mirror of https://github.com/PCSX2/pcsx2.git
42 lines
1.3 KiB
C
42 lines
1.3 KiB
C
/* PCSX2 - PS2 Emulator for PCs
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* Copyright (C) 2014- PCSX2 Dev Team
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*
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* PCSX2 is free software: you can redistribute it and/or modify it under the terms
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* of the GNU Lesser General Public License as published by the Free Software Found-
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* ation, either version 3 of the License, or (at your option) any later version.
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*
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* PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with PCSX2.
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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// Hopefully this file will be used for cross-source math utilities.
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// Currently these are strewn across the code base. Please collect them all!
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#include "common/Pcsx2Defs.h"
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// On GCC >= 4.7, this is equivalent to __builtin_clrsb(n);
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inline u32 count_leading_sign_bits(s32 n)
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{
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// If the sign bit is 1, we invert the bits to 0 for count-leading-zero.
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if (n < 0)
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n = ~n;
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// If BSR is used directly, it would have an undefined value for 0.
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if (n == 0)
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return 32;
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// Perform our count leading zero.
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#ifdef _MSC_VER
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unsigned long ret;
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_BitScanReverse(&ret, n);
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return 31 - (u32)ret;
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#else
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return __builtin_clz(n);
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#endif
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}
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