129 lines
4.0 KiB
C
129 lines
4.0 KiB
C
/* s_nextafterl.c -- long double version of s_nextafter.c.
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* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
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*/
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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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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/* IEEE functions
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* nextafterl(x,y)
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* return the next machine floating-point number of x in the
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* direction toward y.
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* Special cases:
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*/
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#include <math.h>
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#include <math_private.h>
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#include <math_ldbl_opt.h>
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long double __nextafterl(long double x, long double y)
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{
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int64_t hx,hy,ihx,ihy;
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uint64_t lx;
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double xhi, xlo, yhi;
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ldbl_unpack (x, &xhi, &xlo);
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EXTRACT_WORDS64 (hx, xhi);
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EXTRACT_WORDS64 (lx, xlo);
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yhi = ldbl_high (y);
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EXTRACT_WORDS64 (hy, yhi);
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ihx = hx&0x7fffffffffffffffLL; /* |hx| */
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ihy = hy&0x7fffffffffffffffLL; /* |hy| */
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if((ihx>0x7ff0000000000000LL) || /* x is nan */
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(ihy>0x7ff0000000000000LL)) /* y is nan */
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return x+y; /* signal the nan */
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if(x==y)
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return y; /* x=y, return y */
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if(ihx == 0) { /* x == 0 */
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long double u; /* return +-minsubnormal */
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hy = (hy & 0x8000000000000000ULL) | 1;
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INSERT_WORDS64 (yhi, hy);
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x = yhi;
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u = math_opt_barrier (x);
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u = u * u;
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math_force_eval (u); /* raise underflow flag */
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return x;
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}
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long double u;
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if(x > y) { /* x > y, x -= ulp */
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/* This isn't the largest magnitude correctly rounded
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long double as you can see from the lowest mantissa
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bit being zero. It is however the largest magnitude
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long double with a 106 bit mantissa, and nextafterl
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is insane with variable precision. So to make
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nextafterl sane we assume 106 bit precision. */
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if((hx==0xffefffffffffffffLL)&&(lx==0xfc8ffffffffffffeLL))
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return x+x; /* overflow, return -inf */
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if (hx >= 0x7ff0000000000000LL) {
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u = 0x1.fffffffffffff7ffffffffffff8p+1023L;
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return u;
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}
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if(ihx <= 0x0360000000000000LL) { /* x <= LDBL_MIN */
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u = math_opt_barrier (x);
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x -= __LDBL_DENORM_MIN__;
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if (ihx < 0x0360000000000000LL
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|| (hx > 0 && (int64_t) lx <= 0)
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|| (hx < 0 && (int64_t) lx > 1)) {
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u = u * u;
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math_force_eval (u); /* raise underflow flag */
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}
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return x;
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}
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if (ihx < 0x06a0000000000000LL) { /* ulp will denormal */
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INSERT_WORDS64 (yhi, hx & (0x7ffLL<<52));
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u = yhi;
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u *= 0x1.0000000000000p-105L;
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} else {
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INSERT_WORDS64 (yhi, (hx & (0x7ffLL<<52))-(0x069LL<<52));
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u = yhi;
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}
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return x - u;
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} else { /* x < y, x += ulp */
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if((hx==0x7fefffffffffffffLL)&&(lx==0x7c8ffffffffffffeLL))
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return x+x; /* overflow, return +inf */
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if ((uint64_t) hx >= 0xfff0000000000000ULL) {
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u = -0x1.fffffffffffff7ffffffffffff8p+1023L;
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return u;
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}
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if(ihx <= 0x0360000000000000LL) { /* x <= LDBL_MIN */
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u = math_opt_barrier (x);
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x += __LDBL_DENORM_MIN__;
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if (ihx < 0x0360000000000000LL
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|| (hx > 0 && (int64_t) lx < 0 && lx != 0x8000000000000001LL)
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|| (hx < 0 && (int64_t) lx >= 0)) {
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u = u * u;
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math_force_eval (u); /* raise underflow flag */
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}
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if (x == 0.0L) /* handle negative __LDBL_DENORM_MIN__ case */
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x = -0.0L;
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return x;
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}
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if (ihx < 0x06a0000000000000LL) { /* ulp will denormal */
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INSERT_WORDS64 (yhi, hx & (0x7ffLL<<52));
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u = yhi;
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u *= 0x1.0000000000000p-105L;
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} else {
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INSERT_WORDS64 (yhi, (hx & (0x7ffLL<<52))-(0x069LL<<52));
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u = yhi;
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}
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return x + u;
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}
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}
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strong_alias (__nextafterl, __nexttowardl)
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long_double_symbol (libm, __nextafterl, nextafterl);
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long_double_symbol (libm, __nexttowardl, nexttowardl);
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