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FFmpeg/libavcodec/cbrt_tablegen.h
Ganesh Ajjanagadde 2f5075f551 avcodec/cbrt_tablegen: speed up dynamic table creation
On systems having cbrt, there is no reason to use the slow pow function.

Sample benchmark (x86-64, Haswell, GNU/Linux):
new:
5124920 decicycles in cbrt_tableinit,       1 runs,      0 skips

old:
12321680 decicycles in cbrt_tableinit,       1 runs,      0 skips

Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
2015-12-01 19:05:19 -05:00

65 lines
1.7 KiB
C

/*
* Header file for hardcoded AAC cube-root table
*
* Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
*
* 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_CBRT_TABLEGEN_H
#define AVCODEC_CBRT_TABLEGEN_H
#include <stdint.h>
#include <math.h>
#include "libavutil/attributes.h"
#include "libavcodec/aac_defines.h"
#if USE_FIXED
#define CBRT(x) lrint((x).f * 8192)
#else
#define CBRT(x) x.i
#endif
#if CONFIG_HARDCODED_TABLES
#if USE_FIXED
#define cbrt_tableinit_fixed()
#include "libavcodec/cbrt_fixed_tables.h"
#else
#define cbrt_tableinit()
#include "libavcodec/cbrt_tables.h"
#endif
#else
static uint32_t cbrt_tab[1 << 13];
static av_cold void AAC_RENAME(cbrt_tableinit)(void)
{
if (!cbrt_tab[(1<<13) - 1]) {
int i;
for (i = 0; i < 1<<13; i++) {
union {
float f;
uint32_t i;
} f;
f.f = cbrt(i) * i;
cbrt_tab[i] = CBRT(f);
}
}
}
#endif /* CONFIG_HARDCODED_TABLES */
#endif /* AVCODEC_CBRT_TABLEGEN_H */