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/*
* Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip.
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <config.h>
#include <assert.h>
#include "roken.h"
#if defined(_MSC_VER)
#include <intrin.h>
#if defined(_WIN64)
#pragma intrinsic(_BitScanReverse64)
#else
#pragma intrinsic(_BitScanReverse)
#endif
#endif
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
rk_clzll(uint64_t x)
{
#if defined(_MSC_VER)
unsigned long r = 0;
#elif !(defined(__GNUC__) && __GNUC__ >= 4)
int r = 0;
#endif
assert(x != 0);
#if defined(_MSC_VER)
# if defined(_WIN64)
_BitScanReverse64(&r, x);
# else
if (_BitScanReverse(&r, (uint32_t)(x >> 32)))
return 63 - (r + 32);
_BitScanReverse(&r, (uint32_t)(x & 0xFFFFFFFF));
# endif
return 63 - r;
#elif (defined(__GNUC__) && __GNUC__ >= 4)
return __builtin_clzll(x);
#else
while (!(x & ((uint64_t)1 << 63))) {
x <<= 1;
++r;
}
return r;
#endif /* _MSC_VER || __GNUC__ */
}
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