release 1.80beta1 for pandora
[picodrive.git] / platform / gp2x / code940 / uClibc / s_floor.c
1 /* @(#)s_floor.c 5.1 93/09/24 */
2 /*
3  * ====================================================
4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5  *
6  * Developed at SunPro, a Sun Microsystems, Inc. business.
7  * Permission to use, copy, modify, and distribute this
8  * software is freely granted, provided that this notice
9  * is preserved.
10  * ====================================================
11  */
12
13 #if defined(LIBM_SCCS) && !defined(lint)
14 static char rcsid[] = "$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $";
15 #endif
16
17 /*
18  * floor(x)
19  * Return x rounded toward -inf to integral value
20  * Method:
21  *      Bit twiddling.
22  * Exception:
23  *      Inexact flag raised if x not equal to floor(x).
24  */
25
26 #include "math.h"
27 #include "math_private.h"
28
29 #ifdef __STDC__
30 static const double huge = 1.0e300;
31 #else
32 static double huge = 1.0e300;
33 #endif
34
35 #ifdef __STDC__
36         double floor(double x)
37 #else
38         double floor(x)
39         double x;
40 #endif
41 {
42         int32_t i0,i1,j0;
43         u_int32_t i,j;
44         EXTRACT_WORDS(i0,i1,x);
45         j0 = ((i0>>20)&0x7ff)-0x3ff;
46         if(j0<20) {
47             if(j0<0) {  /* raise inexact if x != 0 */
48                 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
49                     if(i0>=0) {i0=i1=0;}
50                     else if(((i0&0x7fffffff)|i1)!=0)
51                         { i0=0xbff00000;i1=0;}
52                 }
53             } else {
54                 i = (0x000fffff)>>j0;
55                 if(((i0&i)|i1)==0) return x; /* x is integral */
56                 if(huge+x>0.0) {        /* raise inexact flag */
57                     if(i0<0) i0 += (0x00100000)>>j0;
58                     i0 &= (~i); i1=0;
59                 }
60             }
61         } else if (j0>51) {
62             if(j0==0x400) return x+x;   /* inf or NaN */
63             else return x;              /* x is integral */
64         } else {
65             i = ((u_int32_t)(0xffffffff))>>(j0-20);
66             if((i1&i)==0) return x;     /* x is integral */
67             if(huge+x>0.0) {            /* raise inexact flag */
68                 if(i0<0) {
69                     if(j0==20) i0+=1;
70                     else {
71                         j = i1+(1<<(52-j0));
72                         if(j<i1) i0 +=1 ;       /* got a carry */
73                         i1=j;
74                     }
75                 }
76                 i1 &= (~i);
77             }
78         }
79         INSERT_WORDS(x,i0,i1);
80         return x;
81 }