1#include "libm.h" 2 3double modf(double x, double* iptr) { 4 union { 5 double f; 6 uint64_t i; 7 } u = {x}; 8 uint64_t mask; 9 int e = (int)(u.i >> 52 & 0x7ff) - 0x3ff; 10 11 /* no fractional part */ 12 if (e >= 52) { 13 *iptr = x; 14 if (e == 0x400 && u.i << 12 != 0) /* nan */ 15 return x; 16 u.i &= 1ULL << 63; 17 return u.f; 18 } 19 20 /* no integral part*/ 21 if (e < 0) { 22 u.i &= 1ULL << 63; 23 *iptr = u.f; 24 return x; 25 } 26 27 mask = -1ULL >> 12 >> e; 28 if ((u.i & mask) == 0) { 29 *iptr = x; 30 u.i &= 1ULL << 63; 31 return u.f; 32 } 33 u.i &= ~mask; 34 *iptr = u.f; 35 return x - u.f; 36} 37