Annotation of src/lib/libm/src/s_ceil.c, Revision 1.14
1.1 jtc 1: /* @(#)s_ceil.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
1.10 simonb 8: * software is freely granted, provided that this notice
1.1 jtc 9: * is preserved.
10: * ====================================================
11: */
1.3 jtc 12:
1.9 lukem 13: #include <sys/cdefs.h>
1.7 jtc 14: #if defined(LIBM_SCCS) && !defined(lint)
1.14 ! joerg 15: __RCSID("$NetBSD: s_ceil.c,v 1.13 2009/02/16 01:22:18 lukem Exp $");
1.3 jtc 16: #endif
1.1 jtc 17:
18: /*
19: * ceil(x)
20: * Return x rounded toward -inf to integral value
21: * Method:
22: * Bit twiddling.
23: * Exception:
24: * Inexact flag raised if x not equal to ceil(x).
25: */
26:
1.5 jtc 27: #include "math.h"
28: #include "math_private.h"
1.1 jtc 29:
1.4 jtc 30: static const double huge = 1.0e300;
1.1 jtc 31:
1.14 ! joerg 32: #ifndef __HAVE_LONG_DOUBLE
! 33: __strong_alias(_ceill, ceil)
! 34: __weak_alias(ceill, ceil)
! 35: #endif
! 36:
1.11 wiz 37: double
38: ceil(double x)
1.1 jtc 39: {
1.12 christos 40: int32_t i0,i1,jj0;
1.6 jtc 41: u_int32_t i,j;
1.5 jtc 42: EXTRACT_WORDS(i0,i1,x);
1.12 christos 43: jj0 = ((i0>>20)&0x7ff)-0x3ff;
44: if(jj0<20) {
45: if(jj0<0) { /* raise inexact if x != 0 */
1.1 jtc 46: if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
1.10 simonb 47: if(i0<0) {i0=0x80000000;i1=0;}
1.1 jtc 48: else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;}
49: }
50: } else {
1.12 christos 51: i = (0x000fffff)>>jj0;
1.1 jtc 52: if(((i0&i)|i1)==0) return x; /* x is integral */
53: if(huge+x>0.0) { /* raise inexact flag */
1.12 christos 54: if(i0>0) i0 += (0x00100000)>>jj0;
1.1 jtc 55: i0 &= (~i); i1=0;
56: }
57: }
1.12 christos 58: } else if (jj0>51) {
59: if(jj0==0x400) return x+x; /* inf or NaN */
1.1 jtc 60: else return x; /* x is integral */
61: } else {
1.12 christos 62: i = ((u_int32_t)(0xffffffff))>>(jj0-20);
1.1 jtc 63: if((i1&i)==0) return x; /* x is integral */
64: if(huge+x>0.0) { /* raise inexact flag */
65: if(i0>0) {
1.12 christos 66: if(jj0==20) i0+=1;
1.1 jtc 67: else {
1.12 christos 68: j = i1 + (1<<(52-jj0));
1.13 lukem 69: if(j<(u_int32_t)i1) i0+=1; /* got a carry */
1.1 jtc 70: i1 = j;
71: }
72: }
73: i1 &= (~i);
74: }
75: }
1.5 jtc 76: INSERT_WORDS(x,i0,i1);
1.1 jtc 77: return x;
78: }
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