/*
 * Copyright 2013 Haiku, Inc. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *              Paweł Dziepak, pdziepak@quarnos.org
 */
#ifndef KERNEL_UTIL_RANDOM_H
#define KERNEL_UTIL_RANDOM_H


#include <smp.h>
#include <SupportDefs.h>


#define MAX_FAST_RANDOM_VALUE           0x7fff
#define MAX_RANDOM_VALUE                        0x7fffffffu
#define MAX_SECURE_RANDOM_VALUE         0xffffffffu

static const int        kFastRandomShift                = 15;
static const int        kRandomShift                    = 31;
static const int        kSecureRandomShift              = 32;

#ifdef __cplusplus
extern "C" {
#endif

unsigned int    fast_random_value(void);
unsigned int    random_value(void);
unsigned int    secure_random_value(void);

#ifdef __cplusplus
}
#endif


#ifdef __cplusplus

template<typename T>
T
fast_get_random()
{
        size_t shift = 0;
        T random = 0;
        while (shift < sizeof(T) * 8) {
                random |= (T)fast_random_value() << shift;
                shift += kFastRandomShift;
        }

        return random;
}


template<typename T>
T
get_random()
{
        size_t shift = 0;
        T random = 0;
        while (shift < sizeof(T) * 8) {
                random |= (T)random_value() << shift;
                shift += kRandomShift;
        }

        return random;
}


template<typename T>
T
secure_get_random()
{
        size_t shift = 0;
        T random = 0;
        while (shift < sizeof(T) * 8) {
                random |= (T)secure_random_value() << shift;
                shift += kSecureRandomShift;
        }

        return random;
}


#endif  // __cplusplus

#endif  // KERNEL_UTIL_RANDOM_H