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// bits.h
/* Copyright 2012 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
// figure out if we're on a 64 or 32 bit system
#if defined(__x86_64__) || defined(__amd64__) || defined(_WIN64) || defined(__aarch64__) || defined(__powerpc64__)
#define MONGO_PLATFORM_64
#elif defined(__i386__) || defined(_WIN32) || defined(__arm__)
#define MONGO_PLATFORM_32
#else
#error "unknown platform"
#endif
namespace mongo {
// defined here so can test on linux
inline int mongo_firstBitSet( unsigned long long v ) {
if ( v == 0 )
return 0;
for ( int i = 0; i<8; i++ ) {
unsigned long long x = ( v >> ( 8 * i ) ) & 0xFF;
if ( x == 0 )
continue;
for ( int j = 0; j < 8; j++ ) {
if ( ( x >> j ) & 0x1 )
return ( i * 8 ) + j + 1;
}
}
return 0;
}
}
#if defined(__linux__)
#define firstBitSet ffsll
#define MONGO_SYSTEM_FFS 1
#elif defined(__MACH__) && defined(MONGO_PLATFORM_64)
#define firstBitSet ffsl
#define MONGO_SYSTEM_FFS 1
#else
#define firstBitSet mongo::mongo_firstBitSet
#endif
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