1*05a0b428SJohn Marino /* @(#)s_floor.c 5.1 93/09/24 */
2*05a0b428SJohn Marino /*
3*05a0b428SJohn Marino * ====================================================
4*05a0b428SJohn Marino * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5*05a0b428SJohn Marino *
6*05a0b428SJohn Marino * Developed at SunPro, a Sun Microsystems, Inc. business.
7*05a0b428SJohn Marino * Permission to use, copy, modify, and distribute this
8*05a0b428SJohn Marino * software is freely granted, provided that this notice
9*05a0b428SJohn Marino * is preserved.
10*05a0b428SJohn Marino * ====================================================
11*05a0b428SJohn Marino */
12*05a0b428SJohn Marino
13*05a0b428SJohn Marino /*
14*05a0b428SJohn Marino * trunc(x)
15*05a0b428SJohn Marino * Return x rounded toward 0 to integral value
16*05a0b428SJohn Marino * Method:
17*05a0b428SJohn Marino * Bit twiddling.
18*05a0b428SJohn Marino * Exception:
19*05a0b428SJohn Marino * Inexact flag raised if x not equal to trunc(x).
20*05a0b428SJohn Marino */
21*05a0b428SJohn Marino
22*05a0b428SJohn Marino #include <float.h>
23*05a0b428SJohn Marino #include <math.h>
24*05a0b428SJohn Marino
25*05a0b428SJohn Marino #include "math_private.h"
26*05a0b428SJohn Marino
27*05a0b428SJohn Marino static const double huge = 1.0e300;
28*05a0b428SJohn Marino
29*05a0b428SJohn Marino double
trunc(double x)30*05a0b428SJohn Marino trunc(double x)
31*05a0b428SJohn Marino {
32*05a0b428SJohn Marino int32_t i0,i1,jj0;
33*05a0b428SJohn Marino u_int32_t i;
34*05a0b428SJohn Marino EXTRACT_WORDS(i0,i1,x);
35*05a0b428SJohn Marino jj0 = ((i0>>20)&0x7ff)-0x3ff;
36*05a0b428SJohn Marino if(jj0<20) {
37*05a0b428SJohn Marino if(jj0<0) { /* raise inexact if x != 0 */
38*05a0b428SJohn Marino if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */
39*05a0b428SJohn Marino i0 &= 0x80000000U;
40*05a0b428SJohn Marino i1 = 0;
41*05a0b428SJohn Marino }
42*05a0b428SJohn Marino } else {
43*05a0b428SJohn Marino i = (0x000fffff)>>jj0;
44*05a0b428SJohn Marino if(((i0&i)|i1)==0) return x; /* x is integral */
45*05a0b428SJohn Marino if(huge+x>0.0) { /* raise inexact flag */
46*05a0b428SJohn Marino i0 &= (~i); i1=0;
47*05a0b428SJohn Marino }
48*05a0b428SJohn Marino }
49*05a0b428SJohn Marino } else if (jj0>51) {
50*05a0b428SJohn Marino if(jj0==0x400) return x+x; /* inf or NaN */
51*05a0b428SJohn Marino else return x; /* x is integral */
52*05a0b428SJohn Marino } else {
53*05a0b428SJohn Marino i = ((u_int32_t)(0xffffffff))>>(jj0-20);
54*05a0b428SJohn Marino if((i1&i)==0) return x; /* x is integral */
55*05a0b428SJohn Marino if(huge+x>0.0) /* raise inexact flag */
56*05a0b428SJohn Marino i1 &= (~i);
57*05a0b428SJohn Marino }
58*05a0b428SJohn Marino INSERT_WORDS(x,i0,i1);
59*05a0b428SJohn Marino return x;
60*05a0b428SJohn Marino }
61*05a0b428SJohn Marino
62*05a0b428SJohn Marino #if LDBL_MANT_DIG == DBL_MANT_DIG
63*05a0b428SJohn Marino __strong_alias(truncl, trunc);
64*05a0b428SJohn Marino #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */
65