misc.h

/*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)

  Stockfish is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Stockfish is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef MISC_H_INCLUDED
#define MISC_H_INCLUDED

#include <cassert>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <iosfwd>
#include <string>

#define stringify2(x) #x
#define stringify(x) stringify2(x)

namespace Stockfish {

std::string engine_info(bool to_uci = false);
std::string compiler_info();

// Preloads the given address in L1/L2 cache. This is a non-blocking
// function that doesn't stall the CPU waiting for data to be loaded from memory,
// which can be quite slow.
void prefetch(void* addr);

void  start_logger(const std::string& fname);
void* std_aligned_alloc(size_t alignment, size_t size);
void  std_aligned_free(void* ptr);
// memory aligned by page size, min alignment: 4096 bytes
void* aligned_large_pages_alloc(size_t size);
// nop if mem == nullptr
void aligned_large_pages_free(void* mem);

void dbg_hit_on(bool cond, int slot = 0);
void dbg_mean_of(int64_t value, int slot = 0);
void dbg_stdev_of(int64_t value, int slot = 0);
void dbg_correl_of(int64_t value1, int64_t value2, int slot = 0);
void dbg_print();

using TimePoint = std::chrono::milliseconds::rep;  // A value in milliseconds
static_assert(sizeof(TimePoint) == sizeof(int64_t), "TimePoint should be 64 bits");
inline TimePoint now() {
    return std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now().time_since_epoch())
      .count();
}


enum SyncCout {
    IO_LOCK,
    IO_UNLOCK
};
std::ostream& operator<<(std::ostream&, SyncCout);

#define sync_cout std::cout << IO_LOCK
#define sync_endl std::endl << IO_UNLOCK


// Get the first aligned element of an array.
// ptr must point to an array of size at least `sizeof(T) * N + alignment` bytes,
// where N is the number of elements in the array.
template<uintptr_t Alignment, typename T>
T* align_ptr_up(T* ptr) {
    static_assert(alignof(T) < Alignment);

    const uintptr_t ptrint = reinterpret_cast<uintptr_t>(reinterpret_cast<char*>(ptr));
    return reinterpret_cast<T*>(
      reinterpret_cast<char*>((ptrint + (Alignment - 1)) / Alignment * Alignment));
}


// True if and only if the binary is compiled on a little-endian machine
static inline const union {
    uint32_t i;
    char     c[4];
} Le                                    = {0x01020304};
static inline const bool IsLittleEndian = (Le.c[0] == 4);


template<typename T, std::size_t MaxSize>
class ValueList {

   public:
    std::size_t size() const { return size_; }
    void        push_back(const T& value) { values_[size_++] = value; }
    const T*    begin() const { return values_; }
    const T*    end() const { return values_ + size_; }
    const T&    operator[](int index) const { return values_[index]; }

   private:
    T           values_[MaxSize];
    std::size_t size_ = 0;
};


// xorshift64star Pseudo-Random Number Generator
// This class is based on original code written and dedicated
// to the public domain by Sebastiano Vigna (2014).
// It has the following characteristics:
//
//  -  Outputs 64-bit numbers
//  -  Passes Dieharder and SmallCrush test batteries
//  -  Does not require warm-up, no zeroland to escape
//  -  Internal state is a single 64-bit integer
//  -  Period is 2^64 - 1
//  -  Speed: 1.60 ns/call (Core i7 @3.40GHz)
//
// For further analysis see
//   <http://vigna.di.unimi.it/ftp/papers/xorshift.pdf>

class PRNG {

    uint64_t s;

    uint64_t rand64() {

        s ^= s >> 12, s ^= s << 25, s ^= s >> 27;
        return s * 2685821657736338717LL;
    }

   public:
    PRNG(uint64_t seed) :
        s(seed) {
        assert(seed);
    }

    template<typename T>
    T rand() {
        return T(rand64());
    }

    // Special generator used to fast init magic numbers.
    // Output values only have 1/8th of their bits set on average.
    template<typename T>
    T sparse_rand() {
        return T(rand64() & rand64() & rand64());
    }
};

inline uint64_t mul_hi64(uint64_t a, uint64_t b) {
#if defined(__GNUC__) && defined(IS_64BIT)
    __extension__ using uint128 = unsigned __int128;
    return (uint128(a) * uint128(b)) >> 64;
#else
    uint64_t aL = uint32_t(a), aH = a >> 32;
    uint64_t bL = uint32_t(b), bH = b >> 32;
    uint64_t c1 = (aL * bL) >> 32;
    uint64_t c2 = aH * bL + c1;
    uint64_t c3 = aL * bH + uint32_t(c2);
    return aH * bH + (c2 >> 32) + (c3 >> 32);
#endif
}

// Under Windows it is not possible for a process to run on more than one
// logical processor group. This usually means being limited to using max 64
// cores. To overcome this, some special platform-specific API should be
// called to set group affinity for each thread. Original code from Texel by
// Peter Österlund.
namespace WinProcGroup {
void bindThisThread(size_t idx);
}

namespace CommandLine {
void init(int argc, char* argv[]);

extern std::string binaryDirectory;   // path of the executable directory
extern std::string workingDirectory;  // path of the working directory
}

}  // namespace Stockfish

#endif  // #ifndef MISC_H_INCLUDED