* [PATCH - oss plugin update revised 2/2] oss: Add user variables to set period and buffer config
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@ 2013-06-30 0:47 ` alex.d.wiggins
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From: alex.d.wiggins @ 2013-06-30 0:47 UTC (permalink / raw)
To: patch; +Cc: Alex Wiggins, alsa-devel
From: Alex Wiggins <alex.d.wiggins@gmail.com>
Added 3 user variables to control the OSS period and buffer config:
- period_size (integer):
if not set then queries OSS for period size
(by using SNDCTL_DSP_GETBLKSIZE),
if positive then sets the OSS period size
(SND_PCM_IOPLUG_HW_PERIOD_BYTES),
if negative then allows any power of 2 period size.
- 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 d5b5bc4..a92c3e9 100644
--- a/oss/pcm_oss.c
+++ b/oss/pcm_oss.c
@@ -60,6 +60,12 @@ 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 */
+ 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,
@@ -408,6 +414,7 @@ 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
@@ -500,20 +507,97 @@ 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; periods; buffer_size) */
+
+ /* note: ALSA performs sanity checks
+ to prevent conflicting parameters */
+
+ /* period_size */
+ if (oss->user_period_size < 0) {
+ /* period_size set to negative value:
+ 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;
}
@@ -558,6 +642,10 @@ SND_PCM_PLUGIN_DEFINE_FUNC(oss)
const char *device = "/dev/dsp";
int err;
snd_pcm_oss_t *oss;
+ /* default values for user variables*/
+ 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);
@@ -573,6 +661,30 @@ SND_PCM_PLUGIN_DEFINE_FUNC(oss)
}
continue;
}
+
+ /* user variables */
+ 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;
}
@@ -597,6 +709,11 @@ SND_PCM_PLUGIN_DEFINE_FUNC(oss)
goto error;
}
+ /* save user variables from ALSA config files */
+ 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
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