1 /* 2 * Linear conversion Plug-In 3 * Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org> 4 * 5 * 6 * This library is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU Library General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU Library General Public License for more details. 15 * 16 * You should have received a copy of the GNU Library General Public 17 * License along with this library; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 * 20 */ 21 22 #include <linux/time.h> 23 #include <sound/core.h> 24 #include <sound/pcm.h> 25 #include "pcm_plugin.h" 26 27 static snd_pcm_sframes_t copy_transfer(struct snd_pcm_plugin *plugin, 28 const struct snd_pcm_plugin_channel *src_channels, 29 struct snd_pcm_plugin_channel *dst_channels, 30 snd_pcm_uframes_t frames) 31 { 32 unsigned int channel; 33 unsigned int nchannels; 34 35 snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO); 36 if (frames == 0) 37 return 0; 38 nchannels = plugin->src_format.channels; 39 for (channel = 0; channel < nchannels; channel++) { 40 snd_assert(src_channels->area.first % 8 == 0 && 41 src_channels->area.step % 8 == 0, 42 return -ENXIO); 43 snd_assert(dst_channels->area.first % 8 == 0 && 44 dst_channels->area.step % 8 == 0, 45 return -ENXIO); 46 if (!src_channels->enabled) { 47 if (dst_channels->wanted) 48 snd_pcm_area_silence(&dst_channels->area, 0, frames, plugin->dst_format.format); 49 dst_channels->enabled = 0; 50 continue; 51 } 52 dst_channels->enabled = 1; 53 snd_pcm_area_copy(&src_channels->area, 0, &dst_channels->area, 0, frames, plugin->src_format.format); 54 src_channels++; 55 dst_channels++; 56 } 57 return frames; 58 } 59 60 int snd_pcm_plugin_build_copy(struct snd_pcm_substream *plug, 61 struct snd_pcm_plugin_format *src_format, 62 struct snd_pcm_plugin_format *dst_format, 63 struct snd_pcm_plugin **r_plugin) 64 { 65 int err; 66 struct snd_pcm_plugin *plugin; 67 int width; 68 69 snd_assert(r_plugin != NULL, return -ENXIO); 70 *r_plugin = NULL; 71 72 snd_assert(src_format->format == dst_format->format, return -ENXIO); 73 snd_assert(src_format->rate == dst_format->rate, return -ENXIO); 74 snd_assert(src_format->channels == dst_format->channels, return -ENXIO); 75 76 width = snd_pcm_format_physical_width(src_format->format); 77 snd_assert(width > 0, return -ENXIO); 78 79 err = snd_pcm_plugin_build(plug, "copy", src_format, dst_format, 80 0, &plugin); 81 if (err < 0) 82 return err; 83 plugin->transfer = copy_transfer; 84 *r_plugin = plugin; 85 return 0; 86 } 87