PeekMessageA

// USER32.dll  (ANSI / -A)
#include <windows.h>

BOOL PeekMessageA(
    MSG* lpMsg,
    HWND hWnd,   // optional
    DWORD wMsgFilterMin,
    DWORD wMsgFilterMax,
    PEEK_MESSAGE_REMOVE_TYPE wRemoveMsg
);

<DllImport("USER32.dll", CharSet:=CharSet.Ansi, ExactSpelling:=True)>
Public Shared Function PeekMessageA(
    lpMsg As IntPtr,   ' MSG* out
    hWnd As IntPtr,   ' HWND optional
    wMsgFilterMin As UInteger,   ' DWORD
    wMsgFilterMax As UInteger,   ' DWORD
    wRemoveMsg As UInteger   ' PEEK_MESSAGE_REMOVE_TYPE
) As <MarshalAs(UnmanagedType.Bool)> Boolean
End Function

' lpMsg : MSG* out
' hWnd : HWND optional
' wMsgFilterMin : DWORD
' wMsgFilterMax : DWORD
' wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE
Declare PtrSafe Function PeekMessageA Lib "user32" ( _
    ByVal lpMsg As LongPtr, _
    ByVal hWnd As LongPtr, _
    ByVal wMsgFilterMin As Long, _
    ByVal wMsgFilterMax As Long, _
    ByVal wRemoveMsg As Long) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

PeekMessageA = ctypes.windll.user32.PeekMessageA
PeekMessageA.restype = wintypes.BOOL
PeekMessageA.argtypes = [
    ctypes.c_void_p,  # lpMsg : MSG* out
    wintypes.HANDLE,  # hWnd : HWND optional
    wintypes.DWORD,  # wMsgFilterMin : DWORD
    wintypes.DWORD,  # wMsgFilterMax : DWORD
    wintypes.DWORD,  # wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
PeekMessageA = Fiddle::Function.new(
  lib['PeekMessageA'],
  [
    Fiddle::TYPE_VOIDP,  # lpMsg : MSG* out
    Fiddle::TYPE_VOIDP,  # hWnd : HWND optional
    -Fiddle::TYPE_INT,  # wMsgFilterMin : DWORD
    -Fiddle::TYPE_INT,  # wMsgFilterMax : DWORD
    -Fiddle::TYPE_INT,  # wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE
  ],
  Fiddle::TYPE_INT)

#[link(name = "user32")]
extern "system" {
    fn PeekMessageA(
        lpMsg: *mut MSG,  // MSG* out
        hWnd: *mut core::ffi::c_void,  // HWND optional
        wMsgFilterMin: u32,  // DWORD
        wMsgFilterMax: u32,  // DWORD
        wRemoveMsg: u32  // PEEK_MESSAGE_REMOVE_TYPE
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("USER32.dll", CharSet = CharSet.Ansi)]
public static extern bool PeekMessageA(IntPtr lpMsg, IntPtr hWnd, uint wMsgFilterMin, uint wMsgFilterMax, uint wRemoveMsg);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_PeekMessageA' -Namespace Win32 -PassThru
# $api::PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg)

#uselib "USER32.dll"
#func global PeekMessageA "PeekMessageA" sptr, sptr, sptr, sptr, sptr
; PeekMessageA varptr(lpMsg), hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg   ; 戻り値は stat
; lpMsg : MSG* out -> "sptr"
; hWnd : HWND optional -> "sptr"
; wMsgFilterMin : DWORD -> "sptr"
; wMsgFilterMax : DWORD -> "sptr"
; wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> "sptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procPeekMessageA = user32.NewProc("PeekMessageA")
)

// lpMsg (MSG* out), hWnd (HWND optional), wMsgFilterMin (DWORD), wMsgFilterMax (DWORD), wRemoveMsg (PEEK_MESSAGE_REMOVE_TYPE)
r1, _, err := procPeekMessageA.Call(
	uintptr(lpMsg),
	uintptr(hWnd),
	uintptr(wMsgFilterMin),
	uintptr(wMsgFilterMax),
	uintptr(wRemoveMsg),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function PeekMessageA(
  lpMsg: Pointer;   // MSG* out
  hWnd: THandle;   // HWND optional
  wMsgFilterMin: DWORD;   // DWORD
  wMsgFilterMax: DWORD;   // DWORD
  wRemoveMsg: DWORD   // PEEK_MESSAGE_REMOVE_TYPE
): BOOL; stdcall;
  external 'USER32.dll' name 'PeekMessageA';

result := DllCall("USER32\PeekMessageA"
    , "Ptr", lpMsg   ; MSG* out
    , "Ptr", hWnd   ; HWND optional
    , "UInt", wMsgFilterMin   ; DWORD
    , "UInt", wMsgFilterMax   ; DWORD
    , "UInt", wRemoveMsg   ; PEEK_MESSAGE_REMOVE_TYPE
    , "Int")   ; return: BOOL

●PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg) = DLL("USER32.dll", "bool PeekMessageA(void*, void*, dword, dword, dword)")
# 呼び出し: PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg)
# lpMsg : MSG* out -> "void*"
# hWnd : HWND optional -> "void*"
# wMsgFilterMin : DWORD -> "dword"
# wMsgFilterMax : DWORD -> "dword"
# wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> "dword"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。

const std = @import("std");

extern "user32" fn PeekMessageA(
    lpMsg: [*c]MSG, // MSG* out
    hWnd: ?*anyopaque, // HWND optional
    wMsgFilterMin: u32, // DWORD
    wMsgFilterMax: u32, // DWORD
    wRemoveMsg: u32 // PEEK_MESSAGE_REMOVE_TYPE
) callconv(std.os.windows.WINAPI) i32;

proc PeekMessageA(
    lpMsg: ptr MSG,  # MSG* out
    hWnd: pointer,  # HWND optional
    wMsgFilterMin: uint32,  # DWORD
    wMsgFilterMax: uint32,  # DWORD
    wRemoveMsg: uint32  # PEEK_MESSAGE_REMOVE_TYPE
): int32 {.importc: "PeekMessageA", stdcall, dynlib: "USER32.dll".}

pragma(lib, "user32");
extern(Windows)
int PeekMessageA(
    MSG* lpMsg,   // MSG* out
    void* hWnd,   // HWND optional
    uint wMsgFilterMin,   // DWORD
    uint wMsgFilterMax,   // DWORD
    uint wRemoveMsg   // PEEK_MESSAGE_REMOVE_TYPE
);

ccall((:PeekMessageA, "USER32.dll"), stdcall, Int32,
      (Ptr{MSG}, Ptr{Cvoid}, UInt32, UInt32, UInt32),
      lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg)
# lpMsg : MSG* out -> Ptr{MSG}
# hWnd : HWND optional -> Ptr{Cvoid}
# wMsgFilterMin : DWORD -> UInt32
# wMsgFilterMax : DWORD -> UInt32
# wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> UInt32
# stdcall は 32bit のみ意味を持つ(x64 では無視)。

local ffi = require("ffi")
ffi.cdef[[
int32_t PeekMessageA(
    void* lpMsg,
    void* hWnd,
    uint32_t wMsgFilterMin,
    uint32_t wMsgFilterMax,
    uint32_t wRemoveMsg);
]]
local user32 = ffi.load("user32")
-- user32.PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg)
-- lpMsg : MSG* out
-- hWnd : HWND optional
-- wMsgFilterMin : DWORD
-- wMsgFilterMax : DWORD
-- wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE
-- 構造体/GUIDへのポインタは cdef が通るよう void* で表記(実型は各引数コメント参照)。値渡し構造体・enum は対応する typedef を cdef に追加すること。

const koffi = require('koffi');
const lib = koffi.load('USER32.dll');
const PeekMessageA = lib.func('__stdcall', 'PeekMessageA', 'int32_t', ['void *', 'void *', 'uint32_t', 'uint32_t', 'uint32_t']);
// PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg)
// lpMsg : MSG* out -> 'void *'
// hWnd : HWND optional -> 'void *'
// wMsgFilterMin : DWORD -> 'uint32_t'
// wMsgFilterMax : DWORD -> 'uint32_t'
// wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> 'uint32_t'
// 出力ポインタは koffi.out(...) で包む。構造体は koffi.struct で定義。

const lib = Deno.dlopen("USER32.dll", {
  PeekMessageA: { parameters: ["pointer", "pointer", "u32", "u32", "u32"], result: "i32" },
});
// lib.symbols.PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg)
// lpMsg : MSG* out -> "pointer"
// hWnd : HWND optional -> "pointer"
// wMsgFilterMin : DWORD -> "u32"
// wMsgFilterMax : DWORD -> "u32"
// wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> "u32"
// 文字列は "buffer"。ANSI(-A) は new TextEncoder() で UTF-8/ANSI バイト列(末尾に \x00)を渡す。
// 値渡し構造体は { struct: [ ...field types... ] } を使用。

<?php
$ffi = FFI::cdef(<<<C
int32_t PeekMessageA(
    void* lpMsg,
    void* hWnd,
    uint32_t wMsgFilterMin,
    uint32_t wMsgFilterMax,
    uint32_t wRemoveMsg);
C, "USER32.dll");
// $ffi->PeekMessageA(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg);
// lpMsg : MSG* out
// hWnd : HWND optional
// wMsgFilterMin : DWORD
// wMsgFilterMax : DWORD
// wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE
// 構造体/GUIDへのポインタは cdef が通るよう void* で表記(実型は各引数コメント参照)。値渡し構造体・enum は対応する typedef を cdef に追加すること。
// WINAPI(stdcall): x64 では呼出規約が統一されるため問題なし。x86 では __stdcall 対応のラッパが必要な場合あり。

import com.sun.jna.*;
import com.sun.jna.ptr.*;
import com.sun.jna.win32.StdCallLibrary;
import com.sun.jna.win32.W32APIOptions;

public interface User32 extends StdCallLibrary {
    User32 INSTANCE = Native.load("user32", User32.class, W32APIOptions.ASCII_OPTIONS);
    boolean PeekMessageA(
        Pointer lpMsg,   // MSG* out
        Pointer hWnd,   // HWND optional
        int wMsgFilterMin,   // DWORD
        int wMsgFilterMax,   // DWORD
        int wRemoveMsg   // PEEK_MESSAGE_REMOVE_TYPE
    );
}

@[Link("user32")]
lib LibUSER32
  fun PeekMessageA = PeekMessageA(
    lpMsg : MSG*,   # MSG* out
    hWnd : Void*,   # HWND optional
    wMsgFilterMin : UInt32,   # DWORD
    wMsgFilterMax : UInt32,   # DWORD
    wRemoveMsg : UInt32   # PEEK_MESSAGE_REMOVE_TYPE
  ) : Int32
end
# 構造体/GUID/enum は lib 内に対応する型定義が必要。
# 呼出規約: x64 は規約統一のため OK。x86(32bit)は WINAPI=stdcall だが Crystal の fun に stdcall 付与構文がなく非対応。

import 'dart:ffi';
import 'package:ffi/ffi.dart';

typedef PeekMessageANative = Int32 Function(Pointer<Void>, Pointer<Void>, Uint32, Uint32, Uint32);
typedef PeekMessageADart = int Function(Pointer<Void>, Pointer<Void>, int, int, int);
final PeekMessageA = DynamicLibrary.open('USER32.dll')
    .lookupFunction<PeekMessageANative, PeekMessageADart>('PeekMessageA');
// lpMsg : MSG* out -> Pointer<Void>
// hWnd : HWND optional -> Pointer<Void>
// wMsgFilterMin : DWORD -> Uint32
// wMsgFilterMax : DWORD -> Uint32
// wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> Uint32
// 文字列は package:ffi の "...".toNativeUtf16()/toNativeUtf8() で変換。

{$mode objfpc}{$H+}
function PeekMessageA(
  lpMsg: Pointer;   // MSG* out
  hWnd: THandle;   // HWND optional
  wMsgFilterMin: DWORD;   // DWORD
  wMsgFilterMax: DWORD;   // DWORD
  wRemoveMsg: DWORD   // PEEK_MESSAGE_REMOVE_TYPE
): BOOL; stdcall;
  external 'USER32.dll' name 'PeekMessageA';

import Foreign
import Foreign.C.Types
import Foreign.C.String

foreign import stdcall safe "PeekMessageA"
  c_PeekMessageA :: Ptr () -> Ptr () -> Word32 -> Word32 -> Word32 -> IO CInt
-- lpMsg : MSG* out -> Ptr ()
-- hWnd : HWND optional -> Ptr ()
-- wMsgFilterMin : DWORD -> Word32
-- wMsgFilterMax : DWORD -> Word32
-- wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> Word32
-- 要 GHC(Windows)。stdcall は x64 では ccall として扱われる。ブロックする API は safe 呼び出し推奨。

open Ctypes
open Foreign

let peekmessagea =
  foreign "PeekMessageA"
    ((ptr void) @-> (ptr void) @-> uint32_t @-> uint32_t @-> uint32_t @-> returning int32_t)
(* lpMsg : MSG* out -> (ptr void) *)
(* hWnd : HWND optional -> (ptr void) *)
(* wMsgFilterMin : DWORD -> uint32_t *)
(* wMsgFilterMax : DWORD -> uint32_t *)
(* wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> uint32_t *)
(* foreign は cdecl 前提。x64 Windows では WINAPI と一致。構造体は ctypes structure を定義のこと。 *)

(cffi:define-foreign-library user32 (t "USER32.dll"))
(cffi:use-foreign-library user32)

(cffi:defcfun ("PeekMessageA" peek-message-a :convention :stdcall) :int32
  (lp-msg :pointer)   ; MSG* out
  (h-wnd :pointer)   ; HWND optional
  (w-msg-filter-min :uint32)   ; DWORD
  (w-msg-filter-max :uint32)   ; DWORD
  (w-remove-msg :uint32))   ; PEEK_MESSAGE_REMOVE_TYPE
; isize/usize(INT_PTR/SIZE_T)は x64 前提で :int64/:uint64。x86 では :int32/:uint32。

use Win32::API;
my $PeekMessageA = Win32::API::More->new('USER32',
    'BOOL PeekMessageA(LPVOID lpMsg, HANDLE hWnd, DWORD wMsgFilterMin, DWORD wMsgFilterMax, DWORD wRemoveMsg)');
# my $ret = $PeekMessageA->Call($lpMsg, $hWnd, $wMsgFilterMin, $wMsgFilterMax, $wRemoveMsg);
# lpMsg : MSG* out -> LPVOID
# hWnd : HWND optional -> HANDLE
# wMsgFilterMin : DWORD -> DWORD
# wMsgFilterMax : DWORD -> DWORD
# wRemoveMsg : PEEK_MESSAGE_REMOVE_TYPE -> DWORD
# 値渡し構造体は pack() した文字列、または Win32::API::Struct を使用。