0712b236c3
We do need the unoptimized version of csrand_uniform() for high values of `n`, since the optimized version depends on having __int128, and it's not available on several platforms, including ARMv7, IA32, and MK68k. This reverts commit 848f53c1d3c1362c86d3baab6906e1e4419d2634; however, I applied some tweaks to the reverted commit. Reported-by: Adam Sampson <ats@offog.org> Cc: Iker Pedrosa <ipedrosa@redhat.com> Signed-off-by: Alejandro Colomar <alx@kernel.org>
49 lines
863 B
C
49 lines
863 B
C
/*
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* SPDX-FileCopyrightText: 2022 - 2023, Alejandro Colomar <alx@kernel.org>
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#ifndef SHADOW_INCLUDE_LIB_BIT_H_
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#define SHADOW_INCLUDE_LIB_BIT_H_
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#include <config.h>
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#include <limits.h>
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inline unsigned long bit_ceilul(unsigned long x);
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inline unsigned long bit_ceil_wrapul(unsigned long x);
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inline int leading_zerosul(unsigned long x);
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/* stdc_bit_ceilul(3) */
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inline unsigned long
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bit_ceilul(unsigned long x)
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{
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return 1 + (ULONG_MAX >> leading_zerosul(x));
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}
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/* stdc_bit_ceilul(3), but wrap instead of having Undefined Behavior */
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inline unsigned long
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bit_ceil_wrapul(unsigned long x)
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{
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if (x == 0)
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return 0;
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return bit_ceil_wrapul(x);
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}
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/* stdc_leading_zerosul(3) */
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inline int
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leading_zerosul(unsigned long x)
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{
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return (x == 0) ? ULONG_WIDTH : __builtin_clz(x);
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}
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#endif // include guard
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