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-rw-r--r--src/corelib/global/qrandom.h134
1 files changed, 74 insertions, 60 deletions
diff --git a/src/corelib/global/qrandom.h b/src/corelib/global/qrandom.h
index 4e27ef1edc..f8e53f4009 100644
--- a/src/corelib/global/qrandom.h
+++ b/src/corelib/global/qrandom.h
@@ -1,46 +1,10 @@
-/****************************************************************************
-**
-** Copyright (C) 2017 Intel Corporation.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtCore module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
+// Copyright (C) 2020 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QRANDOM_H
#define QRANDOM_H
-#include <QtCore/qglobal.h>
+#include <QtCore/qalgorithms.h>
#include <algorithm> // for std::generate
#include <random> // for std::mt19937
@@ -83,16 +47,12 @@ public:
quint32 generate()
{
- quint32 ret;
- fillRange(&ret, 1);
- return ret;
+ return quint32(_fillRange(nullptr, 1));
}
quint64 generate64()
{
- quint32 buf[2];
- fillRange(buf);
- return buf[0] | (quint64(buf[1]) << 32);
+ return _fillRange(nullptr, sizeof(quint64) / sizeof(quint32));
}
double generateDouble()
@@ -139,16 +99,54 @@ public:
return bounded(highest - lowest) + lowest;
}
+ quint64 bounded(quint64 highest);
+
+ quint64 bounded(quint64 lowest, quint64 highest)
+ {
+ Q_ASSERT(highest > lowest);
+ return bounded(highest - lowest) + lowest;
+ }
+
+ qint64 bounded(qint64 highest)
+ {
+ Q_ASSERT(highest > 0);
+ return qint64(bounded(quint64(0), quint64(highest)));
+ }
+
+ qint64 bounded(qint64 lowest, qint64 highest)
+ {
+ return bounded(highest - lowest) + lowest;
+ }
+
+ // these functions here only to help with ambiguous overloads
+ qint64 bounded(int lowest, qint64 highest)
+ {
+ return bounded(qint64(lowest), qint64(highest));
+ }
+ qint64 bounded(qint64 lowest, int highest)
+ {
+ return bounded(qint64(lowest), qint64(highest));
+ }
+
+ quint64 bounded(unsigned lowest, quint64 highest)
+ {
+ return bounded(quint64(lowest), quint64(highest));
+ }
+ quint64 bounded(quint64 lowest, unsigned highest)
+ {
+ return bounded(quint64(lowest), quint64(highest));
+ }
+
template <typename UInt, IfValidUInt<UInt> = true>
void fillRange(UInt *buffer, qsizetype count)
{
- _fillRange(buffer, buffer + count);
+ _fillRange(buffer, count * sizeof(UInt) / sizeof(quint32));
}
template <typename UInt, size_t N, IfValidUInt<UInt> = true>
void fillRange(UInt (&buffer)[N])
{
- _fillRange(buffer, buffer + N);
+ _fillRange(buffer, N * sizeof(UInt) / sizeof(quint32));
}
// API like std::seed_seq
@@ -160,7 +158,7 @@ public:
void generate(quint32 *begin, quint32 *end)
{
- _fillRange(begin, end);
+ _fillRange(begin, end - begin);
}
// API like std:: random engines
@@ -169,8 +167,8 @@ public:
void seed(quint32 s = 1) { *this = { s }; }
void seed(std::seed_seq &sseq) noexcept { *this = { sseq }; }
Q_CORE_EXPORT void discard(unsigned long long z);
- static Q_DECL_CONSTEXPR result_type min() { return std::numeric_limits<result_type>::min(); }
- static Q_DECL_CONSTEXPR result_type max() { return std::numeric_limits<result_type>::max(); }
+ static constexpr result_type min() { return (std::numeric_limits<result_type>::min)(); }
+ static constexpr result_type max() { return (std::numeric_limits<result_type>::max)(); }
static inline Q_DECL_CONST_FUNCTION QRandomGenerator *system();
static inline Q_DECL_CONST_FUNCTION QRandomGenerator *global();
@@ -181,8 +179,12 @@ protected:
QRandomGenerator(System);
private:
- Q_CORE_EXPORT void _fillRange(void *buffer, void *bufferEnd);
+ Q_CORE_EXPORT quint64 _fillRange(void *buffer, qptrdiff count);
+ struct InitialRandomData {
+ quintptr data[16 / sizeof(quintptr)];
+ };
+ friend InitialRandomData qt_initial_random_value() noexcept;
friend class QRandomGenerator64;
struct SystemGenerator;
struct SystemAndGlobalGenerators;
@@ -191,19 +193,13 @@ private:
union Storage {
uint dummy;
-#ifdef Q_COMPILER_UNRESTRICTED_UNIONS
RandomEngine twister;
RandomEngine &engine() { return twister; }
const RandomEngine &engine() const { return twister; }
-#else
- std::aligned_storage<sizeof(RandomEngine), alignof(RandomEngine)>::type buffer;
- RandomEngine &engine() { return reinterpret_cast<RandomEngine &>(buffer); }
- const RandomEngine &engine() const { return reinterpret_cast<const RandomEngine &>(buffer); }
-#endif
static_assert(std::is_trivially_destructible<RandomEngine>::value,
"std::mersenne_twister not trivially destructible as expected");
- Q_DECL_CONSTEXPR Storage();
+ constexpr Storage();
};
uint type;
Storage storage;
@@ -245,14 +241,32 @@ public:
QRandomGenerator::discard(z * 2);
}
- static Q_DECL_CONSTEXPR result_type min() { return std::numeric_limits<result_type>::min(); }
- static Q_DECL_CONSTEXPR result_type max() { return std::numeric_limits<result_type>::max(); }
+ static constexpr result_type min() { return (std::numeric_limits<result_type>::min)(); }
+ static constexpr result_type max() { return (std::numeric_limits<result_type>::max)(); }
static Q_DECL_CONST_FUNCTION Q_CORE_EXPORT QRandomGenerator64 *system();
static Q_DECL_CONST_FUNCTION Q_CORE_EXPORT QRandomGenerator64 *global();
static Q_CORE_EXPORT QRandomGenerator64 securelySeeded();
#endif // Q_QDOC
};
+inline quint64 QRandomGenerator::bounded(quint64 highest)
+{
+ // Implement an algorithm similar to libc++'s uniform_int_distribution:
+ // loop around getting a random number, mask off any bits that "highest"
+ // will never need, then check if it's higher than "highest". The number of
+ // times the loop will run is unbounded but the probability of terminating
+ // is better than 1/2 on each iteration. Therefore, the average loop count
+ // should be less than 2.
+
+ const int width = qCountLeadingZeroBits(highest - 1);
+ const quint64 mask = (quint64(1) << (std::numeric_limits<quint64>::digits - width)) - 1;
+ quint64 v;
+ do {
+ v = generate64() & mask;
+ } while (v >= highest);
+ return v;
+}
+
inline QRandomGenerator *QRandomGenerator::system()
{
return QRandomGenerator64::system();
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-05 11:26:49 +0000