AOSP CL "pcm: add API for MMAP NO IRQ mode"

https://android.googlesource.com/platform/external/tinyalsa/+/5b15b4cbd9e779a4ecd87e0f757fb0f8f6b9bcb8

commit	5b15b4cbd9e779a4ecd87e0f757fb0f8f6b9bcb8
author	Eric Laurent <elaurent@google.com>

pcm: add API for MMAP NO IRQ mode

Bug: 33398120
Test: build
Change-Id: Iecb47f76337d98ceb01044ca488a04e1f350c6bc

1 files changed, 28 insertions, 0 deletions

diff --git a/src/pcm.c b/src/pcm.c
index eb16ed3..3b54ec7 100644
--- a/src/pcm.c
+++ b/src/pcm.c
@@ -1560,6 +1560,34 @@ int pcm_mmap_read(struct pcm *pcm, void *data, unsigned int count)
     return pcm_mmap_transfer(pcm, data, pcm_bytes_to_frames(pcm, count));
 }
 
+/* Returns current read/write position in the mmap buffer with associated time stamp. */
+int pcm_mmap_get_hw_ptr(struct pcm* pcm, unsigned int *hw_ptr, struct timespec *tstamp)
+{
+    int rc;
+
+    if (pcm == NULL || hw_ptr == NULL || tstamp == NULL)
+        return oops(pcm, EINVAL, "pcm %p, hw_ptr %p, tstamp %p", pcm, hw_ptr, tstamp);
+
+    if (!pcm_is_ready(pcm))
+        return oops(pcm, errno, "pcm_is_ready failed");
+
+    rc = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_HWSYNC);
+    if (rc < 0)
+        return oops(pcm, errno, "pcm_sync_ptr failed");
+
+    if ((pcm->mmap_status->state != PCM_STATE_RUNNING) &&
+            (pcm->mmap_status->state != PCM_STATE_DRAINING))
+        return oops(pcm, ENOSYS, "invalid stream state %d", pcm->mmap_status->state);
+
+    *tstamp = pcm->mmap_status->tstamp;
+    if (tstamp->tv_sec == 0 && tstamp->tv_nsec == 0)
+        return oops(pcm, errno, "invalid time stamp");
+
+    *hw_ptr = pcm->mmap_status->hw_ptr;
+
+    return 0;
+}
+
 static int pcm_rw_transfer(struct pcm *pcm, void *data, unsigned int frames)
 {
     int is_playback;