nsz Git - musl/blob - src/math/scalbn.c

   1 #include "libm.h"
   2
   3 double scalbn(double x, int n)
   4 {
   5         double scale;
   6
   7         if (n > 1023) {
   8                 x *= 0x1p1023;
   9                 n -= 1023;
  10                 if (n > 1023) {
  11                         x *= 0x1p1023;
  12                         n -= 1023;
  13                         if (n > 1023) {
  14                                 STRICT_ASSIGN(double, x, x * 0x1p1023);
  15                                 return x;
  16                         }
  17                 }
  18         } else if (n < -1022) {
  19                 x *= 0x1p-1022;
  20                 n += 1022;
  21                 if (n < -1022) {
  22                         x *= 0x1p-1022;
  23                         n += 1022;
  24                         if (n < -1022) {
  25                                 STRICT_ASSIGN(double, x, x * 0x1p-1022);
  26                                 return x;
  27                         }
  28                 }
  29         }
  30         INSERT_WORDS(scale, (uint32_t)(0x3ff+n)<<20, 0);
  31         STRICT_ASSIGN(double, x, x * scale);
  32         return x;
  33 }