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/*
+----------------------------------------------------------------------+
| HipHop for PHP |
+----------------------------------------------------------------------+
| Copyright (c) 2010- Facebook, Inc. (http://www.facebook.com) |
+----------------------------------------------------------------------+
| This source file is subject to version 3.01 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| http://www.php.net/license/3_01.txt |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
*/
#ifndef incl_BITOPS_H_
#define incl_BITOPS_H_
namespace HPHP {
// GLIBC doesn't provide an fls primitive. Since we're rolling our own
// anyway, fix ffs's wacky offset-by-one historical implementation. These
// guys return success/failure (failure for input of all zeros) and the
// unoffset bit position in their reference param.
template<typename I64>
inline bool
ffs64(I64 input, I64 &out) {
bool retval;
asm volatile("bsfq %2, %1;\n\t"
"setnz %0;\n\t"
: "=r"(retval), "=r"(out)
: "r"(input));
return retval;
}
template<typename I64>
inline bool
fls64(I64 input, I64 &out) {
bool retval;
asm volatile("bsrq %2, %1;\n\t"
"setnz %0;\n\t"
: "=r"(retval), "=r"(out)
: "r"(input));
return retval;
}
} // HPHP
#endif
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