1 /* 2 * Linear conversion Plug-In 3 * Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>, 4 * Abramo Bagnara <abramo@alsa-project.org> 5 * 6 * 7 * This library is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU Library General Public License as 9 * published by the Free Software Foundation; either version 2 of 10 * the License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU Library General Public License for more details. 16 * 17 * You should have received a copy of the GNU Library General Public 18 * License along with this library; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 * 21 */ 22 23 #include <linux/time.h> 24 #include <sound/core.h> 25 #include <sound/pcm.h> 26 #include "pcm_plugin.h" 27 28 /* 29 * Basic linear conversion plugin 30 */ 31 32 struct linear_priv { 33 int cvt_endian; /* need endian conversion? */ 34 unsigned int src_ofs; /* byte offset in source format */ 35 unsigned int dst_ofs; /* byte soffset in destination format */ 36 unsigned int copy_ofs; /* byte offset in temporary u32 data */ 37 unsigned int dst_bytes; /* byte size of destination format */ 38 unsigned int copy_bytes; /* bytes to copy per conversion */ 39 unsigned int flip; /* MSB flip for signeness, done after endian conv */ 40 }; 41 42 static inline void do_convert(struct linear_priv *data, 43 unsigned char *dst, unsigned char *src) 44 { 45 unsigned int tmp = 0; 46 unsigned char *p = (unsigned char *)&tmp; 47 48 memcpy(p + data->copy_ofs, src + data->src_ofs, data->copy_bytes); 49 if (data->cvt_endian) 50 tmp = swab32(tmp); 51 tmp ^= data->flip; 52 memcpy(dst, p + data->dst_ofs, data->dst_bytes); 53 } 54 55 static void convert(struct snd_pcm_plugin *plugin, 56 const struct snd_pcm_plugin_channel *src_channels, 57 struct snd_pcm_plugin_channel *dst_channels, 58 snd_pcm_uframes_t frames) 59 { 60 struct linear_priv *data = (struct linear_priv *)plugin->extra_data; 61 int channel; 62 int nchannels = plugin->src_format.channels; 63 for (channel = 0; channel < nchannels; ++channel) { 64 char *src; 65 char *dst; 66 int src_step, dst_step; 67 snd_pcm_uframes_t frames1; 68 if (!src_channels[channel].enabled) { 69 if (dst_channels[channel].wanted) 70 snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format); 71 dst_channels[channel].enabled = 0; 72 continue; 73 } 74 dst_channels[channel].enabled = 1; 75 src = src_channels[channel].area.addr + src_channels[channel].area.first / 8; 76 dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8; 77 src_step = src_channels[channel].area.step / 8; 78 dst_step = dst_channels[channel].area.step / 8; 79 frames1 = frames; 80 while (frames1-- > 0) { 81 do_convert(data, dst, src); 82 src += src_step; 83 dst += dst_step; 84 } 85 } 86 } 87 88 static snd_pcm_sframes_t linear_transfer(struct snd_pcm_plugin *plugin, 89 const struct snd_pcm_plugin_channel *src_channels, 90 struct snd_pcm_plugin_channel *dst_channels, 91 snd_pcm_uframes_t frames) 92 { 93 if (snd_BUG_ON(!plugin || !src_channels || !dst_channels)) 94 return -ENXIO; 95 if (frames == 0) 96 return 0; 97 #ifdef CONFIG_SND_DEBUG 98 { 99 unsigned int channel; 100 for (channel = 0; channel < plugin->src_format.channels; channel++) { 101 if (snd_BUG_ON(src_channels[channel].area.first % 8 || 102 src_channels[channel].area.step % 8)) 103 return -ENXIO; 104 if (snd_BUG_ON(dst_channels[channel].area.first % 8 || 105 dst_channels[channel].area.step % 8)) 106 return -ENXIO; 107 } 108 } 109 #endif 110 if (frames > dst_channels[0].frames) 111 frames = dst_channels[0].frames; 112 convert(plugin, src_channels, dst_channels, frames); 113 return frames; 114 } 115 116 static void init_data(struct linear_priv *data, 117 snd_pcm_format_t src_format, snd_pcm_format_t dst_format) 118 { 119 int src_le, dst_le, src_bytes, dst_bytes; 120 121 src_bytes = snd_pcm_format_width(src_format) / 8; 122 dst_bytes = snd_pcm_format_width(dst_format) / 8; 123 src_le = snd_pcm_format_little_endian(src_format) > 0; 124 dst_le = snd_pcm_format_little_endian(dst_format) > 0; 125 126 data->dst_bytes = dst_bytes; 127 data->cvt_endian = src_le != dst_le; 128 data->copy_bytes = src_bytes < dst_bytes ? src_bytes : dst_bytes; 129 if (src_le) { 130 data->copy_ofs = 4 - data->copy_bytes; 131 data->src_ofs = src_bytes - data->copy_bytes; 132 } else 133 data->src_ofs = snd_pcm_format_physical_width(src_format) / 8 - 134 src_bytes; 135 if (dst_le) 136 data->dst_ofs = 4 - data->dst_bytes; 137 else 138 data->dst_ofs = snd_pcm_format_physical_width(dst_format) / 8 - 139 dst_bytes; 140 if (snd_pcm_format_signed(src_format) != 141 snd_pcm_format_signed(dst_format)) { 142 if (dst_le) 143 data->flip = (__force u32)cpu_to_le32(0x80000000); 144 else 145 data->flip = (__force u32)cpu_to_be32(0x80000000); 146 } 147 } 148 149 int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug, 150 struct snd_pcm_plugin_format *src_format, 151 struct snd_pcm_plugin_format *dst_format, 152 struct snd_pcm_plugin **r_plugin) 153 { 154 int err; 155 struct linear_priv *data; 156 struct snd_pcm_plugin *plugin; 157 158 if (snd_BUG_ON(!r_plugin)) 159 return -ENXIO; 160 *r_plugin = NULL; 161 162 if (snd_BUG_ON(src_format->rate != dst_format->rate)) 163 return -ENXIO; 164 if (snd_BUG_ON(src_format->channels != dst_format->channels)) 165 return -ENXIO; 166 if (snd_BUG_ON(!snd_pcm_format_linear(src_format->format) || 167 !snd_pcm_format_linear(dst_format->format))) 168 return -ENXIO; 169 170 err = snd_pcm_plugin_build(plug, "linear format conversion", 171 src_format, dst_format, 172 sizeof(struct linear_priv), &plugin); 173 if (err < 0) 174 return err; 175 data = (struct linear_priv *)plugin->extra_data; 176 init_data(data, src_format->format, dst_format->format); 177 plugin->transfer = linear_transfer; 178 *r_plugin = plugin; 179 return 0; 180 } 181