EngMultiByteToUnicodeN

// GDI32.dll
#include <windows.h>

void EngMultiByteToUnicodeN(
    LPWSTR UnicodeString,
    DWORD MaxBytesInUnicodeString,
    DWORD* BytesInUnicodeString,   // optional
    LPSTR MultiByteString,
    DWORD BytesInMultiByteString
);

<DllImport("GDI32.dll", ExactSpelling:=True)>
Public Shared Sub EngMultiByteToUnicodeN(
    <MarshalAs(UnmanagedType.LPWStr)> UnicodeString As System.Text.StringBuilder,   ' LPWSTR out
    MaxBytesInUnicodeString As UInteger,   ' DWORD
    BytesInUnicodeString As IntPtr,   ' DWORD* optional, out
    <MarshalAs(UnmanagedType.LPStr)> MultiByteString As String,   ' LPSTR
    BytesInMultiByteString As UInteger   ' DWORD
)
End Sub

' UnicodeString : LPWSTR out
' MaxBytesInUnicodeString : DWORD
' BytesInUnicodeString : DWORD* optional, out
' MultiByteString : LPSTR
' BytesInMultiByteString : DWORD
Declare PtrSafe Sub EngMultiByteToUnicodeN Lib "gdi32" ( _
    ByVal UnicodeString As LongPtr, _
    ByVal MaxBytesInUnicodeString As Long, _
    ByVal BytesInUnicodeString As LongPtr, _
    ByVal MultiByteString As String, _
    ByVal BytesInMultiByteString As Long)
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

EngMultiByteToUnicodeN = ctypes.windll.gdi32.EngMultiByteToUnicodeN
EngMultiByteToUnicodeN.restype = None
EngMultiByteToUnicodeN.argtypes = [
    wintypes.LPWSTR,  # UnicodeString : LPWSTR out
    wintypes.DWORD,  # MaxBytesInUnicodeString : DWORD
    ctypes.POINTER(wintypes.DWORD),  # BytesInUnicodeString : DWORD* optional, out
    wintypes.LPCSTR,  # MultiByteString : LPSTR
    wintypes.DWORD,  # BytesInMultiByteString : DWORD
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('GDI32.dll')
EngMultiByteToUnicodeN = Fiddle::Function.new(
  lib['EngMultiByteToUnicodeN'],
  [
    Fiddle::TYPE_VOIDP,  # UnicodeString : LPWSTR out
    -Fiddle::TYPE_INT,  # MaxBytesInUnicodeString : DWORD
    Fiddle::TYPE_VOIDP,  # BytesInUnicodeString : DWORD* optional, out
    Fiddle::TYPE_VOIDP,  # MultiByteString : LPSTR
    -Fiddle::TYPE_INT,  # BytesInMultiByteString : DWORD
  ],
  Fiddle::TYPE_VOID)

#[link(name = "gdi32")]
extern "system" {
    fn EngMultiByteToUnicodeN(
        UnicodeString: *mut u16,  // LPWSTR out
        MaxBytesInUnicodeString: u32,  // DWORD
        BytesInUnicodeString: *mut u32,  // DWORD* optional, out
        MultiByteString: *mut u8,  // LPSTR
        BytesInMultiByteString: u32  // DWORD
    );
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("GDI32.dll")]
public static extern void EngMultiByteToUnicodeN([MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder UnicodeString, uint MaxBytesInUnicodeString, IntPtr BytesInUnicodeString, [MarshalAs(UnmanagedType.LPStr)] string MultiByteString, uint BytesInMultiByteString);
"@
$api = Add-Type -MemberDefinition $sig -Name 'GDI32_EngMultiByteToUnicodeN' -Namespace Win32 -PassThru
# $api::EngMultiByteToUnicodeN(UnicodeString, MaxBytesInUnicodeString, BytesInUnicodeString, MultiByteString, BytesInMultiByteString)

#uselib "GDI32.dll"
#func global EngMultiByteToUnicodeN "EngMultiByteToUnicodeN" sptr, sptr, sptr, sptr, sptr
; EngMultiByteToUnicodeN varptr(UnicodeString), MaxBytesInUnicodeString, varptr(BytesInUnicodeString), MultiByteString, BytesInMultiByteString
; UnicodeString : LPWSTR out -> "sptr"
; MaxBytesInUnicodeString : DWORD -> "sptr"
; BytesInUnicodeString : DWORD* optional, out -> "sptr"
; MultiByteString : LPSTR -> "sptr"
; BytesInMultiByteString : DWORD -> "sptr"

#uselib "GDI32.dll"
#func global EngMultiByteToUnicodeN "EngMultiByteToUnicodeN" var, int, var, str, int
; EngMultiByteToUnicodeN UnicodeString, MaxBytesInUnicodeString, BytesInUnicodeString, MultiByteString, BytesInMultiByteString
; UnicodeString : LPWSTR out -> "var"
; MaxBytesInUnicodeString : DWORD -> "int"
; BytesInUnicodeString : DWORD* optional, out -> "var"
; MultiByteString : LPSTR -> "str"
; BytesInMultiByteString : DWORD -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; void EngMultiByteToUnicodeN(LPWSTR UnicodeString, DWORD MaxBytesInUnicodeString, DWORD* BytesInUnicodeString, LPSTR MultiByteString, DWORD BytesInMultiByteString)
#uselib "GDI32.dll"
#func global EngMultiByteToUnicodeN "EngMultiByteToUnicodeN" var, int, var, str, int
; EngMultiByteToUnicodeN UnicodeString, MaxBytesInUnicodeString, BytesInUnicodeString, MultiByteString, BytesInMultiByteString
; UnicodeString : LPWSTR out -> "var"
; MaxBytesInUnicodeString : DWORD -> "int"
; BytesInUnicodeString : DWORD* optional, out -> "var"
; MultiByteString : LPSTR -> "str"
; BytesInMultiByteString : DWORD -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

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

var (
	gdi32 = windows.NewLazySystemDLL("GDI32.dll")
	procEngMultiByteToUnicodeN = gdi32.NewProc("EngMultiByteToUnicodeN")
)

// UnicodeString (LPWSTR out), MaxBytesInUnicodeString (DWORD), BytesInUnicodeString (DWORD* optional, out), MultiByteString (LPSTR), BytesInMultiByteString (DWORD)
r1, _, err := procEngMultiByteToUnicodeN.Call(
	uintptr(UnicodeString),
	uintptr(MaxBytesInUnicodeString),
	uintptr(BytesInUnicodeString),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(MultiByteString))),
	uintptr(BytesInMultiByteString),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // void

procedure EngMultiByteToUnicodeN(
  UnicodeString: PWideChar;   // LPWSTR out
  MaxBytesInUnicodeString: DWORD;   // DWORD
  BytesInUnicodeString: Pointer;   // DWORD* optional, out
  MultiByteString: PAnsiChar;   // LPSTR
  BytesInMultiByteString: DWORD   // DWORD
); stdcall;
  external 'GDI32.dll' name 'EngMultiByteToUnicodeN';

result := DllCall("GDI32\EngMultiByteToUnicodeN"
    , "Ptr", UnicodeString   ; LPWSTR out
    , "UInt", MaxBytesInUnicodeString   ; DWORD
    , "Ptr", BytesInUnicodeString   ; DWORD* optional, out
    , "AStr", MultiByteString   ; LPSTR
    , "UInt", BytesInMultiByteString   ; DWORD
    , "Int")   ; return: void

●EngMultiByteToUnicodeN(UnicodeString, MaxBytesInUnicodeString, BytesInUnicodeString, MultiByteString, BytesInMultiByteString) = DLL("GDI32.dll", "int EngMultiByteToUnicodeN(char*, dword, void*, char*, dword)")
# 呼び出し: EngMultiByteToUnicodeN(UnicodeString, MaxBytesInUnicodeString, BytesInUnicodeString, MultiByteString, BytesInMultiByteString)
# UnicodeString : LPWSTR out -> "char*"
# MaxBytesInUnicodeString : DWORD -> "dword"
# BytesInUnicodeString : DWORD* optional, out -> "void*"
# MultiByteString : LPSTR -> "char*"
# BytesInMultiByteString : DWORD -> "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)。