From: Rémi Denis-Courmont Date: Wed, 17 Aug 2011 16:01:17 +0000 (+0300) Subject: Improve byte order inline functions X-Git-Tag: 1.2.0-pre1~1191 X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=9ff7bdc46882335bd4ead9f9b5d252b6cb3863f7;p=vlc 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. --- diff --git a/include/vlc_common.h b/include/vlc_common.h index 337fd8a0b7..9e49c35fb0 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)