/* * 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; } }