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

Answer 1

Edit: These are library functions. Following them is the manual way to do it.

I am absolutely stunned by the number of people unaware of __byteswap_ushort, __byteswap_ulong, and __byteswap_uint64. Sure they are Visual C++ specific, but they compile down to some delicious code on x86/IA-64 architectures. :)

Here's an explicit usage of the bswap instruction, pulled from this page. Note that the intrinsic form above will always be faster than this, I only added it to give an answer without a library routine.

uint32 cq_ntohl(uint32 a) {
    __asm{
        mov eax, a;
        bswap eax; 
    }
}