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re PR libstdc++/33815 (tr1::uniform_int isn't uniform)

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2007-10-19  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/33815
	* include/tr1_impl/random
	(uniform_int<>::_M_call(_UniformRandomNumberGenerator&, result_type,
	result_type, true_type)): Avoid the modulo (which uses the low-order
	bits).

From-SVN: r129769
This commit is contained in:
Paolo Carlini 2007-10-30 13:05:26 +00:00
parent 19d8eb46e3
commit ebb82e2751
3 changed files with 55 additions and 21 deletions
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30
libstdc++-v3/ChangeLog
View File

@ -1,21 +1,31 @@
2007-10-30 Paolo Carlini <pcarlini@suse.de>
* include/tr1_impl/random (uniform_int<>::
_M_call(_UniformRandomNumberGenerator&, result_type, result_type,
true_type)): Only declare.
* include/tr1_impl/random.tcc (uniform_int<>::
_M_call(_UniformRandomNumberGenerator&, result_type, result_type,
true_type)): Re-do, unbiased for the currently supported ranges;
add comment.
2007-10-30 Benjamin Kosnik <bkoz@redhat.com>
*docs/html/ext/pb_ds/multimap_text_insert_timing_test_small.html:
* docs/html/ext/pb_ds/multimap_text_insert_timing_test_small.html:
Correct filename.
*docs/html/ext/pb_ds/multimap_text_find_timing_test_large.html: Same.
*docs/html/ext/pb_ds/
* docs/html/ext/pb_ds/multimap_text_find_timing_test_large.html: Same.
* docs/html/ext/pb_ds/
multimap_text_insert_mem_usage_test_small.html: Same.
*docs/html/ext/pb_ds/multimap_text_insert_timing_test_large.html: Same.
*docs/html/ext/pb_ds/
* docs/html/ext/pb_ds/multimap_text_insert_timing_test_large.html: Same.
* docs/html/ext/pb_ds/
multimap_text_insert_mem_usage_test_large.html: Same.
*docs/html/ext/pb_ds/multimap_text_find_timing_test_small.html: Same.
* docs/html/ext/pb_ds/multimap_text_find_timing_test_small.html: Same.
2007-10-30 Benjamin Kosnik <bkoz@redhat.com>
*include/Makefile.am (PCHFLAGS): Remove -Wno-deprecated.
*include/Makefile.in: Regenerate.
*include/std/memory: Remove extraneous include.
* include/Makefile.am (PCHFLAGS): Remove -Wno-deprecated.
* include/Makefile.in: Regenerate.
* include/std/memory: Remove extraneous include.
2007-10-29 Benjamin Kosnik <bkoz@redhat.com>

12
libstdc++-v3/include/tr1_impl/random
View File

@ -1603,17 +1603,7 @@ _GLIBCXX_BEGIN_NAMESPACE_TR1
template<typename _UniformRandomNumberGenerator>
result_type
_M_call(_UniformRandomNumberGenerator& __urng,
result_type __min, result_type __max, true_type)
{
// XXX Must be fixed to also work when __urng.max() - __urng.min()
// is smaller than __max - __min.
typedef typename __gnu_cxx::__add_unsigned<typename
_UniformRandomNumberGenerator::result_type>::__type __utype;
return result_type((__max - __min + 1.0L)
* (__utype(__urng()) - __utype(__urng.min()))
/ (__utype(__urng.max())
- __utype(__urng.min()) + 1.0L)) + __min;
}
result_type __min, result_type __max, true_type);
template<typename _UniformRandomNumberGenerator>
result_type

34
libstdc++-v3/include/tr1_impl/random.tcc
View File

@ -750,6 +750,40 @@ _GLIBCXX_BEGIN_NAMESPACE_TR1
}
template<typename _IntType>
template<typename _UniformRandomNumberGenerator>
typename uniform_int<_IntType>::result_type
uniform_int<_IntType>::
_M_call(_UniformRandomNumberGenerator& __urng,
result_type __min, result_type __max, true_type)
{
// XXX Must be fixed to work well for *arbitrary* __urng.max(),
// __urng.min(), __max, __min. Currently works fine only in the
// most common case __urng.max() - __urng.min() >= __max - __min,
// with __urng.max() > __urng.min() >= 0.
typedef typename __gnu_cxx::__add_unsigned<typename
_UniformRandomNumberGenerator::result_type>::__type __urntype;
typedef typename __gnu_cxx::__add_unsigned<result_type>::__type
__utype;
typedef typename __gnu_cxx::__conditional_type<(sizeof(__urntype)
> sizeof(__utype)),
__urntype, __utype>::__type __uctype;
result_type __ret;
const __urntype __urnmin = __urng.min();
const __urntype __urnmax = __urng.max();
const __urntype __urnrange = __urnmax - __urnmin;
const __uctype __urange = __max - __min;
const __uctype __udenom = (__urnrange <= __urange
? 1 : __urnrange / (__urange + 1));
do
__ret = (__urntype(__urng()) - __urnmin) / __udenom;
while (__ret > __max - __min);
return __ret + __min;
}
template<typename _IntType, typename _CharT, typename _Traits>
std::basic_ostream<_CharT, _Traits>&
operator<<(std::basic_ostream<_CharT, _Traits>& __os,