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 = swap_uint64(recordTime);