MinimalWindowsApi.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
//=====================================================================================================================
// Implementation of a minimal subset of the Windows API required for inline function definitions and platform-specific
// interfaces in Core. Use of this file allows avoiding including large platform headers in the public engine API.
//
// Win32 API functions are declared in the "Windows" namespace to avoid conflicts if the real Windows.h is included 
// later, but are mapped to the same imported symbols by the linker due to C-style linkage.
//=====================================================================================================================
 
#pragma once
 
#include "CoreTypes.h"
 
#ifdef __clang__
    #define MINIMAL_WINDOWS_API CORE_API
#else
    #define MINIMAL_WINDOWS_API extern "C" __declspec(dllimport)
#endif
 
// The 10.0.18362.0 SDK introduces an error if the packing isn't the default for the platform.
PRAGMA_PUSH_PLATFORM_DEFAULT_PACKING
 
// Undefine Windows types that we're going to redefine. This should be done by HideWindowsPlatformTypes.h after including any system headers, 
// but it's less friction to just undefine them here.
#pragma push_macro("TRUE")
#pragma push_macro("FALSE")
#undef TRUE
#undef FALSE
 
// Use strongly typed handles
#ifndef STRICT
#define STRICT
#endif
 
// With STRICT enabled, handles are implemented as opaque struct pointers. We can prototype these structs here and 
// typedef them under the Windows namespace below. Since typedefs are only aliases rather than types in their own 
// right, this allows using handles from the Windows:: namespace interchangably with their native definition.
struct HINSTANCE__;
struct HWND__;
struct HKEY__;
struct HDC__;
struct HICON__;
struct _RTL_SRWLOCK;
 
// Other types
struct tagPROCESSENTRY32W;
struct _EXCEPTION_POINTERS;
struct _OVERLAPPED;
struct _RTL_CRITICAL_SECTION;
union _LARGE_INTEGER;
 
// Global constants
#define WINDOWS_MAX_PATH 260
#define WINDOWS_PF_COMPARE_EXCHANGE128  14
 
// Standard calling convention for Win32 functions
#define WINAPI __stdcall
 
// Minimal subset of the Windows API required for interfaces and inline functions
namespace Windows
{
    // Typedefs for basic Windows types
    typedef int32 BOOL;
    typedef unsigned char BYTE;
    typedef BYTE  BOOLEAN;
    typedef unsigned long DWORD;
    typedef DWORD* LPDWORD;
    typedef long LONG;
    typedef long* LPLONG;
    typedef int64 LONGLONG;
    typedef LONGLONG* LPLONGLONG;
    typedef void* LPVOID;
    typedef const void* LPCVOID;
    typedef const wchar_t* LPCTSTR;
 
    // Typedefs for standard handles
    typedef void* HANDLE;
    typedef HINSTANCE__* HINSTANCE;
    typedef HINSTANCE HMODULE;
    typedef HWND__* HWND;
    typedef HKEY__* HKEY;
    typedef HDC__* HDC;
    typedef HICON__* HICON;
    typedef HICON__* HCURSOR;
 
    // Other typedefs
    typedef tagPROCESSENTRY32W PROCESSENTRY32;
    typedef _EXCEPTION_POINTERS* LPEXCEPTION_POINTERS;
    typedef _RTL_CRITICAL_SECTION* LPCRITICAL_SECTION;
    typedef _OVERLAPPED* LPOVERLAPPED;
    typedef _LARGE_INTEGER* LPLARGE_INTEGER;
 
    typedef _RTL_SRWLOCK RTL_SRWLOCK, *PRTL_SRWLOCK;
    typedef RTL_SRWLOCK *PSRWLOCK;
 
    typedef void (*PFLS_CALLBACK_FUNCTION) (void* lpFlsData);
 
 
    // Opaque SRWLOCK structure
    struct SRWLOCK
    {
        void* Ptr;
    };
 
    // Constants
    inline constexpr BOOL TRUE = 1;
    inline constexpr BOOL FALSE = 0;
 
    // Modules
    MINIMAL_WINDOWS_API HMODULE WINAPI LoadLibraryW(LPCTSTR lpFileName);
    MINIMAL_WINDOWS_API BOOL WINAPI FreeLibrary(HMODULE hModule);
 
    // Critical sections
    MINIMAL_WINDOWS_API void WINAPI InitializeCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
    MINIMAL_WINDOWS_API BOOL WINAPI InitializeCriticalSectionAndSpinCount(LPCRITICAL_SECTION lpCriticalSection, DWORD dwSpinCount);
    MINIMAL_WINDOWS_API DWORD WINAPI SetCriticalSectionSpinCount(LPCRITICAL_SECTION lpCriticalSection, DWORD dwSpinCount);
    MINIMAL_WINDOWS_API BOOL WINAPI TryEnterCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
    MINIMAL_WINDOWS_API void WINAPI EnterCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
    MINIMAL_WINDOWS_API void WINAPI LeaveCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
    MINIMAL_WINDOWS_API void WINAPI DeleteCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
 
    MINIMAL_WINDOWS_API void WINAPI InitializeSRWLock(PSRWLOCK SRWLock);
    MINIMAL_WINDOWS_API void WINAPI AcquireSRWLockShared(PSRWLOCK SRWLock);
    MINIMAL_WINDOWS_API void WINAPI ReleaseSRWLockShared(PSRWLOCK SRWLock);
    MINIMAL_WINDOWS_API void WINAPI AcquireSRWLockExclusive(PSRWLOCK SRWLock);
    MINIMAL_WINDOWS_API void WINAPI ReleaseSRWLockExclusive(PSRWLOCK SRWLock);
    MINIMAL_WINDOWS_API BOOLEAN WINAPI TryAcquireSRWLockExclusive(PSRWLOCK SRWLock);
    MINIMAL_WINDOWS_API BOOLEAN WINAPI TryAcquireSRWLockShared(PSRWLOCK SRWLock);
 
    UE_FORCEINLINE_HINT void WINAPI InitializeSRWLock(SRWLOCK* SRWLock)
    {
        InitializeSRWLock((PSRWLOCK)SRWLock);
    }
 
    UE_FORCEINLINE_HINT BOOLEAN WINAPI TryAcquireSRWLockExclusive(SRWLOCK* SRWLock)
    {
        return TryAcquireSRWLockExclusive((PSRWLOCK)SRWLock);
    }
 
    UE_FORCEINLINE_HINT BOOLEAN WINAPI TryAcquireSRWLockShared(SRWLOCK* SRWLock)
    {
        return TryAcquireSRWLockShared((PSRWLOCK)SRWLock);
    }
    
    UE_FORCEINLINE_HINT void WINAPI AcquireSRWLockShared(SRWLOCK* SRWLock)
    {
        AcquireSRWLockShared((PSRWLOCK)SRWLock);
    }
 
    UE_FORCEINLINE_HINT void WINAPI ReleaseSRWLockShared(SRWLOCK* SRWLock)
    {
        ReleaseSRWLockShared((PSRWLOCK)SRWLock);
    }
 
    UE_FORCEINLINE_HINT void WINAPI AcquireSRWLockExclusive(SRWLOCK* SRWLock)
    {
        AcquireSRWLockExclusive((PSRWLOCK)SRWLock);
    }
 
    UE_FORCEINLINE_HINT void WINAPI ReleaseSRWLockExclusive(SRWLOCK* SRWLock)
    {
        ReleaseSRWLockExclusive((PSRWLOCK)SRWLock);
    }
 
    // I/O
    MINIMAL_WINDOWS_API BOOL WINAPI ConnectNamedPipe(HANDLE hNamedPipe, LPOVERLAPPED lpOverlapped);
    MINIMAL_WINDOWS_API BOOL WINAPI GetOverlappedResult(HANDLE hFile, LPOVERLAPPED lpOverlapped, LPDWORD lpNumberOfBytesTransferred, BOOL bWait);
    MINIMAL_WINDOWS_API BOOL WINAPI WriteFile(HANDLE hFile, LPCVOID lpBuffer, DWORD nNumberOfBytesToWrite, LPDWORD lpNumberOfBytesWritten, LPOVERLAPPED lpOverlapped);
    MINIMAL_WINDOWS_API BOOL WINAPI ReadFile(HANDLE hFile, LPVOID lpBuffer, DWORD nNumberOfBytesToRead, LPDWORD lpNumberOfBytesRead, LPOVERLAPPED lpOverlapped);
 
    // Timing
    MINIMAL_WINDOWS_API BOOL WINAPI QueryPerformanceCounter(LPLARGE_INTEGER Cycles);
 
    // Thread-local storage functions
    MINIMAL_WINDOWS_API DWORD WINAPI GetCurrentThreadId();
    MINIMAL_WINDOWS_API DWORD WINAPI TlsAlloc();
    MINIMAL_WINDOWS_API LPVOID WINAPI TlsGetValue(DWORD dwTlsIndex);
    MINIMAL_WINDOWS_API BOOL WINAPI TlsSetValue(DWORD dwTlsIndex, LPVOID lpTlsValue);
    MINIMAL_WINDOWS_API BOOL WINAPI TlsFree(DWORD dwTlsIndex);
 
    // Fiber-local storage functions
    MINIMAL_WINDOWS_API DWORD WINAPI FlsAlloc(PFLS_CALLBACK_FUNCTION lpCallback);
    MINIMAL_WINDOWS_API LPVOID WINAPI FlsGetValue(DWORD dwFlsIndex);
    MINIMAL_WINDOWS_API BOOL WINAPI FlsSetValue(DWORD dwFlsIndex, LPVOID lpFlsValue);
    MINIMAL_WINDOWS_API BOOL WINAPI FlsFree(DWORD dwTlsIndex);
 
    // System
    MINIMAL_WINDOWS_API BOOL WINAPI IsProcessorFeaturePresent(DWORD ProcessorFeature);
 
    // For structures which are opaque
    struct CRITICAL_SECTION { void* Opaque1[1]; long Opaque2[2]; void* Opaque3[3]; };
    struct OVERLAPPED { void *Opaque[3]; unsigned long Opaque2[2]; };
    union LARGE_INTEGER { struct { DWORD LowPart; LONG HighPart; }; LONGLONG QuadPart; };
 
    UE_FORCEINLINE_HINT BOOL WINAPI ConnectNamedPipe(HANDLE hNamedPipe, OVERLAPPED* lpOverlapped)
    {
        return ConnectNamedPipe(hNamedPipe, (LPOVERLAPPED)lpOverlapped);
    }
 
    UE_FORCEINLINE_HINT BOOL WINAPI GetOverlappedResult(HANDLE hFile, OVERLAPPED* lpOverlapped, LPDWORD lpNumberOfBytesTransferred, BOOL bWait)
    {
        return GetOverlappedResult(hFile, (LPOVERLAPPED)lpOverlapped, lpNumberOfBytesTransferred, bWait);
    }
 
    UE_FORCEINLINE_HINT BOOL WINAPI WriteFile(HANDLE hFile, LPCVOID lpBuffer, DWORD nNumberOfBytesToWrite, LPDWORD lpNumberOfBytesWritten, OVERLAPPED* lpOverlapped)
    {
        return WriteFile(hFile, lpBuffer, nNumberOfBytesToWrite, lpNumberOfBytesWritten, (LPOVERLAPPED)lpOverlapped);
    }
 
    UE_FORCEINLINE_HINT BOOL WINAPI ReadFile(HANDLE hFile, LPVOID lpBuffer, DWORD nNumberOfBytesToRead, LPDWORD lpNumberOfBytesRead, OVERLAPPED* lpOverlapped)
    {
        return ReadFile(hFile, lpBuffer, nNumberOfBytesToRead, lpNumberOfBytesRead, (LPOVERLAPPED)lpOverlapped);
    }
 
    UE_FORCEINLINE_HINT void WINAPI InitializeCriticalSection(CRITICAL_SECTION* lpCriticalSection)
    {
        InitializeCriticalSection((LPCRITICAL_SECTION)lpCriticalSection);
    }
 
    UE_FORCEINLINE_HINT BOOL WINAPI InitializeCriticalSectionAndSpinCount(CRITICAL_SECTION* lpCriticalSection, DWORD dwSpinCount)
    {
        return InitializeCriticalSectionAndSpinCount((LPCRITICAL_SECTION)lpCriticalSection, dwSpinCount);
    }
 
    UE_FORCEINLINE_HINT DWORD WINAPI SetCriticalSectionSpinCount(CRITICAL_SECTION* lpCriticalSection, DWORD dwSpinCount)
    {
        return SetCriticalSectionSpinCount((LPCRITICAL_SECTION)lpCriticalSection, dwSpinCount);
    }
 
    UE_FORCEINLINE_HINT BOOL WINAPI TryEnterCriticalSection(CRITICAL_SECTION* lpCriticalSection)
    {
        return TryEnterCriticalSection((LPCRITICAL_SECTION)lpCriticalSection);
    }
 
    UE_FORCEINLINE_HINT void WINAPI EnterCriticalSection(CRITICAL_SECTION* lpCriticalSection)
    {
        EnterCriticalSection((LPCRITICAL_SECTION)lpCriticalSection);
    }
 
    UE_FORCEINLINE_HINT void WINAPI LeaveCriticalSection(CRITICAL_SECTION* lpCriticalSection)
    {
        LeaveCriticalSection((LPCRITICAL_SECTION)lpCriticalSection);
    }
 
    UE_FORCEINLINE_HINT void WINAPI DeleteCriticalSection(CRITICAL_SECTION* lpCriticalSection)
    {
        DeleteCriticalSection((LPCRITICAL_SECTION)lpCriticalSection);
    }
 
    UE_FORCEINLINE_HINT BOOL WINAPI QueryPerformanceCounter(LARGE_INTEGER* Cycles)
    {
        return QueryPerformanceCounter((LPLARGE_INTEGER)Cycles);
    }
}
 
// Restore the definitions for TRUE and FALSE
#pragma pop_macro("FALSE")
#pragma pop_macro("TRUE")
 
// Restore the packing setting
PRAGMA_POP_PLATFORM_DEFAULT_PACKING