POK
nextafterf.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 /* s_nextafterf.c -- float version of s_nextafter.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 float
38 nextafterf(float x, float y)
39 {
40  int32_t hx,hy,ix,iy;
41 
42  GET_FLOAT_WORD(hx,x);
43  GET_FLOAT_WORD(hy,y);
44  ix = hx&0x7fffffff; /* |x| */
45  iy = hy&0x7fffffff; /* |y| */
46 
47  if((ix>0x7f800000) || /* x is nan */
48  (iy>0x7f800000)) /* y is nan */
49  return x+y;
50  if(x==y) return x; /* x=y, return x */
51  if(ix==0) { /* x == 0 */
52  SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
53  y = x*x;
54  if(y==x) return y; else return x; /* raise underflow flag */
55  }
56  if(hx>=0) { /* x > 0 */
57  if(hx>hy) { /* x > y, x -= ulp */
58  hx -= 1;
59  } else { /* x < y, x += ulp */
60  hx += 1;
61  }
62  } else { /* x < 0 */
63  if(hy>=0||hx>hy){ /* x < y, x -= ulp */
64  hx -= 1;
65  } else { /* x > y, x += ulp */
66  hx += 1;
67  }
68  }
69  hy = hx&0x7f800000;
70  if(hy>=0x7f800000) return x+x; /* overflow */
71  if(hy<0x00800000) { /* underflow */
72  y = x*x;
73  if(y!=x) { /* raise underflow flag */
74  SET_FLOAT_WORD(y,hx);
75  return y;
76  }
77  }
78  SET_FLOAT_WORD(x,hx);
79  return x;
80 }
81 
82 #endif