+2012-01-27 Paolo Carlini <paolo.carlini@oracle.com>
+
+ PR libstdc++/51795
+ * include/bits/random.h (linear_congruential_generator): Add
+ static_assert preventing instantiation for values of 'a' and 'm'
+ currently handled incorrectly but _Mod::__calc.
+ * include/bits/random.tcc (seed_seq::generate): Avoid unsafe
+ uses of _Mod::__calc.
+
2012-01-27 Jakub Jelinek <jakub@redhat.com>
PR libstdc++/51798
// random number generation -*- C++ -*-
-// Copyright (C) 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright (C) 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
static_assert(__m == 0u || (__a < __m && __c < __m),
"template argument substituting __m out of bounds");
+ // XXX FIXME:
+ // _Mod::__calc should handle correctly __m % __a >= __m / __a too.
+ static_assert(__m % __a < __m / __a,
+ "sorry, not implemented yet: try a smaller 'a' constant");
+
public:
/** The type of the generated random value. */
typedef _UIntType result_type;
// random number generation (out of line) -*- C++ -*-
-// Copyright (C) 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright (C) 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
//
// Preconditions: a > 0, m > 0.
//
+ // XXX FIXME: as-is, only works correctly for __m % __a < __m / __a.
+ //
template<typename _Tp, _Tp __m, _Tp __a, _Tp __c, bool>
struct _Mod
{
^ __begin[(__k + __p) % __n]
^ __begin[(__k - 1) % __n]);
_Type __r1 = __arg ^ (__arg >> 27);
- __r1 = __detail::__mod<_Type, __detail::_Shift<_Type, 32>::__value,
- 1664525u, 0u>(__r1);
+ __r1 = __detail::__mod<_Type,
+ __detail::_Shift<_Type, 32>::__value>(1664525u * __r1);
_Type __r2 = __r1;
if (__k == 0)
__r2 += __s;
+ __begin[(__k + __p) % __n]
+ __begin[(__k - 1) % __n]);
_Type __r3 = __arg ^ (__arg >> 27);
- __r3 = __detail::__mod<_Type, __detail::_Shift<_Type, 32>::__value,
- 1566083941u, 0u>(__r3);
+ __r3 = __detail::__mod<_Type,
+ __detail::_Shift<_Type, 32>::__value>(1566083941u * __r3);
_Type __r4 = __r3 - __k % __n;
__r4 = __detail::__mod<_Type,
__detail::_Shift<_Type, 32>::__value>(__r4);