Merge pull request #206 from dvdli/tinyalsa-fix-pcm

Fix compatible issue and refine null parameters checking 

1 files changed, 14 insertions, 10 deletions

diff --git a/src/pcm.c b/src/pcm.c
index 63ca65f..a97d325 100644
--- a/src/pcm.c
+++ b/src/pcm.c
@@ -623,6 +623,16 @@ static int pcm_sync_ptr(struct pcm *pcm, int flags)
     return 0;
 }
 
+int pcm_state(struct pcm *pcm)
+{
+    // Update the state only. Do not sync HW sync.
+    int err = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_APPL | SNDRV_PCM_SYNC_PTR_AVAIL_MIN);
+    if (err < 0)
+        return err;
+
+    return pcm->mmap_status->state;
+}
+
 static int pcm_hw_mmap_status(struct pcm *pcm)
 {
     if (pcm->sync_ptr)
@@ -1196,6 +1206,10 @@ int pcm_prepare(struct pcm *pcm)
  */
 int pcm_start(struct pcm *pcm)
 {
+    if (pcm_state(pcm) == PCM_STATE_SETUP && pcm_prepare(pcm) != 0) {
+        return -1;
+    }
+
     /* set appl_ptr and avail_min in kernel */
     if (pcm_sync_ptr(pcm, 0) < 0)
         return -1;
@@ -1409,16 +1423,6 @@ again:
     return 0;
 }
 
-int pcm_state(struct pcm *pcm)
-{
-    // Update the state only. Do not sync HW sync.
-    int err = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_APPL | SNDRV_PCM_SYNC_PTR_AVAIL_MIN);
-    if (err < 0)
-        return err;
-
-    return pcm->mmap_status->state;
-}
-
 /** Waits for frames to be available for read or write operations.
  * @param pcm A PCM handle.
  * @param timeout The maximum amount of time to wait for, in terms of milliseconds.