From 23e8722aedfa0fbde8325a8bc5ca3394ff03d13d Mon Sep 17 00:00:00 2001 From: Paolo Carlini Date: Fri, 19 Oct 2007 17:36:03 +0000 Subject: [PATCH] re PR libstdc++/33815 (tr1::uniform_int isn't uniform) 2007-10-19 Paolo Carlini 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 --- libstdc++-v3/ChangeLog | 8 ++++++++ libstdc++-v3/include/tr1_impl/random | 6 +++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index b12b8b38306..b4f58acbc09 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,11 @@ +2007-10-19 Paolo Carlini + + 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 * include/bits/stl_algobase.h (struct __cm_assign, diff --git a/libstdc++-v3/include/tr1_impl/random b/libstdc++-v3/include/tr1_impl/random index e855307dace..f44b17f9792 100644 --- a/libstdc++-v3/include/tr1_impl/random +++ b/libstdc++-v3/include/tr1_impl/random @@ -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::__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