OpenCores
URL https://opencores.org/ocsvn/openrisc_me/openrisc_me/trunk

Subversion Repositories openrisc_me

[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libm/] [common/] [sf_expm1.c] - Blame information for rev 365

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 148 jeremybenn 
/* sf_expm1.c -- float version of s_expm1.c.
2 
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 
 */
4 
 
5 
/*
6 
 * ====================================================
7 
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 
 *
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 
 * ====================================================
14 
 */
15 
 
16 
#include "fdlibm.h"
17 
 
18 
#ifdef __v810__
19 
#define const
20 
#endif
21 
 
22 
#ifdef __STDC__
23 
static const float
24 
#else
25 
static float
26 
#endif
27 
one             = 1.0,
28 
huge            = 1.0e+30,
29 
tiny            = 1.0e-30,
30 
ln2_hi          = 6.9313812256e-01,/* 0x3f317180 */
31 
ln2_lo          = 9.0580006145e-06,/* 0x3717f7d1 */
32 
invln2          = 1.4426950216e+00,/* 0x3fb8aa3b */
33 
        /* scaled coefficients related to expm1 */
34 
Q1  =  -3.3333335072e-02, /* 0xbd088889 */
35 
Q2  =   1.5873016091e-03, /* 0x3ad00d01 */
36 
Q3  =  -7.9365076090e-05, /* 0xb8a670cd */
37 
Q4  =   4.0082177293e-06, /* 0x36867e54 */
38 
Q5  =  -2.0109921195e-07; /* 0xb457edbb */
39 
 
40 
#ifdef __STDC__
41 
        float expm1f(float x)
42 
#else
43 
        float expm1f(x)
44 
        float x;
45 
#endif
46 
{
47 
        float y,hi,lo,c,t,e,hxs,hfx,r1;
48 
        __int32_t k,xsb;
49 
        __uint32_t hx;
50 
 
51 
        GET_FLOAT_WORD(hx,x);
52 
        xsb = hx&0x80000000;            /* sign bit of x */
53 
        if(xsb==0) y=x; else y= -x;      /* y = |x| */
54 
        hx &= 0x7fffffff;               /* high word of |x| */
55 
 
56 
    /* filter out huge and non-finite argument */
57 
        if(hx >= 0x4195b844) {                  /* if |x|>=27*ln2 */
58 
            if(FLT_UWORD_IS_NAN(hx))
59 
                return x+x;
60 
            if(FLT_UWORD_IS_INFINITE(hx))
61 
                return (xsb==0)? x:-1.0;/* exp(+-inf)={inf,-1} */
62 
            if(xsb == 0 && hx > FLT_UWORD_LOG_MAX) /* if x>=o_threshold */
63 
                return huge*huge; /* overflow */
64 
            if(xsb!=0) { /* x < -27*ln2, return -1.0 with inexact */
65 
                if(x+tiny<(float)0.0)   /* raise inexact */
66 
                return tiny-one;        /* return -1 */
67 
            }
68 
        }
69 
 
70 
    /* argument reduction */
71 
        if(hx > 0x3eb17218) {           /* if  |x| > 0.5 ln2 */
72 
            if(hx < 0x3F851592) {       /* and |x| < 1.5 ln2 */
73 
                if(xsb==0)
74 
                    {hi = x - ln2_hi; lo =  ln2_lo;  k =  1;}
75 
                else
76 
                    {hi = x + ln2_hi; lo = -ln2_lo;  k = -1;}
77 
            } else {
78 
                k  = invln2*x+((xsb==0)?(float)0.5:(float)-0.5);
79 
                t  = k;
80 
                hi = x - t*ln2_hi;      /* t*ln2_hi is exact here */
81 
                lo = t*ln2_lo;
82 
            }
83 
            x  = hi - lo;
84 
            c  = (hi-x)-lo;
85 
        }
86 
        else if(hx < 0x33000000) {      /* when |x|<2**-25, return x */
87 
            t = huge+x; /* return x with inexact flags when x!=0 */
88 
            return x - (t-(huge+x));
89 
        }
90 
        else k = 0;
91 
 
92 
    /* x is now in primary range */
93 
        hfx = (float)0.5*x;
94 
        hxs = x*hfx;
95 
        r1 = one+hxs*(Q1+hxs*(Q2+hxs*(Q3+hxs*(Q4+hxs*Q5))));
96 
        t  = (float)3.0-r1*hfx;
97 
        e  = hxs*((r1-t)/((float)6.0 - x*t));
98 
        if(k==0) return x - (x*e-hxs);           /* c is 0 */
99 
        else {
100 
            e  = (x*(e-c)-c);
101 
            e -= hxs;
102 
            if(k== -1) return (float)0.5*(x-e)-(float)0.5;
103 
           if(k==1) {
104 
                if(x < (float)-0.25) return -(float)2.0*(e-(x+(float)0.5));
105 
                else          return  one+(float)2.0*(x-e);
106 
           }
107 
            if (k <= -2 || k>56) {   /* suffice to return exp(x)-1 */
108 
                __int32_t i;
109 
                y = one-(e-x);
110 
                GET_FLOAT_WORD(i,y);
111 
                SET_FLOAT_WORD(y,i+(k<<23));    /* add k to y's exponent */
112 
                return y-one;
113 
            }
114 
            t = one;
115 
            if(k<23) {
116 
                __int32_t i;
117 
                SET_FLOAT_WORD(t,0x3f800000 - (0x1000000>>k)); /* t=1-2^-k */
118 
                y = t-(e-x);
119 
                GET_FLOAT_WORD(i,y);
120 
                SET_FLOAT_WORD(y,i+(k<<23));    /* add k to y's exponent */
121 
           } else {
122 
                __int32_t i;
123 
                SET_FLOAT_WORD(t,((0x7f-k)<<23));       /* 2^-k */
124 
                y = x-(e+t);
125 
                y += one;
126 
                GET_FLOAT_WORD(i,y);
127 
                SET_FLOAT_WORD(y,i+(k<<23));    /* add k to y's exponent */
128 
            }
129 
        }
130 
        return y;
131 
}
132 
 
133 
#ifdef _DOUBLE_IS_32BITS
134 
 
135 
#ifdef __STDC__
136 
        double expm1(double x)
137 
#else
138 
        double expm1(x)
139 
        double x;
140 
#endif
141 
{
142 
        return (double) expm1f((float) x);
143 
}
144 
 
145 
#endif /* defined(_DOUBLE_IS_32BITS) */

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.