[vlc-commits] Improve byte order inline functions
Rémi Denis-Courmont
git at videolan.org
Wed Aug 17 18:07:39 CEST 2011
vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Wed Aug 17 19:01:17 2011 +0300| [9ff7bdc46882335bd4ead9f9b5d252b6cb3863f7] | committer: Rémi Denis-Courmont
Improve byte order inline functions
* Use GCC built-ins for 32-bits and 64-bits byte swap where available.
* Load/store with single memcpy() instead of many byte operations.
* Do not use bits operations for the local byte order.
* Do not use reserved C keywords with leading underscores.
> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=9ff7bdc46882335bd4ead9f9b5d252b6cb3863f7
---
include/vlc_common.h | 213 +++++++++++++++++++++++++++++++------------------
1 files changed, 135 insertions(+), 78 deletions(-)
diff --git a/include/vlc_common.h b/include/vlc_common.h
index 337fd8a..9e49c35 100644
--- a/include/vlc_common.h
+++ b/include/vlc_common.h
@@ -630,6 +630,46 @@ static inline unsigned popcount (unsigned x)
#endif
}
+/** Byte swap (16 bits) */
+VLC_USED
+static inline uint16_t bswap16 (uint16_t x)
+{
+ return (x << 8) | (x >> 8);
+}
+
+/** Byte swap (32 bits) */
+VLC_USED
+static inline uint32_t bswap32 (uint32_t x)
+{
+#if VLC_GCC_VERSION(4,3)
+ return __builtin_bswap32 (x);
+#else
+ return ((x & 0x000000FF) << 24)
+ | ((x & 0x0000FF00) << 8)
+ | ((x & 0x00FF0000) >> 8)
+ | ((x & 0xFF000000) >> 24);
+#endif
+}
+
+/** Byte swap (64 bits) */
+VLC_USED
+static inline uint64_t bswap64 (uint64_t x)
+{
+#if VLC_GCC_VERSION(4,3)
+ return __builtin_bswap64 (x);
+#else
+ return ((x & 0x00000000000000FF) << 56)
+ | ((x & 0x000000000000FF00) << 40)
+ | ((x & 0x0000000000FF0000) << 24)
+ | ((x & 0x00000000FF000000) << 8)
+ | ((x & 0x000000FF00000000) >> 8)
+ | ((x & 0x0000FF0000000000) >> 24)
+ | ((x & 0x00FF000000000000) >> 40)
+ | ((x & 0xFF00000000000000) >> 56);
+#endif
+}
+
+
/* Free and set set the variable to NULL */
#define FREENULL(a) do { free( a ); a = NULL; } while(0)
@@ -641,123 +681,140 @@ VLC_API char const * vlc_error( int ) VLC_USED;
/* MSB (big endian)/LSB (little endian) conversions - network order is always
* MSB, and should be used for both network communications and files. */
+
+#ifdef WORDS_BIGENDIAN
+# define hton16(i) ((uint16_t)(i))
+# define hton32(i) ((uint32_t)(i))
+# define hton64(i) ((uint32_t)(i))
+#else
+# define hton16(i) bswap16(i)
+# define hton32(i) bswap32(i)
+# define hton64(i) bswap64(i)
+#endif
+#define ntoh16(i) hton16(i)
+#define ntoh32(i) hton32(i)
+#define ntoh64(i) hton64(i)
+
+/** Reads 16 bits in network byte order */
VLC_USED
-static inline uint16_t U16_AT( const void * _p )
+static inline uint16_t U16_AT (const void *p)
{
- const uint8_t * p = (const uint8_t *)_p;
- return ( ((uint16_t)p[0] << 8) | p[1] );
+ uint16_t x;
+
+ memcpy (&x, p, sizeof (x));
+ return ntoh16 (x);
}
+/** Reads 32 bits in network byte order */
VLC_USED
-static inline uint32_t U32_AT( const void * _p )
+static inline uint32_t U32_AT (const void *p)
{
- const uint8_t * p = (const uint8_t *)_p;
- return ( ((uint32_t)p[0] << 24) | ((uint32_t)p[1] << 16)
- | ((uint32_t)p[2] << 8) | p[3] );
+ uint32_t x;
+
+ memcpy (&x, p, sizeof (x));
+ return ntoh32 (x);
}
+/** Reads 64 bits in network byte order */
VLC_USED
-static inline uint64_t U64_AT( const void * _p )
+static inline uint64_t U64_AT (const void *p)
{
- const uint8_t * p = (const uint8_t *)_p;
- return ( ((uint64_t)p[0] << 56) | ((uint64_t)p[1] << 48)
- | ((uint64_t)p[2] << 40) | ((uint64_t)p[3] << 32)
- | ((uint64_t)p[4] << 24) | ((uint64_t)p[5] << 16)
- | ((uint64_t)p[6] << 8) | p[7] );
+ uint64_t x;
+
+ memcpy (&x, p, sizeof (x));
+ return ntoh64 (x);
}
+#define GetWBE(p) U16_AT(p)
+#define GetDWBE(p) U32_AT(p)
+#define GetQWBE(p) U64_AT(p)
+
+/** Reads 16 bits in little-endian order */
VLC_USED
-static inline uint16_t GetWLE( const void * _p )
+static inline uint16_t GetWLE (const void *p)
{
- const uint8_t * p = (const uint8_t *)_p;
- return ( ((uint16_t)p[1] << 8) | p[0] );
+ uint16_t x;
+
+ memcpy (&x, p, sizeof (x));
+#ifdef WORDS_BIGENDIAN
+ x = bswap16 (x);
+#endif
+ return x;
}
+/** Reads 32 bits in little-endian order */
VLC_USED
-static inline uint32_t GetDWLE( const void * _p )
+static inline uint32_t GetDWLE (const void *p)
{
- const uint8_t * p = (const uint8_t *)_p;
- return ( ((uint32_t)p[3] << 24) | ((uint32_t)p[2] << 16)
- | ((uint32_t)p[1] << 8) | p[0] );
+ uint32_t x;
+
+ memcpy (&x, p, sizeof (x));
+#ifdef WORDS_BIGENDIAN
+ x = bswap32 (x);
+#endif
+ return x;
}
+/** Reads 64 bits in little-endian order */
VLC_USED
-static inline uint64_t GetQWLE( const void * _p )
+static inline uint64_t GetQWLE (const void *p)
{
- const uint8_t * p = (const uint8_t *)_p;
- return ( ((uint64_t)p[7] << 56) | ((uint64_t)p[6] << 48)
- | ((uint64_t)p[5] << 40) | ((uint64_t)p[4] << 32)
- | ((uint64_t)p[3] << 24) | ((uint64_t)p[2] << 16)
- | ((uint64_t)p[1] << 8) | p[0] );
-}
+ uint64_t x;
-#define GetWBE( p ) U16_AT( p )
-#define GetDWBE( p ) U32_AT( p )
-#define GetQWBE( p ) U64_AT( p )
-
-/* Helper writer functions */
-#define SetWLE( p, v ) _SetWLE( (uint8_t*)(p), v)
-static inline void _SetWLE( uint8_t *p, uint16_t i_dw )
-{
- p[1] = ( i_dw >> 8 )&0xff;
- p[0] = ( i_dw )&0xff;
+ memcpy (&x, p, sizeof (x));
+#ifdef WORDS_BIGENDIAN
+ x = bswap64 (x);
+#endif
+ return x;
}
-#define SetDWLE( p, v ) _SetDWLE( (uint8_t*)(p), v)
-static inline void _SetDWLE( uint8_t *p, uint32_t i_dw )
+/** Writes 16 bits in network byte order */
+static inline void SetWLE (void *p, uint16_t w)
{
- p[3] = ( i_dw >> 24 )&0xff;
- p[2] = ( i_dw >> 16 )&0xff;
- p[1] = ( i_dw >> 8 )&0xff;
- p[0] = ( i_dw )&0xff;
+ w = hton16 (w);
+ memcpy (p, &w, sizeof (w));
}
-#define SetQWLE( p, v ) _SetQWLE( (uint8_t*)(p), v)
-static inline void _SetQWLE( uint8_t *p, uint64_t i_qw )
+
+/** Writes 32 bits in network byte order */
+static inline void SetDWLE (void *p, uint32_t dw)
{
- SetDWLE( p, i_qw&0xffffffff );
- SetDWLE( p+4, ( i_qw >> 32)&0xffffffff );
+ dw = hton32 (dw);
+ memcpy (p, &dw, sizeof (dw));
}
-#define SetWBE( p, v ) _SetWBE( (uint8_t*)(p), v)
-static inline void _SetWBE( uint8_t *p, uint16_t i_dw )
+
+/** Writes 64 bits in network byte order */
+static inline void SetQWLE (void *p, uint64_t qw)
{
- p[0] = ( i_dw >> 8 )&0xff;
- p[1] = ( i_dw )&0xff;
+ qw = hton64 (qw);
+ memcpy (p, &qw, sizeof (qw));
}
-#define SetDWBE( p, v ) _SetDWBE( (uint8_t*)(p), v)
-static inline void _SetDWBE( uint8_t *p, uint32_t i_dw )
+/** Writes 16 bits in little endian order */
+static inline void SetWBE (void *p, uint16_t w)
{
- p[0] = ( i_dw >> 24 )&0xff;
- p[1] = ( i_dw >> 16 )&0xff;
- p[2] = ( i_dw >> 8 )&0xff;
- p[3] = ( i_dw )&0xff;
+#ifdef WORDS_BIGENDIAN
+ w = bswap16 (w);
+#endif
+ memcpy (p, &w, sizeof (w));
}
-#define SetQWBE( p, v ) _SetQWBE( (uint8_t*)(p), v)
-static inline void _SetQWBE( uint8_t *p, uint64_t i_qw )
+
+/** Writes 32 bits in little endian order */
+static inline void SetDWBE (void *p, uint32_t dw)
{
- SetDWBE( p+4, i_qw&0xffffffff );
- SetDWBE( p, ( i_qw >> 32)&0xffffffff );
+#ifdef WORDS_BIGENDIAN
+ dw = bswap32 (dw);
+#endif
+ memcpy (p, &dw, sizeof (dw));
}
-#define hton16(i) htons(i)
-#define hton32(i) htonl(i)
-#define ntoh16(i) ntohs(i)
-#define ntoh32(i) ntohl(i)
-
-VLC_USED
-static inline uint64_t ntoh64 (uint64_t ll)
+/** Writes 64 bits in little endian order */
+static inline void SetQWBE (void *p, uint64_t qw)
{
- union { uint64_t qw; uint8_t b[16]; } v = { ll };
- return ((uint64_t)v.b[0] << 56)
- | ((uint64_t)v.b[1] << 48)
- | ((uint64_t)v.b[2] << 40)
- | ((uint64_t)v.b[3] << 32)
- | ((uint64_t)v.b[4] << 24)
- | ((uint64_t)v.b[5] << 16)
- | ((uint64_t)v.b[6] << 8)
- | ((uint64_t)v.b[7] << 0);
+#ifdef WORDS_BIGENDIAN
+ qw = bswap32 (qw);
+#endif
+ memcpy (p, &qw, sizeof (qw));
}
-#define hton64(i) ntoh64(i)
/* */
#define VLC_UNUSED(x) (void)(x)
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