1#include "libm.h" 2 3double trunc(double x) { 4 union { 5 double f; 6 uint64_t i; 7 } u = {x}; 8 int e = (int)(u.i >> 52 & 0x7ff) - 0x3ff + 12; 9 uint64_t m; 10 11 if (e >= 52 + 12) 12 return x; 13 if (e < 12) 14 e = 1; 15 m = -1ULL >> e; 16 if ((u.i & m) == 0) 17 return x; 18 FORCE_EVAL(x + 0x1p120f); 19 u.i &= ~m; 20 return u.f; 21} 22