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byteorder.h
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#ifndef ALGO_BYTEORDER_H__
#define ALGO_BYTEORDER_H__
#include <stdint.h>
#include <stdbool.h>
/**
* test endianness of current machine
* mem: 0D 0C 0B 0A //big endian
* mem: 0A 0B 0C 0D //little endian
* V=0x0D0C0B0A
*/
static inline bool
is_big_endian()
{
int v=0x0D0C0B0A;
char c = *(char*)&v;
if (c == 0x0A) return false;
return true;
}
/**
* uint16_t byte swap mask
*/
#define BYTE_MASK_A_ 0xff00
#define BYTE_MASK__B 0x00ff
/**
* byte swap 2-byte
*/
static inline uint16_t
byte_swap2(uint16_t original)
{
uint16_t swapped;
swapped = (( (original) & BYTE_MASK_A_) >> 8)
|
(( (original) & BYTE_MASK__B) <<8);
return swapped;
}
/**
* uint32_t byte swap mask
*/
#define BYTE_MASK_A_C_ 0xff00ff00
#define BYTE_MASK__B_D 0x00ff00ff
#define BYTE_MASK_AB__ 0xffff0000
#define BYTE_MASK___CD 0x0000ffff
/**
* byte swap 4-byte
*/
static inline uint32_t
byte_swap4(uint32_t original)
{
uint32_t swapped;
// ABCD => BADC
swapped = (( (original) & BYTE_MASK_A_C_ ) >> 8 )
|
(( (original) & BYTE_MASK__B_D ) << 8 );
// BADC => DCBA
swapped = (( swapped & BYTE_MASK_AB__ ) >> 16 )
|
(( swapped & BYTE_MASK___CD ) << 16 );
return swapped;
}
/*
* uint64_t byte swap mask
*/
#define BYTE_MASK_A_C_E_G_ 0xff00ff00ff00ff00ULL
#define BYTE_MASK__B_D_F_H 0x00ff00ff00ff00ffULL
#define BYTE_MASK_AB__EF__ 0xffff0000ffff0000ULL
#define BYTE_MASK___CD__GH 0x0000ffff0000ffffULL
#define BYTE_MASK_ABCD____ 0xffffffff00000000ULL
#define BYTE_MASK_____EFGH 0x00000000ffffffffULL
/**
* byte swap 8-byte
*/
static inline uint64_t
byte_swap8( uint64_t original )
{
uint64_t swapped;
// ABCDEFGH => BADCFEHG
swapped = (( (original) & BYTE_MASK_A_C_E_G_ ) >> 8 )
|
(( (original) & BYTE_MASK__B_D_F_H ) << 8 );
// BADCFEHG => DCBAHGFE
swapped = (( swapped & BYTE_MASK_AB__EF__ ) >> 16 )
|
(( swapped & BYTE_MASK___CD__GH ) << 16 );
// DCBAHGFE => HGFEDCBA
swapped = (( swapped & BYTE_MASK_ABCD____ ) >> 32 )
|
(( swapped & BYTE_MASK_____EFGH ) << 32 );
return swapped;
}
#endif //