From 014773b66bdff4de24f384066d1a85d2a5bb6774 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Thu, 28 Jul 2016 14:30:25 +0300
Subject: [PATCH] libavutil: Use an intermediate variable in AV_COPY*U
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If AV_RN and AV_WN are macros with multiple individual reads and
writes, the previous version of the AV_COPYU macro would fail if
the reads and writes overlap.
This should not be any less efficient in any case, given a
sensibly optimizing compiler.
Signed-off-by: Martin Storsjö <martin@martin.st>
---
libavutil/intreadwrite.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/libavutil/intreadwrite.h b/libavutil/intreadwrite.h
index f77fd60f383..cdf1ef47ec7 100644
--- a/libavutil/intreadwrite.h
+++ b/libavutil/intreadwrite.h
@@ -467,7 +467,11 @@ union unaligned_16 { uint16_t l; } __attribute__((packed)) av_alias;
* memory locations.
*/
-#define AV_COPYU(n, d, s) AV_WN##n(d, AV_RN##n(s));
+#define AV_COPYU(n, d, s) \
+ do { \
+ uint##n##_t val = AV_RN##n(s); \
+ AV_WN##n(d, val); \
+ } while (0)
#ifndef AV_COPY16U
# define AV_COPY16U(d, s) AV_COPYU(16, d, s)
--
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