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2e2485ce05
This patch is using the corresponding GCC builtin for logbf, logb, logbl and logbf128 if the USE_FUNCTION_BUILTIN macros are defined to one in math-use-builtins-function.h. Co-Authored-By: Xi Ruoyao <xry111@xry111.site>
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
/* s_logbl.c -- long double version of s_logb.c.
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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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/*
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* long double logbl(x)
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* IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
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* Use ilogb instead.
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*/
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#include <math.h>
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#include <math_private.h>
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#include <libm-alias-ldouble.h>
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#include <math-use-builtins.h>
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_Float128
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__logbl (_Float128 x)
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{
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#if USE_LOGBL_BUILTIN
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return __builtin_logbl (x);
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#else
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/* Use generic implementation. */
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int64_t lx, hx, ex;
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GET_LDOUBLE_WORDS64 (hx, lx, x);
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hx &= 0x7fffffffffffffffLL; /* high |x| */
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if ((hx | lx) == 0)
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return -1.0 / fabsl (x);
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if (hx >= 0x7fff000000000000LL)
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return x * x;
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if ((ex = hx >> 48) == 0) /* IEEE 754 logb */
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{
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/* POSIX specifies that denormal number is treated as
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though it were normalized. */
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int ma;
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if (hx == 0)
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ma = __builtin_clzll (lx) + 64;
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else
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ma = __builtin_clzll (hx);
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ex -= ma - 16;
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}
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return (_Float128) (ex - 16383);
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#endif /* ! USE_LOGBL_BUILTIN */
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}
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libm_alias_ldouble (__logb, logb)
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