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| author | Paolo Carlini <pcarlini@suse.de> | 2007-10-25 10:11:58 +0000 |
|---|---|---|
| committer | Paolo Carlini <paolo@gcc.gnu.org> | 2007-10-25 10:11:58 +0000 |
| commit | 1fcd0a2c503b9fd16cf52df248c92c387d0086f9 (patch) | |
| tree | 8efb128e5310c8415d98d1187fdc6278b1416e37 | |
| parent | 0bf2cf8907a382fd2223ac0975516ab99283eaa8 (diff) | |
| download | gcc-1fcd0a2c503b9fd16cf52df248c92c387d0086f9.zip gcc-1fcd0a2c503b9fd16cf52df248c92c387d0086f9.tar.gz gcc-1fcd0a2c503b9fd16cf52df248c92c387d0086f9.tar.bz2 | |
stl_algo.h (__lg<>(_Size)): Slightly tweak.
2007-10-25 Paolo Carlini <pcarlini@suse.de>
* include/bits/stl_algo.h (__lg<>(_Size)): Slightly tweak.
(__lg(int), __lg(long), __lg(long long)): Add, overloads
exploiting __builtin_clz*.
From-SVN: r129624
| -rw-r--r-- | libstdc++-v3/ChangeLog | 6 | ||||
| -rw-r--r-- | libstdc++-v3/include/bits/stl_algo.h | 18 |
2 files changed, 21 insertions, 3 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 3616d36..fabbe8a 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,9 @@ +2007-10-25 Paolo Carlini <pcarlini@suse.de> + + * include/bits/stl_algo.h (__lg<>(_Size)): Slightly tweak. + (__lg(int), __lg(long), __lg(long long)): Add, overloads + exploiting __builtin_clz*. + 2007-10-24 Paolo Carlini <pcarlini@suse.de> * include/tr1_impl/array (_M_instance): Align naturally. diff --git a/libstdc++-v3/include/bits/stl_algo.h b/libstdc++-v3/include/bits/stl_algo.h index dd6d7f3..d254ec6 100644 --- a/libstdc++-v3/include/bits/stl_algo.h +++ b/libstdc++-v3/include/bits/stl_algo.h @@ -2085,7 +2085,7 @@ _GLIBCXX_BEGIN_NAMESPACE(std) /** * @if maint - * This is a helper function for the sort routines. + * This is a helper function for the sort routines. Precondition: __n > 0. * @endif */ template<typename _Size> @@ -2093,11 +2093,23 @@ _GLIBCXX_BEGIN_NAMESPACE(std) __lg(_Size __n) { _Size __k; - for (__k = 0; __n != 1; __n >>= 1) + for (__k = 0; __n != 0; __n >>= 1) ++__k; - return __k; + return __k - 1; } + inline int + __lg(int __n) + { return sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); } + + inline long + __lg(long __n) + { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); } + + inline long long + __lg(long long __n) + { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); } + // sort template<typename _RandomAccessIterator, typename _Size> |