FF_TX_FORWARD_ONLY (1ULL << 59) /* For non-orthogonal forward-only transforms */
typedef enum FFTXCodeletPriority {
FF_TX_PRIO_BASE = 0, /* Baseline priority */
/* For SIMD, set base prio to the register size in bits and increment in
* steps of 64 depending on faster/slower features, like FMA. */
FF_TX_PRIO_MIN = -131072, /* For naive implementations */
FF_TX_PRIO_MAX = 32768, /* For custom implementations/ASICs */
} FFTXCodeletPriority;
/* Codelet options */
typedef struct FFTXCodeletOptions {
int invert_lookup; /* If codelet is flagged as FF_TX_CODELET_PRESHUFFLE,
invert the lookup direction for the map generated */
} FFTXCodeletOptions;
/* Maximum amount of subtransform functions, subtransforms and factors. Arbitrary. */
#define TX_MAX_SUB 4
typedef struct FFTXCodelet {
const char *name; /* Codelet name, for debugging */
av_tx_fn function; /* Codelet function, != NULL */
enum AVTXType type; /* Type of codelet transform */
#define TX_TYPE_ANY INT32_MAX /* Special type to allow all types */
uint64_t flags; /* A combination of AVTXFlags and codelet
* flags that describe its properties. */
int factors[TX_MAX_SUB]; /* Length factors */
#define TX_FACTOR_ANY -1 /* When used alone, signals that the codelet
* supports all factors. Otherwise, if other
* factors are present, it signals that whatever
* remains will be supported, as long as the
* other factors are a component of the length */
int min_len; /* Minimum length of transform, must be >= 1 */
int max_len; /* Maximum length of transform */
#define TX_LEN_UNLIMITED -1 /* Special length value to permit all lengths */
int (*init)(AVTXContext *s, /* Optional callback for current context initialization. */
const struct FFTXCodelet *cd,
uint64_t flags,
FFTXCodeletOptions *opts,
int len, int inv,
const void *scale);
int (*uninit)(AVTXContext *s); /* Optional callback for uninitialization. */
int cpu_flags; /* CPU flags. If any negative flags like
* SLOW are present, will avoid picking.
* 0x0 to signal it's a C codelet */
#define FF_TX_CPU_FLAGS_ALL 0x0 /* Special CPU flag for C */
int prio; /* < 0 = least, 0 = no pref, > 0 = prefer */
} FFTXCodelet;
struct AVTXContext {
/* Fields the root transform and subtransforms use or may use.
* NOTE: This section is used by assembly, do not reorder or change */
int len; /* Length of the transform */
int inv; /* If transform is inverse */
int *map; /* Lookup table(s) */
TXComplex *exp; /* Any non-pre-baked multiplication factors needed */
TXComplex *tmp; /* Temporary buffer, if needed */
AVTXContext *sub; /* Subtransform context(s), if needed */
av_tx_fn fn[TX_MAX_SUB]; /* Function(s) for the subtransforms */
int nb_sub; /* Number of subtransforms.
* The reason all of these are set here
* rather than in each separate context
* is to eliminate extra pointer
* dereferences. */
/* Fields mainly useul/applicable for the root transform or initialization.
* Fields below are not used by assembly code. */
const FFTXCodelet *cd[TX_MAX_SUB]; /* Subtransform codelets */
const FFTXCodelet *cd_self; /* Codelet for the current context */
enum AVTXType type; /* Type of transform */
uint64_t flags; /* A combination of AVTXFlags and
* codelet flags used when creating */
float scale_f;
double scale_d;
void *opaque; /* Free to use by implementations */
};
/* Create a subtransform in the current context with the given parameters.
* The flags parameter from FFTXCodelet.init() should be preserved as much
* as that's possible.
* MUST be called during the sub() callback of each codelet. */
int ff_tx_init_subtx(AVTXContext *s, enum AVTXType type,
uint64_t flags, FFTXCodeletOptions *opts,
int len, int inv, const void *scale);
/*
* Generates the PFA permutation table into AVTXContext->pfatab. The end table
* is appended to the start table.
*/
int ff_tx_gen_compound_mapping(AVTXContext *s, int n, int m);
/*
* Generates a standard-ish (slightly modified) Split-Radix revtab into
* AVTXContext->map. Invert lookup changes how the mapping needs to be applied.
* If it's set to 0, it has to be applied like out[map[i]] = in[i], otherwise
* if it's set to 1, has to be applied as out[i] = in[map[i]]
*/
int ff_tx_gen_ptwo_revtab(AVTXContext *s, int invert_lookup);
/*
* Generates an index into AVTXContext->inplace_idx that if followed in the
* specific order, allows the revtab to be done in-place. The sub-transform
* and its map should already be initialized.
*/
int ff_tx_gen_ptwo_inplace_revtab_idx(AVTXContext *s);
/*
* This generates a parity-based revtab of length len and direction inv.
*
* Parity means even and odd complex numbers will be split, e.g. the even
* coefficients will come first, after which the odd coefficients will be
* placed. For example, a 4-point transform's coefficients after reordering:
* z[0].re, z[0].im, z[2].re, z[2].im, z[1].re, z[1].im, z[3].re, z[3].im
*
* The basis argument is the length of the largest non-composite transform
* supported, and also implies that the basis/2 transform is supported as well,
* as the split-radix algorithm requires it to be.
*
* The dual_stride argument indicates that both the basis, as well as the
* basis/2 transforms support doing two transforms at once, and the coefficients
* will be interleaved between each pair in a split-radix like so (stride == 2):
* tx1[0], tx1[2], tx2[0], tx2[2], tx1[1], tx1[3], tx2[1], tx2[3]
* A non-zero number switches this on, with the value indicating the stride
* (how many values of 1 transform to put first before switching to the other).
* Must be a power of two or 0. Must be less than the basis.
* Value will be clipped to the transform size, so for a basis of 16 and a
* dual_stride of 8, dual 8-point transforms will be laid out as if dual_stride
* was set to 4.
* Usually you'll set this to half the complex numbers that fit in a single
* register or 0. This allows to reuse SSE functions as dual-transform
* functions in AVX mode.
*
* If length is smaller than basis/2 this function will not do anything.
*/
int ff_tx_gen_split_radix_parity_revtab(AVTXContext *s, int invert_lookup,
int basis, int dual_stride);
/* Typed init function to initialize shared tables. Will initialize all tables
* for all factors of a length. */
void ff_tx_init_tabs_float (int len);
void ff_tx_init_tabs_double(int len);
void ff_tx_init_tabs_int32 (int len);
/* Typed init function to initialize an MDCT exptab in a context.
* If pre_tab is set, duplicates the entire table, with the first
* copy being shuffled according to pre_tab, and the second copy
* being the original. */
int ff_tx_mdct_gen_exp_float (AVTXContext *s, int *pre_tab);
int ff_tx_mdct_gen_exp_double(AVTXContext *s, int *pre_tab);
int ff_tx_mdct_gen_exp_int32 (AVTXContext *s, int *pre_tab);
/* Lists of codelets */
extern const FFTXCodelet * const ff_tx_codelet_list_float_c [];
extern const FFTXCodelet * const ff_tx_codelet_list_float_x86 [];
extern const FFTXCodelet * const ff_tx_codelet_list_double_c [];
extern const FFTXCodelet * const ff_tx_codelet_list_int32_c [];
#endif /* AVUTIL_TX_PRIV_H */