| 1 | /* @(#)s_ceil.c 5.1 93/09/24 */
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| 2 | /*
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| 3 | * ====================================================
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| 4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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| 5 | *
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| 6 | * Developed at SunPro, a Sun Microsystems, Inc. business.
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| 7 | * Permission to use, copy, modify, and distribute this
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| 8 | * software is freely granted, provided that this notice
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| 9 | * is preserved.
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| 10 | * ====================================================
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| 11 | */
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| 12 |
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| 13 | #ifndef lint
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| 14 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_ceil.c,v 1.9 2003/07/23 04:53:46 peter Exp $";
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| 15 | #endif
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| 16 |
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| 17 | /*
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| 18 | * ceil(x)
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| 19 | * Return x rounded toward -inf to integral value
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| 20 | * Method:
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| 21 | * Bit twiddling.
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| 22 | * Exception:
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| 23 | * Inexact flag raised if x not equal to ceil(x).
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| 24 | */
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| 25 |
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| 26 | #include "math.h"
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| 27 | #include "math_private.h"
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| 28 |
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| 29 | static const double huge = 1.0e300;
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| 30 |
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| 31 | double
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| 32 | ceil(double x)
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| 33 | {
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| 34 | int32_t i0,i1,j0;
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| 35 | u_int32_t i,j;
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| 36 | EXTRACT_WORDS(i0,i1,x);
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| 37 | j0 = ((i0>>20)&0x7ff)-0x3ff;
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| 38 | if(j0<20) {
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| 39 | if(j0<0) { /* raise inexact if x != 0 */
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| 40 | if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
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| 41 | if(i0<0) {i0=0x80000000;i1=0;}
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| 42 | else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;}
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| 43 | }
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| 44 | } else {
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| 45 | i = (0x000fffff)>>j0;
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| 46 | if(((i0&i)|i1)==0) return x; /* x is integral */
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| 47 | if(huge+x>0.0) { /* raise inexact flag */
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| 48 | if(i0>0) i0 += (0x00100000)>>j0;
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| 49 | i0 &= (~i); i1=0;
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| 50 | }
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| 51 | }
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| 52 | } else if (j0>51) {
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| 53 | if(j0==0x400) return x+x; /* inf or NaN */
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| 54 | else return x; /* x is integral */
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| 55 | } else {
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| 56 | i = ((u_int32_t)(0xffffffff))>>(j0-20);
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| 57 | if((i1&i)==0) return x; /* x is integral */
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| 58 | if(huge+x>0.0) { /* raise inexact flag */
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| 59 | if(i0>0) {
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| 60 | if(j0==20) i0+=1;
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| 61 | else {
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| 62 | j = i1 + (1<<(52-j0));
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| 63 | if(j<i1) i0+=1; /* got a carry */
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| 64 | i1 = j;
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| 65 | }
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| 66 | }
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| 67 | i1 &= (~i);
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| 68 | }
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| 69 | }
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| 70 | INSERT_WORDS(x,i0,i1);
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| 71 | return x;
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| 72 | }
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