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DEFINITIONS
This source file includes following definitions.
- do_convert
- convert
- linear_transfer
- init_data
- snd_pcm_plugin_build_linear
/*
* Linear conversion Plug-In
* Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>,
* Abramo Bagnara <abramo@alsa-project.org>
*
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library 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 Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/time.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include "pcm_plugin.h"
/*
* Basic linear conversion plugin
*/
struct linear_priv {
int cvt_endian; /* need endian conversion? */
unsigned int src_ofs; /* byte offset in source format */
unsigned int dst_ofs; /* byte soffset in destination format */
unsigned int copy_ofs; /* byte offset in temporary u32 data */
unsigned int dst_bytes; /* byte size of destination format */
unsigned int copy_bytes; /* bytes to copy per conversion */
unsigned int flip; /* MSB flip for signeness, done after endian conv */
};
static inline void do_convert(struct linear_priv *data,
unsigned char *dst, unsigned char *src)
{
unsigned int tmp = 0;
unsigned char *p = (unsigned char *)&tmp;
memcpy(p + data->copy_ofs, src + data->src_ofs, data->copy_bytes);
if (data->cvt_endian)
tmp = swab32(tmp);
tmp ^= data->flip;
memcpy(dst, p + data->dst_ofs, data->dst_bytes);
}
static void convert(struct snd_pcm_plugin *plugin,
const struct snd_pcm_plugin_channel *src_channels,
struct snd_pcm_plugin_channel *dst_channels,
snd_pcm_uframes_t frames)
{
struct linear_priv *data = (struct linear_priv *)plugin->extra_data;
int channel;
int nchannels = plugin->src_format.channels;
for (channel = 0; channel < nchannels; ++channel) {
char *src;
char *dst;
int src_step, dst_step;
snd_pcm_uframes_t frames1;
if (!src_channels[channel].enabled) {
if (dst_channels[channel].wanted)
snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format);
dst_channels[channel].enabled = 0;
continue;
}
dst_channels[channel].enabled = 1;
src = src_channels[channel].area.addr + src_channels[channel].area.first / 8;
dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8;
src_step = src_channels[channel].area.step / 8;
dst_step = dst_channels[channel].area.step / 8;
frames1 = frames;
while (frames1-- > 0) {
do_convert(data, dst, src);
src += src_step;
dst += dst_step;
}
}
}
static snd_pcm_sframes_t linear_transfer(struct snd_pcm_plugin *plugin,
const struct snd_pcm_plugin_channel *src_channels,
struct snd_pcm_plugin_channel *dst_channels,
snd_pcm_uframes_t frames)
{
struct linear_priv *data;
if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
return -ENXIO;
data = (struct linear_priv *)plugin->extra_data;
if (frames == 0)
return 0;
#ifdef CONFIG_SND_DEBUG
{
unsigned int channel;
for (channel = 0; channel < plugin->src_format.channels; channel++) {
if (snd_BUG_ON(src_channels[channel].area.first % 8 ||
src_channels[channel].area.step % 8))
return -ENXIO;
if (snd_BUG_ON(dst_channels[channel].area.first % 8 ||
dst_channels[channel].area.step % 8))
return -ENXIO;
}
}
#endif
convert(plugin, src_channels, dst_channels, frames);
return frames;
}
static void init_data(struct linear_priv *data, int src_format, int dst_format)
{
int src_le, dst_le, src_bytes, dst_bytes;
src_bytes = snd_pcm_format_width(src_format) / 8;
dst_bytes = snd_pcm_format_width(dst_format) / 8;
src_le = snd_pcm_format_little_endian(src_format) > 0;
dst_le = snd_pcm_format_little_endian(dst_format) > 0;
data->dst_bytes = dst_bytes;
data->cvt_endian = src_le != dst_le;
data->copy_bytes = src_bytes < dst_bytes ? src_bytes : dst_bytes;
if (src_le) {
data->copy_ofs = 4 - data->copy_bytes;
data->src_ofs = src_bytes - data->copy_bytes;
} else
data->src_ofs = snd_pcm_format_physical_width(src_format) / 8 -
src_bytes;
if (dst_le)
data->dst_ofs = 4 - data->dst_bytes;
else
data->dst_ofs = snd_pcm_format_physical_width(dst_format) / 8 -
dst_bytes;
if (snd_pcm_format_signed(src_format) !=
snd_pcm_format_signed(dst_format)) {
if (dst_le)
data->flip = cpu_to_le32(0x80000000);
else
data->flip = cpu_to_be32(0x80000000);
}
}
int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug,
struct snd_pcm_plugin_format *src_format,
struct snd_pcm_plugin_format *dst_format,
struct snd_pcm_plugin **r_plugin)
{
int err;
struct linear_priv *data;
struct snd_pcm_plugin *plugin;
if (snd_BUG_ON(!r_plugin))
return -ENXIO;
*r_plugin = NULL;
if (snd_BUG_ON(src_format->rate != dst_format->rate))
return -ENXIO;
if (snd_BUG_ON(src_format->channels != dst_format->channels))
return -ENXIO;
if (snd_BUG_ON(!snd_pcm_format_linear(src_format->format) ||
!snd_pcm_format_linear(dst_format->format)))
return -ENXIO;
err = snd_pcm_plugin_build(plug, "linear format conversion",
src_format, dst_format,
sizeof(struct linear_priv), &plugin);
if (err < 0)
return err;
data = (struct linear_priv *)plugin->extra_data;
init_data(data, src_format->format, dst_format->format);
plugin->transfer = linear_transfer;
*r_plugin = plugin;
return 0;
}