added doc on pcm_open and null checking pcm_is_ready
diff --git a/src/pcm.c b/src/pcm.c
index 62e8d40..75fc85c 100644
--- a/src/pcm.c
+++ b/src/pcm.c
@@ -364,8 +364,10 @@
{
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 @@
* - @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 @@
* - @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 @@
/** 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 @@
/* 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;
}