POK
e_sinhf.c
1 /*
2  * POK header
3  *
4  * The following file is a part of the POK project. Any modification should
5  * made according to the POK licence. You CANNOT use this file or a part of
6  * this file is this part of a file for your own project
7  *
8  * For more information on the POK licence, please see our LICENCE FILE
9  *
10  * Please follow the coding guidelines described in doc/CODING_GUIDELINES
11  *
12  * Copyright (c) 2007-2009 POK team
13  *
14  * Created by julien on Fri Jan 30 14:41:34 2009
15  */
16 
17 /* e_sinhf.c -- float version of e_sinh.c.
18  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
19  */
20 
21 /*
22  * ====================================================
23  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
24  *
25  * Developed at SunPro, a Sun Microsystems, Inc. business.
26  * Permission to use, copy, modify, and distribute this
27  * software is freely granted, provided that this notice
28  * is preserved.
29  * ====================================================
30  */
31 
32 #ifdef POK_NEEDS_LIBMATH
33 
34 #include <libm.h>
35 #include "math_private.h"
36 
37 static const float one = 1.0, shuge = 1.0e37;
38 
39 float
40 __ieee754_sinhf(float x)
41 {
42  float t,w,h;
43  int32_t ix,jx;
44 
45  GET_FLOAT_WORD(jx,x);
46  ix = jx&0x7fffffff;
47 
48  /* x is INF or NaN */
49  if(ix>=0x7f800000) return x+x;
50 
51  h = 0.5;
52  if (jx<0) h = -h;
53  /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
54  if (ix < 0x41b00000) { /* |x|<22 */
55  if (ix<0x31800000) /* |x|<2**-28 */
56  if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
57  t = expm1f(fabsf(x));
58  if(ix<0x3f800000) return h*((float)2.0*t-t*t/(t+one));
59  return h*(t+t/(t+one));
60  }
61 
62  /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
63  if (ix < 0x42b17180) return h*__ieee754_expf(fabsf(x));
64 
65  /* |x| in [log(maxdouble), overflowthresold] */
66  if (ix<=0x42b2d4fc) {
67  w = __ieee754_expf((float)0.5*fabsf(x));
68  t = h*w;
69  return t*w;
70  }
71 
72  /* |x| > overflowthresold, sinh(x) overflow */
73  return x*shuge;
74 }
75 #endif
76