github.com/afumu/libc@v0.0.6/musl/src/math/exp10f.c (about)

     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);