Using macros to simulate the implementation of HTONL, Ntohl, htons, Ntohs

typedef unsigned short int uint16;
typedef unsigned long int uint32;

Short-integer-size-end interchange
#define BIGLITTLESWAP16 (A) (((UInt16) (a) & 0xff00) >> 8) |/
(((UInt16) (A) & 0X00FF) << 8))

Long Integer size End interchange
#define BIGLITTLESWAP32 (A) (((UInt32) (a) & 0xff000000) >> 24) |/
(((UInt32) (A) & 0x00ff0000) >> 8) | /
(((UInt32) (A) & 0x0000ff00) << 8) | /
(((UInt32) (A) & 0x000000ff) << 24))

Native big end returns 1, small side returns 0
int Checkcpuendian ()
{
union{
unsigned long int i;
unsigned char s[4];
}c = {0x12345678};

return (0x12 = = C.s[0]);
}

Analog htonl function, native byte sequence to network byte order
#define HTONL (A) (Checkcpuendian ()? (a): BigLittleSwap32 (a))

Analog Ntohl function, network byte sequence to native byte order
#define NTOHL (a) htonl (a)

Analog htons function, native byte sequence to network byte order
#define HTONS (A) (Checkcpuendian ()? (a): BigLittleSwap16 (a))

Analog Ntohs function, network byte sequence to native byte order
#define NTOHS (a) HtoNs (a)