From 0b32bee3aa58705f7dc3c10486e8c7f1db7a9365 Mon Sep 17 00:00:00 2001
From: Ed <ed@xmos.com>
Date: Tue, 1 Sep 2020 09:55:53 +0100
Subject: [PATCH] Handle case at startup where decouple ISR gets stuck for
 several hundred cycles at startup, pushing out I2S timing

---
 lib_xua/src/core/buffer/decouple/decouple.xc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib_xua/src/core/buffer/decouple/decouple.xc b/lib_xua/src/core/buffer/decouple/decouple.xc
index 4e631dfb..f07f9411 100644
--- a/lib_xua/src/core/buffer/decouple/decouple.xc
+++ b/lib_xua/src/core/buffer/decouple/decouple.xc
@@ -523,6 +523,9 @@ __builtin_unreachable();
                     GET_SHARED_GLOBAL(rdPtr, g_aud_to_host_rdptr);
                     asm volatile("ldw %0, %1[0]":"=r"(datalength):"r"(rdPtr));
 
+                    /* Handle startup case where zero length packets exist */
+                    if(!datalength) break;
+
                     /* Round up datalength */
                     datalength = ((datalength+3) & ~0x3) + 4;