/*

 * 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__ */

}