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6c010c5dde
In TS 18661-1, getpayload had an unspecified return value for a non-NaN argument, while C2x requires the return value -1 in that case. This patch implements the return value of -1. I don't think this is worth having a new symbol version that's an alias of the old one, although occasionally we do that in such cases where the new function semantics are a refinement of the old ones (to avoid programs relying on the new semantics running on older glibc versions but not behaving as intended). Tested for x86_64 and x86; also ran math/ tests for aarch64 and powerpc.
63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
/* Get NaN payload. ldbl-128 version.
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Copyright (C) 2016-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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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 <stdint.h>
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_Float128
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__getpayloadl (const _Float128 *x)
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{
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uint64_t hx, lx;
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GET_LDOUBLE_WORDS64 (hx, lx, *x);
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if ((hx & 0x7fff000000000000ULL) != 0x7fff000000000000ULL
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|| ((hx & 0xffffffffffffULL) | lx) == 0)
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return -1;
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hx &= 0x7fffffffffffULL;
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/* Construct the representation of the return value directly, since
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128-bit integers may not be available. */
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int lz;
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if (hx == 0)
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{
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if (lx == 0)
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return 0.0L;
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else
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lz = __builtin_clzll (lx) + 64;
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}
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else
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lz = __builtin_clzll (hx);
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int shift = lz - 15;
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if (shift >= 64)
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{
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hx = lx << (shift - 64);
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lx = 0;
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}
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else
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{
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/* 2 <= SHIFT <= 63. */
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hx = (hx << shift) | (lx >> (64 - shift));
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lx <<= shift;
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}
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hx = (hx & 0xffffffffffffULL) | ((0x3fffULL + 127 - lz) << 48);
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_Float128 ret;
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SET_LDOUBLE_WORDS64 (ret, hx, lx);
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return ret;
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}
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libm_alias_ldouble (__getpayload, getpayload)
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