src/math/exp10f.c

   1 #define _GNU_SOURCE
   2 #include <math.h>
   3 #include <stdint.h>
   4
   5 float exp10f(float x)
   6 {
   7         static const float p10[] = {
   8                 1e-7f, 1e-6f, 1e-5f, 1e-4f, 1e-3f, 1e-2f, 1e-1f,
   9                 1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7
  10         };
  11         float n, y = modff(x, &n);
  12         union {float f; uint32_t i;} u = {n};
  13         /* fabsf(n) < 8 without raising invalid on nan */
  14         if ((u.i>>23 & 0xff) < 0x7f+3) {
  15                 if (!y) return p10[(int)n+7];
  16                 y = exp2f(3.32192809488736234787031942948939f * y);
  17                 return y * p10[(int)n+7];
  18         }
  19         return exp2(3.32192809488736234787031942948939 * x);
  20 }
  21
  22 weak_alias(exp10f, pow10f);