1
2 /* @(#)sf_lrint.c 5.1 93/09/24 */
3 /*
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 *
7 * Developed at SunPro, a Sun Microsystems, Inc. business.
8 * Permission to use, copy, modify, and distribute this
9 * software is freely granted, provided that this notice
10 * is preserved.
11 * ====================================================
12 */
13
14 /*
15 * lrintf(x)
16 * Return x rounded to integral value according to the prevailing
17 * rounding mode.
18 * Method:
19 * Using floating addition.
20 * Exception:
21 * Inexact flag raised if x not equal to lrintf(x).
22 */
23
24 #include "fdlibm.h"
25 #include <limits.h>
26
27 static const float
28 /* Adding a float, x, to 2^23 will cause the result to be rounded based on
29 the fractional part of x, according to the implementation's current rounding
30 mode. 2^23 is the smallest float that can be represented using all 23 significant
31 digits. */
32 TWO23[2]={
33 8.3886080000e+06, /* 0x4b000000 */
34 -8.3886080000e+06, /* 0xcb000000 */
35 };
36
lrintf(float x)37 long int lrintf(float x)
38 {
39 __int32_t j0,sx;
40 __uint32_t i0;
41 float t;
42 volatile float w;
43 long int result;
44
45 GET_FLOAT_WORD(i0,x);
46
47 /* Extract sign bit. */
48 sx = (i0 >> 31);
49
50 /* Extract exponent field. */
51 j0 = ((i0 & 0x7f800000) >> 23) - 127;
52
53 if (j0 < (int)(sizeof (long int) * 8) - 1)
54 {
55 if (j0 >= 23)
56 result = (long int) ((i0 & 0x7fffff) | 0x800000) << (j0 - 23);
57 else
58 {
59 w = TWO23[sx] + x;
60 t = w - TWO23[sx];
61 GET_FLOAT_WORD (i0, t);
62 j0 = ((i0 >> 23) & 0xff) - 0x7f;
63 i0 &= 0x7fffff;
64 i0 |= 0x800000;
65 if (j0 < 0)
66 result = 0;
67 else
68 result = i0 >> (23 - j0);
69 }
70 }
71 else
72 {
73 if (x != LONG_MIN)
74 {
75 __math_set_invalidf();
76 return sx ? LONG_MIN : LONG_MAX;
77 }
78 return (long int) x;
79 }
80 return sx ? -result : result;
81 }
82
83 _MATH_ALIAS_j_f(lrint)
84
