Line data    Source code

       1             : /*
       2             :  * Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip.
       3             :  * All rights reserved.
       4             :  *
       5             :  * Permission is hereby granted, free of charge, to any person obtaining a copy
       6             :  * of this software and associated documentation files (the "Software"), to deal
       7             :  * in the Software without restriction, including without limitation the rights
       8             :  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
       9             :  * copies of the Software, and to permit persons to whom the Software is
      10             :  * furnished to do so, subject to the following conditions:
      11             :  *
      12             :  * The above copyright notice and this permission notice shall be included in
      13             :  * all copies or substantial portions of the Software.
      14             :  *
      15             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
      16             :  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      17             :  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
      18             :  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      19             :  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
      20             :  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
      21             :  * THE SOFTWARE.
      22             :  */
      23             : 
      24             : #include <config.h>
      25             : #include <assert.h>
      26             : 
      27             : #include "roken.h"
      28             : 
      29             : #if defined(_MSC_VER)
      30             : #include <intrin.h>
      31             : #if defined(_WIN64)
      32             : #pragma intrinsic(_BitScanReverse64)
      33             : #else
      34             : #pragma intrinsic(_BitScanReverse)
      35             : #endif
      36             : #endif
      37             : 
      38             : ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
      39           0 : rk_clzll(uint64_t x)
      40             : {
      41             : #if defined(_MSC_VER)
      42             :     unsigned long r = 0;
      43             : #elif !(defined(__GNUC__) && __GNUC__ >= 4)
      44             :     int r = 0;
      45             : #endif
      46             : 
      47           0 :     assert(x != 0);
      48             : 
      49             : #if defined(_MSC_VER)
      50             : # if defined(_WIN64)
      51             :     _BitScanReverse64(&r, x);
      52             : # else
      53             :     if (_BitScanReverse(&r, (uint32_t)(x >> 32)))
      54             :         return 63 - (r + 32);
      55             :     _BitScanReverse(&r, (uint32_t)(x & 0xFFFFFFFF));
      56             : # endif
      57             : 
      58             :     return 63 - r;
      59             : #elif (defined(__GNUC__) && __GNUC__ >= 4)
      60           0 :     return __builtin_clzll(x);
      61             : #else
      62             :     while (!(x & ((uint64_t)1 << 63))) {
      63             :         x <<= 1;
      64             :         ++r;
      65             :     }
      66             : 
      67             :     return r;
      68             : #endif /* _MSC_VER || __GNUC__ */
      69             : }