exp10f.c raw

   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);
  23