Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 99 | pmbaty | 1 | /* |
| 2 | Texel - A UCI chess engine. |
||
| 3 | Copyright (C) 2012-2014 Peter Österlund, peterosterlund2@gmail.com |
||
| 4 | |||
| 5 | This program is free software: you can redistribute it and/or modify |
||
| 6 | it under the terms of the GNU General Public License as published by |
||
| 7 | the Free Software Foundation, either version 3 of the License, or |
||
| 8 | (at your option) any later version. |
||
| 9 | |||
| 10 | This program is distributed in the hope that it will be useful, |
||
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
||
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
||
| 13 | GNU General Public License for more details. |
||
| 14 | |||
| 15 | You should have received a copy of the GNU General Public License |
||
| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
||
| 17 | */ |
||
| 18 | |||
| 19 | /* |
||
| 20 | * util.cpp |
||
| 21 | * |
||
| 22 | * Created on: Mar 2, 2012 |
||
| 23 | * Author: petero |
||
| 24 | */ |
||
| 25 | |||
| 26 | #include "util.hpp" |
||
| 27 | |||
| 28 | static const int firstBitTable[32] = { |
||
| 29 | 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, |
||
| 30 | 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 |
||
| 31 | }; |
||
| 32 | |||
| 33 | int floorLog2(U32 x) { |
||
| 34 | x |= x >> 1; |
||
| 35 | x |= x >> 2; |
||
| 36 | x |= x >> 4; |
||
| 37 | x |= x >> 8; |
||
| 38 | x |= x >> 16; |
||
| 39 | return firstBitTable[(x * (U32)0x07c4acdd) >> 27]; |
||
| 40 | } |