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72 lines
1.7 KiB
C
72 lines
1.7 KiB
C
/*
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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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* From: @(#)s_floor.c 5.1 93/09/24
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*/
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/*
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* truncl(x)
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* Return x rounded toward 0 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 truncl(x).
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*/
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#include <sys/types.h>
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#include <machine/ieee.h>
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#include <float.h>
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#include <openlibm.h>
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#include <stdint.h>
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#include "math_private.h"
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#ifdef LDBL_IMPLICIT_NBIT
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#define MANH_SIZE (EXT_FRACHBITS + EXT_FRACHMBITS + 1)
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#else
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#define MANH_SIZE (EXT_FRACHBITS + EXT_FRACHMBITS)
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#endif
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static const long double huge = 1.0e300;
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static const float zero[] = { 0.0, -0.0 };
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long double
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truncl(long double x)
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{
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int e;
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int64_t ix0, ix1;
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GET_LDOUBLE_WORDS64(ix0,ix1,x);
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e = ((ix0>>48)&0x7fff) - LDBL_MAX_EXP + 1;
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if (e < MANH_SIZE - 1) {
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if (e < 0) { /* raise inexact if x != 0 */
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if (huge + x > 0.0)
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return (zero[((ix0>>48)&0x8000)!=0]);
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} else {
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uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
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if (((ix0 & m) | ix1) == 0)
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return (x); /* x is integral */
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if (huge + x > 0.0) { /* raise inexact flag */
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ix0 &= ~m;
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ix1 = 0;
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}
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}
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} else if (e < LDBL_MANT_DIG - 1) {
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uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
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if ((ix1 & m) == 0)
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return (x); /* x is integral */
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if (huge + x > 0.0) /* raise inexact flag */
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ix1 &= ~m;
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}
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SET_LDOUBLE_WORDS64(x,ix0,ix1);
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return (x);
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}
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