bswap: make generic implementation more compiler-friendly

With these changes, gcc 4.5 and later recognise it as a bswap
and use the proper instructions on ARM and x86.  On x86, the
16-bit bswap is recognised from gcc 4.1.

Signed-off-by: Mans Rullgard <mans@mansr.com>

1 files changed, 2 insertions, 11 deletions

diff --git a/libavutil/bswap.h b/libavutil/bswap.h
index 3657ccd402..8a350e1cd5 100644
--- a/libavutil/bswap.h
+++ b/libavutil/bswap.h
@@ -65,23 +65,14 @@ static av_always_inline av_const uint16_t av_bswap16(uint16_t x)
 #ifndef av_bswap32
 static av_always_inline av_const uint32_t av_bswap32(uint32_t x)
 {
-    x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
-    x= (x>>16) | (x<<16);
-    return x;
+    return AV_BSWAP32C(x);
 }
 #endif
 
 #ifndef av_bswap64
 static inline uint64_t av_const av_bswap64(uint64_t x)
 {
-    union {
-        uint64_t ll;
-        uint32_t l[2];
-    } w, r;
-    w.ll = x;
-    r.l[0] = av_bswap32 (w.l[1]);
-    r.l[1] = av_bswap32 (w.l[0]);
-    return r.ll;
+    return (uint64_t)av_bswap32(x) << 32 | av_bswap32(x >> 32);
 }
 #endif