/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

// -*- c++ -*-

/* Random generators. Implemented here for speed and to make
 * sequences reproducible.
 */

#pragma once

#include <random>
#include <stdint.h>


namespace faiss {

/**************************************************
 * Random data generation functions
 **************************************************/

/// random generator that can be used in multithreaded contexts
struct RandomGenerator {

    std::mt19937 mt;

    /// random positive integer
    int rand_int ();

    /// random int64_t
    int64_t rand_int64 ();

    /// generate random integer between 0 and max-1
    int rand_int (int max);

    /// between 0 and 1
    float rand_float ();

    double rand_double ();

    explicit RandomGenerator (int64_t seed = 1234);
};

/* Generate an array of uniform random floats / multi-threaded implementation */
void float_rand (float * x, size_t n, int64_t seed);
void float_randn (float * x, size_t n, int64_t seed);
void int64_rand (int64_t * x, size_t n, int64_t seed);
void byte_rand (uint8_t * x, size_t n, int64_t seed);
// max is actually the maximum value + 1
void int64_rand_max (int64_t * x, size_t n, uint64_t max, int64_t seed);

/* random permutation */
void rand_perm (int * perm, size_t n, int64_t seed);


} // namespace faiss