From 6a97f6a327134e83b7e1722dfe61fcb7f594b655 Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Mon, 28 Nov 2011 10:24:24 -0800
Subject: [PATCH] Reset the ALSA device if the number of available samples
 grows too large

---
 Alc/backends/alsa.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/Alc/backends/alsa.c b/Alc/backends/alsa.c
index 85e1d802..362b25da 100644
--- a/Alc/backends/alsa.c
+++ b/Alc/backends/alsa.c
@@ -70,6 +70,7 @@ MAKE_FUNC(snd_pcm_sw_params_free);
 MAKE_FUNC(snd_pcm_prepare);
 MAKE_FUNC(snd_pcm_start);
 MAKE_FUNC(snd_pcm_resume);
+MAKE_FUNC(snd_pcm_reset);
 MAKE_FUNC(snd_pcm_wait);
 MAKE_FUNC(snd_pcm_state);
 MAKE_FUNC(snd_pcm_avail_update);
@@ -133,6 +134,7 @@ MAKE_FUNC(snd_card_next);
 #define snd_pcm_prepare psnd_pcm_prepare
 #define snd_pcm_start psnd_pcm_start
 #define snd_pcm_resume psnd_pcm_resume
+#define snd_pcm_reset psnd_pcm_reset
 #define snd_pcm_wait psnd_pcm_wait
 #define snd_pcm_state psnd_pcm_state
 #define snd_pcm_avail_update psnd_pcm_avail_update
@@ -214,6 +216,7 @@ static ALCboolean alsa_load(void)
         LOAD_FUNC(snd_pcm_prepare);
         LOAD_FUNC(snd_pcm_start);
         LOAD_FUNC(snd_pcm_resume);
+        LOAD_FUNC(snd_pcm_reset);
         LOAD_FUNC(snd_pcm_wait);
         LOAD_FUNC(snd_pcm_state);
         LOAD_FUNC(snd_pcm_avail_update);
@@ -397,6 +400,7 @@ static ALuint ALSAProc(ALvoid *ptr)
     ALCdevice *pDevice = (ALCdevice*)ptr;
     alsa_data *data = (alsa_data*)pDevice->ExtraData;
     const snd_pcm_channel_area_t *areas = NULL;
+    snd_pcm_uframes_t update_size, num_updates;
     snd_pcm_sframes_t avail, commitres;
     snd_pcm_uframes_t offset, frames;
     char *WritePtr;
@@ -404,6 +408,8 @@ static ALuint ALSAProc(ALvoid *ptr)
 
     SetRTPriority();
 
+    update_size = pDevice->UpdateSize;
+    num_updates = pDevice->NumUpdates;
     while(!data->killNow)
     {
         int state = verify_state(data->pcmHandle);
@@ -421,8 +427,15 @@ static ALuint ALSAProc(ALvoid *ptr)
             continue;
         }
 
+        if((snd_pcm_uframes_t)avail > update_size*(num_updates+1))
+        {
+            WARN("available samples exceeds the buffer size\n");
+            snd_pcm_reset(data->pcmHandle);
+            continue;
+        }
+
         // make sure there's frames to process
-        if((snd_pcm_uframes_t)avail < pDevice->UpdateSize)
+        if((snd_pcm_uframes_t)avail < update_size)
         {
             if(state != SND_PCM_STATE_RUNNING)
             {
@@ -437,7 +450,7 @@ static ALuint ALSAProc(ALvoid *ptr)
                 ERR("Wait timeout... buffer size too low?\n");
             continue;
         }
-        avail -= avail%pDevice->UpdateSize;
+        avail -= avail%update_size;
 
         // it is possible that contiguous areas are smaller, thus we use a loop
         while(avail > 0)
-- 
2.11.4.GIT