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Diffstat (limited to 'src/PcmVolume.cxx')
| -rw-r--r-- | src/PcmVolume.cxx | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/src/PcmVolume.cxx b/src/PcmVolume.cxx new file mode 100644 index 000000000..e19469f4a --- /dev/null +++ b/src/PcmVolume.cxx @@ -0,0 +1,194 @@ +/* + * Copyright (C) 2003-2011 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 "config.h" +#include "PcmVolume.hxx" +#include "PcmUtils.hxx" +#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, const int8_t *end, int volume) +{ + while (buffer < end) { + int32_t sample = *buffer; + + sample = (sample * volume + pcm_volume_dither() + + PCM_VOLUME_1 / 2) + / PCM_VOLUME_1; + + *buffer++ = pcm_range(sample, 8); + } +} + +static void +pcm_volume_change_16(int16_t *buffer, const int16_t *end, int volume) +{ + while (buffer < end) { + int32_t sample = *buffer; + + sample = (sample * volume + pcm_volume_dither() + + PCM_VOLUME_1 / 2) + / PCM_VOLUME_1; + + *buffer++ = pcm_range(sample, 16); + } +} + +#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, const int32_t *end, int volume) +{ + while (buffer < end) { +#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); + } +} + +static void +pcm_volume_change_32(int32_t *buffer, const int32_t *end, int volume) +{ + while (buffer < end) { +#ifdef __i386__ + /* assembly version for i386 */ + int32_t sample = *buffer; + + *buffer++ = pcm_volume_sample_24(sample, volume, 0); +#else + /* portable version */ + int64_t sample = *buffer; + + sample = (sample * volume + pcm_volume_dither() + + PCM_VOLUME_1 / 2) + / PCM_VOLUME_1; + *buffer++ = pcm_range_64(sample, 32); +#endif + } +} + +static void +pcm_volume_change_float(float *buffer, const float *end, float volume) +{ + while (buffer < end) { + float sample = *buffer; + sample *= volume; + *buffer++ = sample; + } +} + +bool +pcm_volume(void *buffer, size_t length, + enum sample_format format, + int volume) +{ + if (volume == PCM_VOLUME_1) + return true; + + if (volume <= 0) { + memset(buffer, 0, length); + return true; + } + + const void *end = pcm_end_pointer(buffer, length); + switch (format) { + case SAMPLE_FORMAT_UNDEFINED: + case SAMPLE_FORMAT_DSD: + /* not implemented */ + return false; + + case SAMPLE_FORMAT_S8: + pcm_volume_change_8((int8_t *)buffer, (const int8_t *)end, + volume); + return true; + + case SAMPLE_FORMAT_S16: + pcm_volume_change_16((int16_t *)buffer, (const int16_t *)end, + volume); + return true; + + case SAMPLE_FORMAT_S24_P32: + pcm_volume_change_24((int32_t *)buffer, (const int32_t *)end, + volume); + return true; + + case SAMPLE_FORMAT_S32: + pcm_volume_change_32((int32_t *)buffer, (const int32_t *)end, + volume); + return true; + + case SAMPLE_FORMAT_FLOAT: + pcm_volume_change_float((float *)buffer, (const float *)end, + pcm_volume_to_float(volume)); + return true; + } + + /* unreachable */ + assert(false); + return false; +} |