make OSS detect blocking, adjust audio API

[picodrive.git] / platform / linux / sndout_oss.c

diff --git a/platform/linux/sndout_oss.c b/platform/linux/sndout_oss.c
index f9cc6c2..2313d3f 100644 (file)
--- a/platform/linux/sndout_oss.c
+++ b/platform/linux/sndout_oss.c
@@ -98,6 +98,42 @@ int sndout_oss_write(const void *buff, int len)
        return write(sounddev, buff, len);
 }
 
+#include "../common/plat.h"
+
+/* not really non-blocking, just detects if blocking occurs
+ * and starts skipping writes in case it does. */
+int sndout_oss_write_nb(const void *buff, int len)
+{
+       static int lag_counter, skip_counter;
+       unsigned int t;
+       int ret;
+
+       if (lag_counter > 2) {
+               // skip writes if audio starts blocking
+               lag_counter = 0;
+               skip_counter = FRAG_COUNT;
+       }
+
+       if (skip_counter > 0) {
+               skip_counter--;
+               return len;
+       }
+
+       t = plat_get_ticks_ms();
+       ret = sndout_oss_write(buff, len);
+       t = plat_get_ticks_ms() - t;
+       if (t > 1) {
+               // this shouldn't really happen, most likely audio is out of sync
+               lag_counter++;
+               if (lag_counter > 2)
+                       printf("audio lag %u\n", t);
+       }
+       else
+               lag_counter = 0;
+
+       return ret;
+}
+
 int sndout_oss_can_write(int bytes)
 {
        audio_buf_info bi;