1 /* e_log10f.c -- float version of e_log10.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
13 * ====================================================
17 #include <math_private.h>
18 #include <fix-int-fp-convert-zero.h>
21 two25
= 3.3554432000e+07, /* 0x4c000000 */
22 ivln10
= 4.3429449201e-01, /* 0x3ede5bd9 */
23 log10_2hi
= 3.0102920532e-01, /* 0x3e9a2080 */
24 log10_2lo
= 7.9034151668e-07; /* 0x355427db */
27 __ieee754_log10f(float x
)
35 if (hx
< 0x00800000) { /* x < 2**-126 */
36 if (__builtin_expect((hx
&0x7fffffff)==0, 0))
37 return -two25
/__fabsf (x
); /* log(+-0)=-inf */
38 if (__builtin_expect(hx
<0, 0))
39 return (x
-x
)/(x
-x
); /* log(-#) = NaN */
40 k
-= 25; x
*= two25
; /* subnormal number, scale up x */
43 if (__builtin_expect(hx
>= 0x7f800000, 0)) return x
+x
;
45 i
= ((u_int32_t
)k
&0x80000000)>>31;
46 hx
= (hx
&0x007fffff)|((0x7f-i
)<<23);
48 if (FIX_INT_FP_CONVERT_ZERO
&& y
== 0.0f
)
51 z
= y
*log10_2lo
+ ivln10
*__ieee754_logf(x
);
54 strong_alias (__ieee754_log10f
, __log10f_finite
)