// [AsmJit]
// Complete x86/x64 JIT and Remote Assembler for C++.
//
// [License]
// Zlib - See LICENSE.md file in the package.

// [Guard]
#ifndef _ASMJIT_BASE_OSUTILS_H
#define _ASMJIT_BASE_OSUTILS_H

// [Dependencies]
#include "../base/globals.h"

// [Api-Begin]
#include "../asmjit_apibegin.h"

namespace asmjit {

//! \addtogroup asmjit_base
//! \{

// ============================================================================
// [asmjit::VMemInfo]
// ============================================================================

//! Information about OS virtual memory.
struct VMemInfo {
#if ASMJIT_OS_WINDOWS
  HANDLE hCurrentProcess;                //!< Handle of the current process (Windows).
#endif // ASMJIT_OS_WINDOWS
  size_t pageSize;                       //!< Virtual memory page size.
  size_t pageGranularity;                //!< Virtual memory page granularity.
};

// ============================================================================
// [asmjit::OSUtils]
// ============================================================================

//! OS utilities.
//!
//! Virtual Memory
//! --------------
//!
//! Provides functions to allocate and release virtual memory that is required
//! to execute dynamically generated code. If both processor and host OS support
//! data-execution-prevention (DEP) then the only way to run machine code is to
//! allocate virtual memory that has `OSUtils::kVMExecutable` flag enabled. All
//! functions provides by OSUtils use internally platform specific API.
//!
//! Benchmarking
//! ------------
//!
//! OSUtils also provide a function `getTickCount()` that can be used for
//! benchmarking purposes. It's similar to Windows-only `GetTickCount()`, but
//! it's cross-platform and tries to be the most reliable platform specific
//! calls to make the result usable.
struct OSUtils {
  // --------------------------------------------------------------------------
  // [Virtual Memory]
  // --------------------------------------------------------------------------

  //! Virtual memory flags.
  ASMJIT_ENUM(VMFlags) {
    kVMWritable   = 0x00000001U,         //!< Virtual memory is writable.
    kVMExecutable = 0x00000002U          //!< Virtual memory is executable.
  };

  ASMJIT_API static VMemInfo getVirtualMemoryInfo() noexcept;

  //! Allocate virtual memory.
  ASMJIT_API static void* allocVirtualMemory(size_t size, size_t* allocated, uint32_t flags) noexcept;
  //! Release virtual memory previously allocated by \ref allocVirtualMemory().
  ASMJIT_API static Error releaseVirtualMemory(void* p, size_t size) noexcept;

#if ASMJIT_OS_WINDOWS
  //! Allocate virtual memory of `hProcess` (Windows).
  ASMJIT_API static void* allocProcessMemory(HANDLE hProcess, size_t size, size_t* allocated, uint32_t flags) noexcept;

  //! Release virtual memory of `hProcess` (Windows).
  ASMJIT_API static Error releaseProcessMemory(HANDLE hProcess, void* p, size_t size) noexcept;
#endif // ASMJIT_OS_WINDOWS

  // --------------------------------------------------------------------------
  // [GetTickCount]
  // --------------------------------------------------------------------------

  //! Get the current CPU tick count, used for benchmarking (1ms resolution).
  ASMJIT_API static uint32_t getTickCount() noexcept;
};

// ============================================================================
// [asmjit::Lock]
// ============================================================================

//! \internal
//!
//! Lock.
struct Lock {
  ASMJIT_NONCOPYABLE(Lock)

  // --------------------------------------------------------------------------
  // [Windows]
  // --------------------------------------------------------------------------

#if ASMJIT_OS_WINDOWS
  typedef CRITICAL_SECTION Handle;

  //! Create a new `Lock` instance.
  ASMJIT_INLINE Lock() noexcept { InitializeCriticalSection(&_handle); }
  //! Destroy the `Lock` instance.
  ASMJIT_INLINE ~Lock() noexcept { DeleteCriticalSection(&_handle); }

  //! Lock.
  ASMJIT_INLINE void lock() noexcept { EnterCriticalSection(&_handle); }
  //! Unlock.
  ASMJIT_INLINE void unlock() noexcept { LeaveCriticalSection(&_handle); }
#endif // ASMJIT_OS_WINDOWS

  // --------------------------------------------------------------------------
  // [Posix]
  // --------------------------------------------------------------------------

#if ASMJIT_OS_POSIX
  typedef pthread_mutex_t Handle;

  //! Create a new `Lock` instance.
  ASMJIT_INLINE Lock() noexcept { pthread_mutex_init(&_handle, nullptr); }
  //! Destroy the `Lock` instance.
  ASMJIT_INLINE ~Lock() noexcept { pthread_mutex_destroy(&_handle); }

  //! Lock.
  ASMJIT_INLINE void lock() noexcept { pthread_mutex_lock(&_handle); }
  //! Unlock.
  ASMJIT_INLINE void unlock() noexcept { pthread_mutex_unlock(&_handle); }
#endif // ASMJIT_OS_POSIX

  // --------------------------------------------------------------------------
  // [Members]
  // --------------------------------------------------------------------------

  //! Native handle.
  Handle _handle;
};

// ============================================================================
// [asmjit::AutoLock]
// ============================================================================

//! \internal
//!
//! Scoped lock.
struct AutoLock {
  ASMJIT_NONCOPYABLE(AutoLock)

  // --------------------------------------------------------------------------
  // [Construction / Destruction]
  // --------------------------------------------------------------------------

  ASMJIT_INLINE AutoLock(Lock& target) noexcept : _target(target) { _target.lock(); }
  ASMJIT_INLINE ~AutoLock() noexcept { _target.unlock(); }

  // --------------------------------------------------------------------------
  // [Members]
  // --------------------------------------------------------------------------

  //! Reference to the `Lock`.
  Lock& _target;
};

//! \}

} // asmjit namespace

// [Api-End]
#include "../asmjit_apiend.h"

// [Guard]
#endif // _ASMJIT_BASE_OSUTILS_H