github.com/afumu/libc@v0.0.6/musl/src/math/exp10l.c (about)

     1  #define _GNU_SOURCE
     2  #include <float.h>
     3  #include <math.h>
     4  #include "libm.h"
     5  
     6  #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
     7  long double exp10l(long double x)
     8  {
     9  	return exp10(x);
    10  }
    11  #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
    12  long double exp10l(long double x)
    13  {
    14  	static const long double p10[] = {
    15  		1e-15L, 1e-14L, 1e-13L, 1e-12L, 1e-11L, 1e-10L,
    16  		1e-9L, 1e-8L, 1e-7L, 1e-6L, 1e-5L, 1e-4L, 1e-3L, 1e-2L, 1e-1L,
    17  		1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
    18  		1e10, 1e11, 1e12, 1e13, 1e14, 1e15
    19  	};
    20  	long double n, y = modfl(x, &n);
    21  	union ldshape u = {n};
    22  	/* fabsl(n) < 16 without raising invalid on nan */
    23  	if ((u.i.se & 0x7fff) < 0x3fff+4) {
    24  		if (!y) return p10[(int)n+15];
    25  		y = exp2l(3.32192809488736234787031942948939L * y);
    26  		return y * p10[(int)n+15];
    27  	}
    28  	return powl(10.0, x);
    29  }
    30  #endif
    31  
    32  weak_alias(exp10l, pow10l);