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Objective C - 与Android交互时高低位转换:
在与Android交互过程中,因为Android是从低位往高位读,iOS是从高位往低位读,所以交互数据需要进行转换。
/* * convert big endian to little endian in C */ uint16_t swap_uint16( uint16_t val ); int16_t swap_int16( int16_t val ); uint32_t swap_uint32( uint32_t val ); int32_t swap_int32( int32_t val ); int64_t swap_int64( int64_t val ); uint64_t swap_uint64( uint64_t val ); //////////////////////////////////////////////////////////////////////////////////////////////////// //! Byte swap unsigned short uint16_t swap_uint16( uint16_t val ) { return (val << 8) | (val >> 8 ); } //! Byte swap short int16_t swap_int16( int16_t val ) { return (val << 8) | ((val >> 8) & 0xFF); } //! Byte swap unsigned int uint32_t swap_uint32( uint32_t val ) { val = ((val << 8) & 0xFF00FF00 ) | ((val >> 8) & 0xFF00FF ); return (val << 16) | (val >> 16); } //! Byte swap int int32_t swap_int32( int32_t val ) { val = ((val << 8) & 0xFF00FF00) | ((val >> 8) & 0xFF00FF ); return (val << 16) | ((val >> 16) & 0xFFFF); } int64_t swap_int64( int64_t val ) { val = ((val << 8) & 0xFF00FF00FF00FF00ULL ) | ((val >> 8) & 0x00FF00FF00FF00FFULL ); val = ((val << 16) & 0xFFFF0000FFFF0000ULL ) | ((val >> 16) & 0x0000FFFF0000FFFFULL ); val = (val << 32) | ((val >> 32) & 0xFFFFFFFFULL); return val; } uint64_t swap_uint64( uint64_t val ) { val = ((val << 8) & 0xFF00FF00FF00FF00ULL ) | ((val >> 8) & 0x00FF00FF00FF00FFULL ); val = ((val << 16) & 0xFFFF0000FFFF0000ULL ) | ((val >> 16) & 0x0000FFFF0000FFFFULL ); val = (val << 32) | (val >> 32); return val; }
调用:
UInt64 recordTime = [[NSDate date] timeIntervalSince1970]*1000; UInt64 value = http://www.mamicode.com/swap_uint64(recordTime);
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