Update.
[glibc.git] / sysdeps / libm-ieee754 / s_floor.c
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1 /* @(#)s_floor.c 5.1 93/09/24 */
2 /*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 * ====================================================
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
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).
26 #include "math.h"
27 #include "math_private.h"
29 #ifdef __STDC__
30 static const double huge = 1.0e300;
31 #else
32 static double huge = 1.0e300;
33 #endif
35 #ifdef __STDC__
36 double __floor(double x)
37 #else
38 double __floor(x)
39 double x;
40 #endif
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;}
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;
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;
76 i1 &= (~i);
79 INSERT_WORDS(x,i0,i1);
80 return x;
82 weak_alias (__floor, floor)
83 #ifdef NO_LONG_DOUBLE
84 strong_alias (__floor, __floorl)
85 weak_alias (__floor, floorl)
86 #endif