src/math/truncl.c

   1 #include "libm.h"
   2
   3 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
   4 long double truncl(long double x)
   5 {
   6         return trunc(x);
   7 }
   8 #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
   9
  10 static const long double toint = 1/LDBL_EPSILON;
  11
  12 long double truncl(long double x)
  13 {
  14         union ldshape u = {x};
  15         int e = u.i.se & 0x7fff;
  16         int s = u.i.se >> 15;
  17         long double y;
  18
  19         if (e >= 0x3fff+LDBL_MANT_DIG-1)
  20                 return x;
  21         if (e <= 0x3fff-1) {
  22                 FORCE_EVAL(x + 0x1p120f);
  23                 return x*0;
  24         }
  25         /* y = int(|x|) - |x|, where int(|x|) is an integer neighbor of |x| */
  26         if (s)
  27                 x = -x;
  28         y = x + toint - toint - x;
  29         if (y > 0)
  30                 y -= 1;
  31         x += y;
  32         return s ? -x : x;
  33 }
  34 #endif