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#include <math.h>
#include <errno.h>
/* modf suitable for IEEE double-precision */
#define MASK 0x7ffL
#define SIGN 0x80000000
#define SHIFT 20
#define BIAS 1022L
typedef union
{
double d;
struct
{
long ms;
long ls;
} i;
} Cheat;
double
modf(double d, double *ip)
{
Cheat x;
int e;
if(-1 < d && d < 1) {
*ip = 0;
return d;
}
x.d = d;
x.i.ms &= ~SIGN;
e = (x.i.ms >> SHIFT) & MASK;
if(e == MASK || e == 0){
errno = EDOM;
*ip = (d > 0)? HUGE_VAL : -HUGE_VAL;
return 0;
}
e -= BIAS;
if(e <= SHIFT+1) {
x.i.ms &= ~(0x1fffffL >> e);
x.i.ls = 0;
} else
if(e <= SHIFT+33)
x.i.ls &= ~(0x7fffffffL >> (e-SHIFT-2));
if(d > 0){
*ip = x.d;
return d - x.d;
}else{
*ip = -x.d;
return d + x.d;
}
}
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