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71 lines
1.6 KiB
C
71 lines
1.6 KiB
C
/* @(#)s_floor.c 5.1 93/09/24 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* floorl(x)
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* Return x rounded toward -inf to integral value
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* Method:
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* Bit twiddling.
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* Exception:
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* Inexact flag raised if x not equal to floor(x).
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*/
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#include <math.h>
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#include "math_private.h"
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static const long double huge = 1.0e4930L;
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long double
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floorl(long double x)
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{
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int64_t i0,i1,jj0;
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u_int64_t i,j;
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GET_LDOUBLE_WORDS64(i0,i1,x);
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jj0 = ((i0>>48)&0x7fff)-0x3fff;
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if(jj0<48) {
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if(jj0<0) { /* raise inexact if x != 0 */
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if(huge+x>0.0) {
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if(i0>=0)
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return 0.0L;
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else if(((i0&0x7fffffffffffffffLL)|i1)!=0)
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return -1.0L;
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}
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} else {
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i = (0x0000ffffffffffffULL)>>jj0;
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if(((i0&i)|i1)==0) return x; /* x is integral */
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if(huge+x>0.0) { /* raise inexact flag */
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if(i0<0) i0 += (0x0001000000000000LL)>>jj0;
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i0 &= (~i); i1=0;
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}
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}
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} else if (jj0>111) {
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if(jj0==0x4000) return x+x; /* inf or NaN */
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else return x; /* x is integral */
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} else {
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i = -1ULL>>(jj0-48);
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if((i1&i)==0) return x; /* x is integral */
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if(huge+x>0.0) { /* raise inexact flag */
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if(i0<0) {
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if(jj0==48) i0+=1;
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else {
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j = i1+(1LL<<(112-jj0));
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if(j<i1) i0 +=1 ; /* got a carry */
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i1=j;
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}
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}
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i1 &= (~i);
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}
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}
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SET_LDOUBLE_WORDS64(x,i0,i1);
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return x;
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}
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