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

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