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/*
* Copyright (C) 2003-2009 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "pcm_volume.h"
#include "pcm_utils.h"
#include "audio_format.h"
#include <glib.h>
#include <stdint.h>
#include <string.h>
#undef G_LOG_DOMAIN
#define G_LOG_DOMAIN "pcm_volume"
static void
pcm_volume_change_8(int8_t *buffer, unsigned num_samples, int volume)
{
while (num_samples > 0) {
int32_t sample = *buffer;
sample = (sample * volume + pcm_volume_dither() +
PCM_VOLUME_1 / 2)
/ PCM_VOLUME_1;
*buffer++ = pcm_range(sample, 8);
--num_samples;
}
}
static void
pcm_volume_change_16(int16_t *buffer, unsigned num_samples, int volume)
{
while (num_samples > 0) {
int32_t sample = *buffer;
sample = (sample * volume + pcm_volume_dither() +
PCM_VOLUME_1 / 2)
/ PCM_VOLUME_1;
*buffer++ = pcm_range(sample, 16);
--num_samples;
}
}
#ifdef __i386__
/**
* Optimized volume function for i386. Use the EDX:EAX 2*32 bit
* multiplication result instead of emulating 64 bit multiplication.
*/
static inline int32_t
pcm_volume_sample_24(int32_t sample, int32_t volume, G_GNUC_UNUSED int32_t dither)
{
int32_t result;
asm(/* edx:eax = sample * volume */
"imul %2\n"
/* "add %3, %1\n" dithering disabled for now, because we
have no overflow check - is dithering really important
here? */
/* eax = edx:eax / PCM_VOLUME_1 */
"sal $22, %%edx\n"
"shr $10, %1\n"
"or %%edx, %1\n"
: "=a"(result)
: "0"(sample), "r"(volume) /* , "r"(dither) */
: "edx"
);
return result;
}
#endif
static void
pcm_volume_change_24(int32_t *buffer, unsigned num_samples, int volume)
{
while (num_samples > 0) {
#ifdef __i386__
/* assembly version for i386 */
int32_t sample = *buffer;
sample = pcm_volume_sample_24(sample, volume,
pcm_volume_dither());
#else
/* portable version */
int64_t sample = *buffer;
sample = (sample * volume + pcm_volume_dither() +
PCM_VOLUME_1 / 2)
/ PCM_VOLUME_1;
#endif
*buffer++ = pcm_range(sample, 24);
--num_samples;
}
}
bool
pcm_volume(void *buffer, int length,
const struct audio_format *format,
int volume)
{
if (volume == PCM_VOLUME_1)
return true;
if (volume <= 0) {
memset(buffer, 0, length);
return true;
}
switch (format->bits) {
case 8:
pcm_volume_change_8((int8_t *)buffer, length, volume);
return true;
case 16:
pcm_volume_change_16((int16_t *)buffer, length / 2,
volume);
return true;
case 24:
pcm_volume_change_24((int32_t*)buffer, length / 4,
volume);
return true;
default:
return false;
}
}
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