1 /* lrintf adapted to be llrintf for Newlib, 2009 by Craig Howland. */
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 * llrintf(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 llrintf(x).
22 */
23
24 #include "fdlibm.h"
25
26 static const float
27 /* Adding a float, x, to 2^23 will cause the result to be rounded based on
28 the fractional part of x, according to the implementation's current rounding
29 mode. 2^23 is the smallest float that can be represented using all 23 significant
30 digits. */
31 TWO23[2]={
32 8.3886080000e+06, /* 0x4b000000 */
33 -8.3886080000e+06, /* 0xcb000000 */
34 };
35
llrintf(float x)36 long long int llrintf(float x)
37 {
38 __int32_t j0,sx;
39 __uint32_t i0;
40 float t;
41 volatile float w;
42 long long int result;
43
44 GET_FLOAT_WORD(i0,x);
45
46 /* Extract sign bit. */
47 sx = (i0 >> 31);
48
49 /* Extract exponent field. */
50 j0 = ((i0 & 0x7f800000) >> 23) - 127;
51
52 if (j0 < (int)(sizeof (long long int) * 8) - 1)
53 {
54 if (j0 < -1)
55 return 0;
56 else if (j0 >= 23)
57 result = (long long int) ((i0 & 0x7fffff) | 0x800000) << (j0 - 23);
58 else
59 {
60 w = TWO23[sx] + x;
61 t = w - TWO23[sx];
62 GET_FLOAT_WORD (i0, t);
63 /* Detect the all-zeros representation of plus and
64 minus zero, which fails the calculation below. */
65 if ((i0 & ~((__uint32_t)1 << 31)) == 0)
66 return 0;
67 j0 = ((i0 >> 23) & 0xff) - 0x7f;
68 i0 &= 0x7fffff;
69 i0 |= 0x800000;
70 result = i0 >> (23 - j0);
71 }
72 }
73 else
74 {
75 return (long long int) x;
76 }
77 return sx ? -result : result;
78 }
79
80 _MATH_ALIAS_k_f(llrint)
81
