convert big endian to little endian in C [without using provided func] [closed]

Answer 1

If you are running on a x86 or x86_64 processor, the big endian is native. so

for 16 bit values

unsigned short wBigE = value;
unsigned short wLittleE = ((wBigE & 0xFF) << 8) | (wBigE >> 8);

for 32 bit values

unsigned int   iBigE = value;
unsigned int   iLittleE = ((iBigE & 0xFF) << 24)
                        | ((iBigE & 0xFF00) << 8)
                        | ((iBigE >> 8) & 0xFF00)
                        | (iBigE >> 24);

This isn't the most efficient solution unless the compiler recognises that this is byte level manipulation and generates byte swapping code. But it doesn't depend on any memory layout tricks and can be turned into a macro pretty easily.