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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Platform.h>
#include <AK/StdLibExtras.h>
#include <AK/Types.h>
#if defined(AK_OS_SERENITY) || defined(AK_OS_ANDROID)
# include <stdlib.h>
#endif
#if defined(__unix__)
# include <unistd.h>
#endif
#if defined(AK_OS_MACOS)
# include <sys/random.h>
#endif
#if defined(AK_OS_WINDOWS)
# include <stdlib.h>
#endif
namespace AK {
inline void fill_with_random([[maybe_unused]] void* buffer, [[maybe_unused]] size_t length)
{
#if defined(AK_OS_SERENITY) || defined(AK_OS_ANDROID)
arc4random_buf(buffer, length);
#elif defined(OSS_FUZZ)
#elif defined(__unix__) or defined(AK_OS_MACOS)
[[maybe_unused]] int rc = getentropy(buffer, length);
#else
char* char_buffer = static_cast<char*>(buffer);
for (size_t i = 0; i < length; i++) {
char_buffer[i] = rand();
}
#endif
}
template<typename T>
inline T get_random()
{
T t;
fill_with_random(&t, sizeof(T));
return t;
}
u32 get_random_uniform(u32 max_bounds);
template<typename Collection>
inline void shuffle(Collection& collection)
{
// Fisher-Yates shuffle
for (size_t i = collection.size() - 1; i >= 1; --i) {
size_t j = get_random_uniform(i + 1);
AK::swap(collection[i], collection[j]);
}
}
// shuffle() implementation for NonnullPtrVector, since its operator[] returns a reference to the pointed-at value
// instead of the pointer itself.
template<typename Collection>
requires(requires(Collection collection) { collection.ptr_at(0); })
inline void shuffle(Collection& collection)
{
// Fisher-Yates shuffle
for (size_t i = collection.size() - 1; i >= 1; --i) {
size_t j = get_random_uniform(i + 1);
AK::swap(collection.ptr_at(i), collection.ptr_at(j));
}
}
}
#if USING_AK_GLOBALLY
using AK::fill_with_random;
using AK::get_random;
using AK::get_random_uniform;
using AK::shuffle;
#endif
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