Re: [alsa-devel] [PATCH - oss plugin update 2/2] oss: Add user variables to set period and buffer config - Alsa-devel - mailman.alsa-project.org

24 Jun 2013

At Sun, 23 Jun 2013 01:25:19 +0100,
alex.d.wiggins@gmail.com wrote:
...
From: Alex Wiggins alex.d.wiggins@gmail.com
Added 4 user variables to control the OSS period and buffer config:

period_size_allowany (boolean):
if not set then queries OSS for period size
(by using SNDCTL_DSP_GETBLKSIZE),
if set to true then allows any power of 2 period size;

I'd suggest to put an underscore between "allow" and "any".
Or, instead of adding a flag...
...

period_size (integer):
sets the OSS period size (SND_PCM_IOPLUG_HW_PERIOD_BYTES);

... handle allowany when period_size < 0, for example.
Takashi
...

periods (integer):
sets the number of OSS periods (SND_PCM_IOPLUG_HW_PERIODS);

buffer_size (integer):
sets the OSS buffer size (SND_PCM_IOPLUG_HW_BUFFER_BYTES).


Note that ALSA performs sanity checks to prevent conflicts.
Signed-off-by: Alex Wiggins alex.d.wiggins@gmail.com

diff --git a/oss/pcm_oss.c b/oss/pcm_oss.c
index 6d8dea4..7131e54 100644
--- a/oss/pcm_oss.c
+++ b/oss/pcm_oss.c
@@ -60,6 +60,13 @@ typedef struct snd_pcm_oss {
   unsigned int period_shift;
   unsigned int periods;
   unsigned int frame_bytes;

/* user variables set using ALSA config files */
/* included here as this snd_pcm_oss_t struct
  is stored in io->private_data */


int user_period_size_allowany;
long int user_period_size;
long int user_periods;
long int user_buffer_size;

} snd_pcm_oss_t;
static snd_pcm_sframes_t oss_write(snd_pcm_ioplug_t *io,
@@ -406,6 +413,7 @@ static int oss_hw_constraint(snd_pcm_oss_t *oss)
   unsigned int nchannels;
   unsigned int channel[6];
   /* period and buffer bytes must be power of two */

/* minimum: 2^8 = 256; maximum: 2^23 = 8388608 */
static const unsigned int bytes_list[] = {
1U<<8, 1U<<9, 1U<<10, 1U<<11, 1U<<12, 1U<<13, 1U<<14, 1U<<15,
1U<<16, 1U<<17, 1U<<18, 1U<<19, 1U<<20, 1U<<21, 1U<<22, 1U<<23

@@ -498,20 +506,96 @@ static int oss_hw_constraint(snd_pcm_oss_t *oss)
   if (err < 0)
   	return err;

/* period size (in power of two) */
err = snd_pcm_ioplug_set_param_list(io, SND_PCM_IOPLUG_HW_PERIOD_BYTES,
			    ARRAY_SIZE(bytes_list), bytes_list);


if (err < 0)
return err;


/* periods */
err = snd_pcm_ioplug_set_param_minmax(io, SND_PCM_IOPLUG_HW_PERIODS, 2, 1024);
if (err < 0)
return err;


/* buffer size (in power of two) */
err = snd_pcm_ioplug_set_param_list(io, SND_PCM_IOPLUG_HW_BUFFER_BYTES,
			    ARRAY_SIZE(bytes_list), bytes_list);


if (err < 0)
return err;




/* period and buffer sizes: default behaviour below is to
  query period size from OSS */



/* consider user set paramaters
  (period_size_allowany; period_size; periods; buffer_size) */


/* note: ALSA performs sanity checks
 to prevent conflicting parameters */



/* period_size_allowany and period_size */
if (oss->user_period_size_allowany) {
/* period_size_allowany flag set:


   allow any power of 2 period size */


err = snd_pcm_ioplug_set_param_list(io,


	SND_PCM_IOPLUG_HW_PERIOD_BYTES,


	ARRAY_SIZE(bytes_list), bytes_list);


if (err < 0)


	return err;


} else {
if (oss->user_period_size > 0) {


	/* period_size set to positive value:


	   use user set period size */


	const unsigned int user_period_size


	  = oss->user_period_size;


	err = snd_pcm_ioplug_set_param_list(io,


		SND_PCM_IOPLUG_HW_PERIOD_BYTES, 1,


		&user_period_size);


} else {


	/* query OSS for period size (called fragment size) */


	unsigned int fragsize;


	if (ioctl(oss->fd, SNDCTL_DSP_GETBLKSIZE, &fragsize)


		< 0)


		fprintf(stderr,



+"*** alsa-plugins-oss: error querying SNDCTL_DSP_GETBLKSIZE.\n");


	/* note: second query of SNDCTL_DSP_GETBLKSIZE


		 can give different result


		 (i.e. 4096 instead of 2048) */


	/* in oss_audio_core.c getblksize function,


	   4096 is the default return value:


	   so second time probably not reliable */



	/* period size (in power of two) */


	unsigned int x = fragsize;


	/* check if fragsize is a power of two */


	if ((x != 0) && ((x & (~x + 1)) == x))


		err = snd_pcm_ioplug_set_param_list(io,


			SND_PCM_IOPLUG_HW_PERIOD_BYTES,


			1, &fragsize);


	else


		err = snd_pcm_ioplug_set_param_list(io,


			SND_PCM_IOPLUG_HW_PERIOD_BYTES,


			ARRAY_SIZE(bytes_list), bytes_list);


	if (err < 0)


		return err;


}


}


/* periods (number of periods per buffer) */

if (oss->user_periods > 0) {

/* force number of periods to user set periods */


const unsigned int user_periods = oss->user_periods;


err = snd_pcm_ioplug_set_param_list(io,


	SND_PCM_IOPLUG_HW_PERIODS, 1, &user_periods);


if (err < 0)


	return err;


} else {

/* allow any number of periods between 2 and 1024 inclusive


  (ALSA can choose) */


err = snd_pcm_ioplug_set_param_minmax(io,


	SND_PCM_IOPLUG_HW_PERIODS, 2, 1024);


if (err < 0)


	return err;


}


/* buffer_size */

if (oss->user_buffer_size > 0) {

/* force buffer size to user set buffer_size */


const unsigned int user_buffer_size = oss->user_buffer_size;


err = snd_pcm_ioplug_set_param_list(io,


	SND_PCM_IOPLUG_HW_BUFFER_BYTES, 1, &user_buffer_size);


if (err < 0)


	return err;


} else {

/* buffer size (in power of two) */


err = snd_pcm_ioplug_set_param_list(io,


	SND_PCM_IOPLUG_HW_BUFFER_BYTES,


	ARRAY_SIZE(bytes_list), bytes_list);


if (err < 0)


	return err;


}
return 0;


}
@@ -556,6 +640,11 @@ SND_PCM_PLUGIN_DEFINE_FUNC(oss)
   const char *device = "/dev/dsp";
   int err;
   snd_pcm_oss_t *oss;

/* default values for user variables*/

int user_period_size_allowany = 0;

long int user_period_size = 0;

long int user_periods = 0;

long int user_buffer_size = 0;
snd_config_for_each(i, next, conf) {
snd_config_t *n = snd_config_iterator_entry(i);


@@ -571,6 +660,39 @@ SND_PCM_PLUGIN_DEFINE_FUNC(oss)
   		}
   		continue;
   	}


/* user variables */


if (strcmp(id, "period_size_allowany") == 0) {


	if (snd_config_get_bool(n) < 0) {


		SNDERR("Invalid type for %s", id);


		return -EINVAL;


	} else


		user_period_size_allowany =


			snd_config_get_bool(n);


	continue;


}


if (strcmp(id, "period_size") == 0) {


	if (snd_config_get_integer(n, &user_period_size) < 0) {


		SNDERR("Invalid type for %s", id);


		return -EINVAL;


	}


	continue;


}


if (strcmp(id, "periods") == 0) {


	if (snd_config_get_integer(n, &user_periods) < 0) {


		SNDERR("Invalid type for %s", id);


		return -EINVAL;


	}


	continue;


}


if (strcmp(id, "buffer_size") == 0) {


	if (snd_config_get_integer(n, &user_buffer_size) < 0) {


		SNDERR("Invalid type for %s", id);


		return -EINVAL;


	}


	continue;


}


SNDERR("Unknown field %s", id);
  return -EINVAL;
 }

@@ -595,6 +717,12 @@ SND_PCM_PLUGIN_DEFINE_FUNC(oss)
   	goto error;
   }

/* save user variables from ALSA config files */
oss->user_period_size_allowany = user_period_size_allowany;
oss->user_period_size = user_period_size;
oss->user_periods = user_periods;
oss->user_buffer_size = user_buffer_size;
oss->io.version = SND_PCM_IOPLUG_VERSION;
 oss->io.name = "ALSA <-> OSS PCM I/O Plugin";
 oss->io.poll_fd = oss->fd;

-- 
1.8.3.1

    

Re: [alsa-devel] [PATCH - oss plugin update 2/2] oss: Add user variables to set period and buffer config

Takashi Iwai

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