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[ALSA] Simplify the format conversion in PCM OSS emulation
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Simplify the format conversion code in PCM OSS emulation.
This patch also adds the support of 3bytes 24bit formats with linear
and mulaw, but they are not enabled in pcm_plugin.c yet.

Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Jaroslav Kysela <[email protected]>
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@tiwai @perexg
tiwai authored and perexg committed Oct 16, 2007
1 parent 887f9f0 commit 9390ec8
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Showing 3 changed files with 97 additions and 436 deletions.
80 changes: 49 additions & 31 deletions sound/core/oss/linear.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,19 +31,34 @@
*/

struct linear_priv {
int conv;
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)
{
#define CONV_LABELS
#include "plugin_ops.h"
#undef CONV_LABELS
struct linear_priv *data = (struct linear_priv *)plugin->extra_data;
void *conv = conv_labels[data->conv];
int channel;
int nchannels = plugin->src_format.channels;
for (channel = 0; channel < nchannels; ++channel) {
Expand All @@ -64,11 +79,7 @@ static void convert(struct snd_pcm_plugin *plugin,
dst_step = dst_channels[channel].area.step / 8;
frames1 = frames;
while (frames1-- > 0) {
goto *conv;
#define CONV_END after
#include "plugin_ops.h"
#undef CONV_END
after:
do_convert(data, dst, src);
src += src_step;
dst += dst_step;
}
Expand Down Expand Up @@ -103,29 +114,36 @@ static snd_pcm_sframes_t linear_transfer(struct snd_pcm_plugin *plugin,
return frames;
}

static int conv_index(int src_format, int dst_format)
static void init_data(struct linear_priv *data, int src_format, int dst_format)
{
int src_endian, dst_endian, sign, src_width, dst_width;
int src_le, dst_le, src_bytes, dst_bytes;

sign = (snd_pcm_format_signed(src_format) !=
snd_pcm_format_signed(dst_format));
#ifdef SNDRV_LITTLE_ENDIAN
src_endian = snd_pcm_format_big_endian(src_format);
dst_endian = snd_pcm_format_big_endian(dst_format);
#else
src_endian = snd_pcm_format_little_endian(src_format);
dst_endian = snd_pcm_format_little_endian(dst_format);
#endif

if (src_endian < 0)
src_endian = 0;
if (dst_endian < 0)
dst_endian = 0;
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;

src_width = snd_pcm_format_width(src_format) / 8 - 1;
dst_width = snd_pcm_format_width(dst_format) / 8 - 1;

return src_width * 32 + src_endian * 16 + sign * 8 + dst_width * 2 + dst_endian;
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,
Expand All @@ -151,7 +169,7 @@ int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug,
if (err < 0)
return err;
data = (struct linear_priv *)plugin->extra_data;
data->conv = conv_index(src_format->format, dst_format->format);
init_data(data, src_format->format, dst_format->format);
plugin->transfer = linear_transfer;
*r_plugin = plugin;
return 0;
Expand Down
83 changes: 48 additions & 35 deletions sound/core/oss/mulaw.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -146,19 +146,32 @@ typedef void (*mulaw_f)(struct snd_pcm_plugin *plugin,

struct mulaw_priv {
mulaw_f func;
int conv;
int cvt_endian; /* need endian conversion? */
unsigned int native_ofs; /* byte offset in native format */
unsigned int copy_ofs; /* byte offset in s16 format */
unsigned int native_bytes; /* byte size of the native format */
unsigned int copy_bytes; /* bytes to copy per conversion */
u16 flip; /* MSB flip for signedness, done after endian conversion */
};

static inline void cvt_s16_to_native(struct mulaw_priv *data,
unsigned char *dst, u16 sample)
{
sample ^= data->flip;
if (data->cvt_endian)
sample = swab16(sample);
if (data->native_bytes > data->copy_bytes)
memset(dst, 0, data->native_bytes);
memcpy(dst + data->native_ofs, (char *)&sample + data->copy_ofs,
data->copy_bytes);
}

static void mulaw_decode(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)
{
#define PUT_S16_LABELS
#include "plugin_ops.h"
#undef PUT_S16_LABELS
struct mulaw_priv *data = (struct mulaw_priv *)plugin->extra_data;
void *put = put_s16_labels[data->conv];
int channel;
int nchannels = plugin->src_format.channels;
for (channel = 0; channel < nchannels; ++channel) {
Expand All @@ -180,30 +193,33 @@ static void mulaw_decode(struct snd_pcm_plugin *plugin,
frames1 = frames;
while (frames1-- > 0) {
signed short sample = ulaw2linear(*src);
goto *put;
#define PUT_S16_END after
#include "plugin_ops.h"
#undef PUT_S16_END
after:
cvt_s16_to_native(data, dst, sample);
src += src_step;
dst += dst_step;
}
}
}

static inline signed short cvt_native_to_s16(struct mulaw_priv *data,
unsigned char *src)
{
u16 sample = 0;
memcpy((char *)&sample + data->copy_ofs, src + data->native_ofs,
data->copy_bytes);
if (data->cvt_endian)
sample = swab16(sample);
sample ^= data->flip;
return (signed short)sample;
}

static void mulaw_encode(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)
{
#define GET_S16_LABELS
#include "plugin_ops.h"
#undef GET_S16_LABELS
struct mulaw_priv *data = (struct mulaw_priv *)plugin->extra_data;
void *get = get_s16_labels[data->conv];
int channel;
int nchannels = plugin->src_format.channels;
signed short sample = 0;
for (channel = 0; channel < nchannels; ++channel) {
char *src;
char *dst;
Expand All @@ -222,11 +238,7 @@ static void mulaw_encode(struct snd_pcm_plugin *plugin,
dst_step = dst_channels[channel].area.step / 8;
frames1 = frames;
while (frames1-- > 0) {
goto *get;
#define GET_S16_END after
#include "plugin_ops.h"
#undef GET_S16_END
after:
signed short sample = cvt_native_to_s16(data, src);
*dst = linear2ulaw(sample);
src += src_step;
dst += dst_step;
Expand Down Expand Up @@ -262,23 +274,25 @@ static snd_pcm_sframes_t mulaw_transfer(struct snd_pcm_plugin *plugin,
return frames;
}

static int getput_index(int format)
static void init_data(struct mulaw_priv *data, int format)
{
int sign, width, endian;
sign = !snd_pcm_format_signed(format);
width = snd_pcm_format_width(format) / 8 - 1;
if (width < 0 || width > 3) {
snd_printk(KERN_ERR "snd-pcm-oss: invalid format %d\n", format);
width = 0;
}
#ifdef SNDRV_LITTLE_ENDIAN
endian = snd_pcm_format_big_endian(format);
data->cvt_endian = snd_pcm_format_big_endian(format) > 0;
#else
endian = snd_pcm_format_little_endian(format);
data->cvt_endian = snd_pcm_format_little_endian(format) > 0;
#endif
if (endian < 0)
endian = 0;
return width * 4 + endian * 2 + sign;
if (!snd_pcm_format_signed(format))
data->flip = 0x8000;
data->native_bytes = snd_pcm_format_physical_width(format) / 8;
data->copy_bytes = data->native_bytes < 2 ? 1 : 2;
if (snd_pcm_format_little_endian(format)) {
data->native_ofs = data->native_bytes - data->copy_bytes;
data->copy_ofs = 2 - data->copy_bytes;
} else {
/* S24 in 4bytes need an 1 byte offset */
data->native_ofs = data->native_bytes -
snd_pcm_format_width(format) / 8;
}
}

int snd_pcm_plugin_build_mulaw(struct snd_pcm_substream *plug,
Expand Down Expand Up @@ -319,8 +333,7 @@ int snd_pcm_plugin_build_mulaw(struct snd_pcm_substream *plug,
return err;
data = (struct mulaw_priv *)plugin->extra_data;
data->func = func;
data->conv = getput_index(format->format);
snd_assert(data->conv >= 0 && data->conv < 4*2*2, return -EINVAL);
init_data(data, format->format);
plugin->transfer = mulaw_transfer;
*r_plugin = plugin;
return 0;
Expand Down
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