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added doc on pcm_open and null checking pcm_is_ready

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This commit is contained in:
Taylor Holberton
2017-01-13 21:39:48 -08:00
parent e737183ffc
commit e123a65654
1 changed files with 20 additions and 8 deletions
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src/pcm.c
+20 -8
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@@ -364,8 +364,10 @@ static int pcm_sync_ptr(struct pcm *pcm, int flags)
{
if (pcm->sync_ptr) {
pcm->sync_ptr->flags = flags;
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SYNC_PTR, pcm->sync_ptr) < 0)
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SYNC_PTR, pcm->sync_ptr) < 0) {
oops(pcm, errno, "failed to sync mmap ptr");
return -1;
}
return 0;
}
return -1;
@@ -870,8 +872,10 @@ int pcm_close(struct pcm *pcm)
* - @ref PCM_NOIRQ
* - @ref PCM_MONOTONIC
* @param config The hardware and software parameters to open the PCM with.
* @returns On success, returns an initialized pcm, ready for reading or writing.
* On error, returns NULL.
* @returns A PCM structure.
* If an error occurs allocating memory for the PCM, NULL is returned.
* Otherwise, client code should check that the PCM opened properly by calling @ref pcm_is_ready.
* If @ref pcm_is_ready, check @ref pcm_get_error for more information.
* @ingroup libtinyalsa-pcm
*/
struct pcm *pcm_open_by_name(const char *name,
@@ -902,8 +906,10 @@ struct pcm *pcm_open_by_name(const char *name,
* - @ref PCM_NOIRQ
* - @ref PCM_MONOTONIC
* @param config The hardware and software parameters to open the PCM with.
* @returns On success, returns an initialized pcm, ready for reading or writing.
* On error, returns NULL.
* @returns A PCM structure.
* If an error occurs allocating memory for the PCM, NULL is returned.
* Otherwise, client code should check that the PCM opened properly by calling @ref pcm_is_ready.
* If @ref pcm_is_ready, check @ref pcm_get_error for more information.
* @ingroup libtinyalsa-pcm
*/
struct pcm *pcm_open(unsigned int card, unsigned int device,
@@ -1074,13 +1080,17 @@ fail_close:
/** Checks if a PCM file has been opened without error.
* @param pcm A PCM handle.
* @return If a PCM's file descriptor is not valid, it returns zero.
* May be NULL.
* @return If a PCM's file descriptor is not valid or the pointer is NULL, it returns zero.
* Otherwise, the function returns one.
* @ingroup libtinyalsa-pcm
*/
int pcm_is_ready(const struct pcm *pcm)
{
return pcm->fd >= 0;
if (pcm != NULL) {
return pcm->fd >= 0;
}
return 0;
}
/** Links two PCMs.
@@ -1249,8 +1259,10 @@ int pcm_mmap_commit(struct pcm *pcm, unsigned int offset, unsigned int frames)
/* update the application pointer in userspace and kernel */
pcm_mmap_appl_forward(pcm, frames);
ret = pcm_sync_ptr(pcm, 0);
if (ret != 0)
if (ret != 0){
printf("%d\n", ret);
return ret;
}
return frames;
}