diff options
Diffstat (limited to 'sound/core/oss/linear.c')
| -rw-r--r-- | sound/core/oss/linear.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/sound/core/oss/linear.c b/sound/core/oss/linear.c new file mode 100644 index 00000000..2045697f --- /dev/null +++ b/sound/core/oss/linear.c @@ -0,0 +1,178 @@ +/* + * 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) +{ + if (snd_BUG_ON(!plugin || !src_channels || !dst_channels)) + return -ENXIO; + 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, + snd_pcm_format_t src_format, snd_pcm_format_t 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 = (__force u32)cpu_to_le32(0x80000000); + else + data->flip = (__force u32)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; +} |