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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. | |
5 | * | |
6 | * Developed at SunPro, a Sun Microsystems, Inc. business. | |
7 | * Permission to use, copy, modify, and distribute this | |
cccda09f | 8 | * software is freely granted, provided that this notice |
f7eac6eb RM |
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 */ | |
cccda09f | 49 | if(i0>=0) {i0=i1=0;} |
f7eac6eb RM |
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) { | |
cccda09f | 69 | if(j0==20) i0+=1; |
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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 | } | |
82 | weak_alias (__floor, floor) | |
cccda09f UD |
83 | #ifdef NO_LONG_DOUBLE |
84 | strong_alias (__floor, __floorl) | |
85 | weak_alias (__floor, floorl) | |
86 | #endif |