OpenCores
URL https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk

Subversion Repositories openrisc_2011-10-31

[/] [openrisc/] [tags/] [gnu-src/] [newlib-1.18.0/] [newlib-1.18.0-or32-1.0rc1/] [newlib/] [libm/] [common/] [s_trunc.c] - Blame information for rev 345

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 207 jeremybenn 
/*
2 
 * ====================================================
3 
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 
 *
5 
 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 
 * Permission to use, copy, modify, and distribute this
7 
 * software is freely granted, provided that this notice
8 
 * is preserved.
9 
 * ====================================================
10 
 */
11 
/*
12 
FUNCTION
13 
<<trunc>>, <<truncf>>--round to integer, towards zero
14 
INDEX
15 
        trunc
16 
INDEX
17 
        truncf
18 
 
19 
ANSI_SYNOPSIS
20 
        #include <math.h>
21 
        double trunc(double <[x]>);
22 
        float truncf(float <[x]>);
23 
 
24 
DESCRIPTION
25 
        The <<trunc>> functions round their argument to the integer value, in
26 
        floating format, nearest to but no larger in magnitude than the
27 
        argument, regardless of the current rounding direction.  (While the
28 
        "inexact" floating-point exception behavior is unspecified by the C
29 
        standard, the <<trunc>> functions are written so that "inexact" is not
30 
        raised if the result does not equal the argument, which behavior is as
31 
        recommended by IEEE 754 for its related functions.)
32 
 
33 
RETURNS
34 
<[x]> truncated to an integral value.
35 
 
36 
PORTABILITY
37 
ANSI C, POSIX
38 
 
39 
*/
40 
 
41 
#include "fdlibm.h"
42 
 
43 
#ifndef _DOUBLE_IS_32BITS
44 
 
45 
#ifdef __STDC__
46 
        double trunc(double x)
47 
#else
48 
        double trunc(x)
49 
        double x;
50 
#endif
51 
{
52 
  int signbit;
53 
  /* Most significant word, least significant word. */
54 
  int msw;
55 
  unsigned int lsw;
56 
  int exponent_less_1023;
57 
 
58 
  EXTRACT_WORDS(msw, lsw, x);
59 
 
60 
  /* Extract sign bit. */
61 
  signbit = msw & 0x80000000;
62 
 
63 
  /* Extract exponent field. */
64 
  exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
65 
 
66 
  if (exponent_less_1023 < 20)
67 
    {
68 
      /* All significant digits are in msw. */
69 
      if (exponent_less_1023 < 0)
70 
        {
71 
          /* -1 < x < 1, so result is +0 or -0. */
72 
          INSERT_WORDS(x, signbit, 0);
73 
        }
74 
      else
75 
        {
76 
          /* All relevant fraction bits are in msw, so lsw of the result is 0. */
77 
          INSERT_WORDS(x, signbit | (msw & ~(0x000fffff >> exponent_less_1023)), 0);
78 
        }
79 
    }
80 
  else if (exponent_less_1023 > 51)
81 
    {
82 
      if (exponent_less_1023 == 1024)
83 
        {
84 
          /* x is infinite, or not a number, so trigger an exception. */
85 
          return x + x;
86 
        }
87 
      /* All bits in the fraction fields of the msw and lsw are needed in the result. */
88 
    }
89 
  else
90 
    {
91 
      /* All fraction bits in msw are relevant.  Truncate irrelevant
92 
         bits from lsw. */
93 
      INSERT_WORDS(x, msw, lsw & ~(0xffffffffu >> (exponent_less_1023 - 20)));
94 
    }
95 
  return x;
96 
}
97 
 
98 
#endif /* _DOUBLE_IS_32BITS */

powered by: WebSVN 2.1.0

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