sound/core/oss/linear.c

   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         struct linear_priv *data;
  94
  95         snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
  96         data = (struct linear_priv *)plugin->extra_data;
  97         if (frames == 0)
  98                 return 0;
  99 #ifdef CONFIG_SND_DEBUG
 100         {
 101                 unsigned int channel;
 102                 for (channel = 0; channel < plugin->src_format.channels; channel++) {
 103                         snd_assert(src_channels[channel].area.first % 8 == 0 &&
 104                                    src_channels[channel].area.step % 8 == 0,
 105                                    return -ENXIO);
 106                         snd_assert(dst_channels[channel].area.first % 8 == 0 &&
 107                                    dst_channels[channel].area.step % 8 == 0,
 108                                    return -ENXIO);
 109                 }
 110         }
 111 #endif
 112         convert(plugin, src_channels, dst_channels, frames);
 113         return frames;
 114 }
 115
 116 static void init_data(struct linear_priv *data, int src_format, int dst_format)
 117 {
 118         int src_le, dst_le, src_bytes, dst_bytes;
 119
 120         src_bytes = snd_pcm_format_width(src_format) / 8;
 121         dst_bytes = snd_pcm_format_width(dst_format) / 8;
 122         src_le = snd_pcm_format_little_endian(src_format) > 0;
 123         dst_le = snd_pcm_format_little_endian(dst_format) > 0;
 124
 125         data->dst_bytes = dst_bytes;
 126         data->cvt_endian = src_le != dst_le;
 127         data->copy_bytes = src_bytes < dst_bytes ? src_bytes : dst_bytes;
 128         if (src_le) {
 129                 data->copy_ofs = 4 - data->copy_bytes;
 130                 data->src_ofs = src_bytes - data->copy_bytes;
 131         } else
 132                 data->src_ofs = snd_pcm_format_physical_width(src_format) / 8 -
 133                         src_bytes;
 134         if (dst_le)
 135                 data->dst_ofs = 4 - data->dst_bytes;
 136         else
 137                 data->dst_ofs = snd_pcm_format_physical_width(dst_format) / 8 -
 138                         dst_bytes;
 139         if (snd_pcm_format_signed(src_format) !=
 140             snd_pcm_format_signed(dst_format)) {
 141                 if (dst_le)
 142                         data->flip = cpu_to_le32(0x80000000);
 143                 else
 144                         data->flip = cpu_to_be32(0x80000000);
 145         }
 146 }
 147
 148 int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug,
 149                                 struct snd_pcm_plugin_format *src_format,
 150                                 struct snd_pcm_plugin_format *dst_format,
 151                                 struct snd_pcm_plugin **r_plugin)
 152 {
 153         int err;
 154         struct linear_priv *data;
 155         struct snd_pcm_plugin *plugin;
 156
 157         snd_assert(r_plugin != NULL, return -ENXIO);
 158         *r_plugin = NULL;
 159
 160         snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
 161         snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
 162         snd_assert(snd_pcm_format_linear(src_format->format) &&
 163                    snd_pcm_format_linear(dst_format->format), return -ENXIO);
 164
 165         err = snd_pcm_plugin_build(plug, "linear format conversion",
 166                                    src_format, dst_format,
 167                                    sizeof(struct linear_priv), &plugin);
 168         if (err < 0)
 169                 return err;
 170         data = (struct linear_priv *)plugin->extra_data;
 171         init_data(data, src_format->format, dst_format->format);
 172         plugin->transfer = linear_transfer;
 173         *r_plugin = plugin;
 174         return 0;
 175 }