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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: r129493
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Paolo Carlini 2007-10-19 17:36:03 +00:00 committed by Paolo Carlini
parent 3c167a8bbb
commit 23e8722aed
2 changed files with 13 additions and 1 deletions
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8
libstdc++-v3/ChangeLog
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@ -1,3 +1,11 @@
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).
2007-10-19 Paolo Carlini <pcarlini@suse.de>
* include/bits/stl_algobase.h (struct __cm_assign,

6
libstdc++-v3/include/tr1_impl/random
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@ -1605,9 +1605,13 @@ _GLIBCXX_BEGIN_NAMESPACE_TR1
_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(__utype(__urng()) % (__max - __min + 1)) + __min;
return result_type((__max - __min + 1.0L) * __utype(__urng())
/ (__utype(__urng.max())
- __utype(__urng.min()) + 1.0L)) + __min;
}
template<typename _UniformRandomNumberGenerator>