#include <stdio.h>
#include <stdlib.h>

int byteswap( void *swappee, int Nbytes )
{
    char temp, *ptr = swappee ;

    if( Nbytes == 2 ){
        temp   = ptr[0] ;
        ptr[0] = ptr[1] ;
        ptr[1] = temp ;
        return 0 ;
    }

    if( Nbytes == 4 ){
        temp   = ptr[0] ;
        ptr[0] = ptr[3] ;
        ptr[3] = temp ;

        temp   = ptr[1] ;
        ptr[1] = ptr[2] ;
        ptr[2] = temp ;
        return 0 ;
    }

     if( Nbytes == 8 ){
        temp   = ptr[0] ;
        ptr[0] = ptr[7] ;
        ptr[7] = temp ;

        temp   = ptr[1] ;
        ptr[1] = ptr[6] ;
        ptr[6] = temp ;

        temp   = ptr[2] ;
        ptr[2] = ptr[5] ;
        ptr[5] = temp ;

        temp   = ptr[3] ;
        ptr[3] = ptr[4] ;
        ptr[4] = temp ;
        return 0 ;
    }

    return -1 ;
}

int main()
{
    float f;
    unsigned char cbuf[4];
    unsigned char *p;

    cbuf[0] = 0xff;
    cbuf[1] = 0xae;
    cbuf[2] = 0x47;
    cbuf[3] = 0xc5;
    printf("%x %x %x %x --> ", (unsigned char)cbuf[0], (unsigned char)cbuf[1],
	    (unsigned char)cbuf[2], (unsigned char)cbuf[3]);
    f = *((float *)cbuf);
    byteswap((void *)(&f), 4);

    p = (unsigned char *)&f;
    printf("%x %x %x %x\n", *p, *(p + 1), *(p + 2), *(p + 3));

    return 0;
}