[alsa-devel] [PATCH - oss plugin update 2/2] oss: Add user variables to set period and buffer config
Takashi Iwai
tiwai at suse.de
Mon Jun 24 10:00:06 CEST 2013
At Sun, 23 Jun 2013 01:25:19 +0100,
alex.d.wiggins at gmail.com wrote:
>
> From: Alex Wiggins <alex.d.wiggins at 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 at 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
>
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