Define bit_SSE2 and index_SSE2.
[glibc.git] / sysdeps / ieee754 / flt-32 / s_expm1f.c
blob3f4536b906fa85b89c87bc19027f8f9aff904119
1 /* s_expm1f.c -- float version of s_expm1.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
5 /*
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
12 * is preserved.
13 * ====================================================
16 #if defined(LIBM_SCCS) && !defined(lint)
17 static char rcsid[] = "$NetBSD: s_expm1f.c,v 1.5 1995/05/10 20:47:11 jtc Exp $";
18 #endif
20 #include <errno.h>
21 #include "math.h"
22 #include "math_private.h"
24 static const volatile float huge = 1.0e+30;
25 static const volatile float tiny = 1.0e-30;
27 #ifdef __STDC__
28 static const float
29 #else
30 static float
31 #endif
32 one = 1.0,
33 o_threshold = 8.8721679688e+01,/* 0x42b17180 */
34 ln2_hi = 6.9313812256e-01,/* 0x3f317180 */
35 ln2_lo = 9.0580006145e-06,/* 0x3717f7d1 */
36 invln2 = 1.4426950216e+00,/* 0x3fb8aa3b */
37 /* scaled coefficients related to expm1 */
38 Q1 = -3.3333335072e-02, /* 0xbd088889 */
39 Q2 = 1.5873016091e-03, /* 0x3ad00d01 */
40 Q3 = -7.9365076090e-05, /* 0xb8a670cd */
41 Q4 = 4.0082177293e-06, /* 0x36867e54 */
42 Q5 = -2.0109921195e-07; /* 0xb457edbb */
44 #ifdef __STDC__
45 float __expm1f(float x)
46 #else
47 float __expm1f(x)
48 float x;
49 #endif
51 float y,hi,lo,c,t,e,hxs,hfx,r1;
52 int32_t k,xsb;
53 u_int32_t hx;
55 GET_FLOAT_WORD(hx,x);
56 xsb = hx&0x80000000; /* sign bit of x */
57 if(xsb==0) y=x; else y= -x; /* y = |x| */
58 hx &= 0x7fffffff; /* high word of |x| */
60 /* filter out huge and non-finite argument */
61 if(hx >= 0x4195b844) { /* if |x|>=27*ln2 */
62 if(hx >= 0x42b17218) { /* if |x|>=88.721... */
63 if(hx>0x7f800000)
64 return x+x; /* NaN */
65 if(hx==0x7f800000)
66 return (xsb==0)? x:-1.0;/* exp(+-inf)={inf,-1} */
67 if(x > o_threshold) {
68 __set_errno (ERANGE);
69 return huge*huge; /* overflow */
72 if(xsb!=0) { /* x < -27*ln2, return -1.0 with inexact */
73 if(x+tiny<(float)0.0) /* raise inexact */
74 return tiny-one; /* return -1 */
78 /* argument reduction */
79 if(hx > 0x3eb17218) { /* if |x| > 0.5 ln2 */
80 if(hx < 0x3F851592) { /* and |x| < 1.5 ln2 */
81 if(xsb==0)
82 {hi = x - ln2_hi; lo = ln2_lo; k = 1;}
83 else
84 {hi = x + ln2_hi; lo = -ln2_lo; k = -1;}
85 } else {
86 k = invln2*x+((xsb==0)?(float)0.5:(float)-0.5);
87 t = k;
88 hi = x - t*ln2_hi; /* t*ln2_hi is exact here */
89 lo = t*ln2_lo;
91 x = hi - lo;
92 c = (hi-x)-lo;
94 else if(hx < 0x33000000) { /* when |x|<2**-25, return x */
95 t = huge+x; /* return x with inexact flags when x!=0 */
96 return x - (t-(huge+x));
98 else k = 0;
100 /* x is now in primary range */
101 hfx = (float)0.5*x;
102 hxs = x*hfx;
103 r1 = one+hxs*(Q1+hxs*(Q2+hxs*(Q3+hxs*(Q4+hxs*Q5))));
104 t = (float)3.0-r1*hfx;
105 e = hxs*((r1-t)/((float)6.0 - x*t));
106 if(k==0) return x - (x*e-hxs); /* c is 0 */
107 else {
108 e = (x*(e-c)-c);
109 e -= hxs;
110 if(k== -1) return (float)0.5*(x-e)-(float)0.5;
111 if(k==1) {
112 if(x < (float)-0.25) return -(float)2.0*(e-(x+(float)0.5));
113 else return one+(float)2.0*(x-e);
115 if (k <= -2 || k>56) { /* suffice to return exp(x)-1 */
116 int32_t i;
117 y = one-(e-x);
118 GET_FLOAT_WORD(i,y);
119 SET_FLOAT_WORD(y,i+(k<<23)); /* add k to y's exponent */
120 return y-one;
122 t = one;
123 if(k<23) {
124 int32_t i;
125 SET_FLOAT_WORD(t,0x3f800000 - (0x1000000>>k)); /* t=1-2^-k */
126 y = t-(e-x);
127 GET_FLOAT_WORD(i,y);
128 SET_FLOAT_WORD(y,i+(k<<23)); /* add k to y's exponent */
129 } else {
130 int32_t i;
131 SET_FLOAT_WORD(t,((0x7f-k)<<23)); /* 2^-k */
132 y = x-(e+t);
133 y += one;
134 GET_FLOAT_WORD(i,y);
135 SET_FLOAT_WORD(y,i+(k<<23)); /* add k to y's exponent */
138 return y;
140 weak_alias (__expm1f, expm1f)