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/*
* swap.c
*
* Created on: 17.07.2011
* Author: holger
*/
#include "stdio.h"
#include "math.h"
// swap using char pointers
unsigned long long swap(double d)
{
unsigned long long a;
unsigned char *dst = (unsigned char *)&a;
unsigned char *src = (unsigned char *)&d;
dst[0] = src[7];
dst[1] = src[6];
dst[2] = src[5];
dst[3] = src[4];
dst[4] = src[3];
dst[5] = src[2];
dst[6] = src[1];
dst[7] = src[0];
return a;
}
// unswap using char pointers
double unswap(unsigned long long a)
{
double d;
unsigned char *src = (unsigned char *)&a;
unsigned char *dst = (unsigned char *)&d;
dst[0] = src[7];
dst[1] = src[6];
dst[2] = src[5];
dst[3] = src[4];
dst[4] = src[3];
dst[5] = src[2];
dst[6] = src[1];
dst[7] = src[0];
return d;
}
int main(int argc,char *argv[])
{
double a;
unsigned long long b;
double c;
for(a=0.0;a<100.0;a+=0.01) {
// swap to network byte order
b = swap(a);
// swap back
c = unswap(b);
// now a and C should be EXACTLY the same. but if not, print something
if (a == c) {
printf("*****\n%f\n%f\n%f\n%f\n",
a,b,c,fabs(a-c));
}
}
return 0;
}
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