MathGem:Endian Operations

From GPWiki

These functions deal with converting endianness. For more information on endianess, take a look at Wikipedia's article on Endianness.

Convert a WORD

This macro will flip the bytes within a WORD (2 Byte) value to convert between little endian and big endian format.

C/C++

You can also use htons() and ntohs() to convert between host and network byte order. On Linux these functions can be found in netinet/in.h and on Windows they are a part of Winsock2 and can be found in Winsock2.h.

#define FlipWord(w) ( (w)<<8 | (w)>>8 ) 

Python

You can also use htons() and ntohs() to convert between host and network byte order. These functions are found in the socket module.

def FlipWord(w):
    return ((w << 8) & 0x0FF00) | (w >> 8)

Convert a DWORD

This macro will flip the bytes within a DWORD (4 byte) value to convert between little endian and big endian format.

C/C++

You can also use htonl() and ntohl() to convert between host and network byte order. On Linux these functions can be found in netinet/in.h and on Windows they are a part of Winsock2 and can be found in Winsock2.h.

#define FlipDword(d) ((d)<<24 | (((d)<<8) & 0x00FF0000) | (((d)>>8) & 0x0000FF00) | (d)>>24) 

Python

You can also use htonl() and ntohl() to convert between host and network byte order. These functions are found in the socket module.

def FlipDword(d):
    return (((d)<<24) & 0xFF000000) | (((d)<<8) & 0x00FF0000) | (((d)>>8) & 0x0000FF00) | (d)>>24)