MultiByteToWideChar

// KERNEL32.dll
#include <windows.h>

INT MultiByteToWideChar(
    DWORD CodePage,
    MULTI_BYTE_TO_WIDE_CHAR_FLAGS dwFlags,
    LPCSTR lpMultiByteStr,
    INT cbMultiByte,
    LPWSTR lpWideCharStr,   // optional
    INT cchWideChar
);

<DllImport("KERNEL32.dll", SetLastError:=True, ExactSpelling:=True)>
Public Shared Function MultiByteToWideChar(
    CodePage As UInteger,   ' DWORD
    dwFlags As UInteger,   ' MULTI_BYTE_TO_WIDE_CHAR_FLAGS
    <MarshalAs(UnmanagedType.LPStr)> lpMultiByteStr As String,   ' LPCSTR
    cbMultiByte As Integer,   ' INT
    <MarshalAs(UnmanagedType.LPWStr)> lpWideCharStr As System.Text.StringBuilder,   ' LPWSTR optional, out
    cchWideChar As Integer   ' INT
) As Integer
End Function

' CodePage : DWORD
' dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS
' lpMultiByteStr : LPCSTR
' cbMultiByte : INT
' lpWideCharStr : LPWSTR optional, out
' cchWideChar : INT
Declare PtrSafe Function MultiByteToWideChar Lib "kernel32" ( _
    ByVal CodePage As Long, _
    ByVal dwFlags As Long, _
    ByVal lpMultiByteStr As String, _
    ByVal cbMultiByte As Long, _
    ByVal lpWideCharStr As LongPtr, _
    ByVal cchWideChar 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

MultiByteToWideChar = ctypes.windll.kernel32.MultiByteToWideChar
MultiByteToWideChar.restype = ctypes.c_int
MultiByteToWideChar.argtypes = [
    wintypes.DWORD,  # CodePage : DWORD
    wintypes.DWORD,  # dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS
    wintypes.LPCSTR,  # lpMultiByteStr : LPCSTR
    ctypes.c_int,  # cbMultiByte : INT
    wintypes.LPWSTR,  # lpWideCharStr : LPWSTR optional, out
    ctypes.c_int,  # cchWideChar : INT
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('KERNEL32.dll')
MultiByteToWideChar = Fiddle::Function.new(
  lib['MultiByteToWideChar'],
  [
    -Fiddle::TYPE_INT,  # CodePage : DWORD
    -Fiddle::TYPE_INT,  # dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS
    Fiddle::TYPE_VOIDP,  # lpMultiByteStr : LPCSTR
    Fiddle::TYPE_INT,  # cbMultiByte : INT
    Fiddle::TYPE_VOIDP,  # lpWideCharStr : LPWSTR optional, out
    Fiddle::TYPE_INT,  # cchWideChar : INT
  ],
  Fiddle::TYPE_INT)

#[link(name = "kernel32")]
extern "system" {
    fn MultiByteToWideChar(
        CodePage: u32,  // DWORD
        dwFlags: u32,  // MULTI_BYTE_TO_WIDE_CHAR_FLAGS
        lpMultiByteStr: *const u8,  // LPCSTR
        cbMultiByte: i32,  // INT
        lpWideCharStr: *mut u16,  // LPWSTR optional, out
        cchWideChar: i32  // INT
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("KERNEL32.dll", SetLastError = true)]
public static extern int MultiByteToWideChar(uint CodePage, uint dwFlags, [MarshalAs(UnmanagedType.LPStr)] string lpMultiByteStr, int cbMultiByte, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder lpWideCharStr, int cchWideChar);
"@
$api = Add-Type -MemberDefinition $sig -Name 'KERNEL32_MultiByteToWideChar' -Namespace Win32 -PassThru
# $api::MultiByteToWideChar(CodePage, dwFlags, lpMultiByteStr, cbMultiByte, lpWideCharStr, cchWideChar)

#uselib "KERNEL32.dll"
#func global MultiByteToWideChar "MultiByteToWideChar" sptr, sptr, sptr, sptr, sptr, sptr
; MultiByteToWideChar CodePage, dwFlags, lpMultiByteStr, cbMultiByte, varptr(lpWideCharStr), cchWideChar   ; 戻り値は stat
; CodePage : DWORD -> "sptr"
; dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS -> "sptr"
; lpMultiByteStr : LPCSTR -> "sptr"
; cbMultiByte : INT -> "sptr"
; lpWideCharStr : LPWSTR optional, out -> "sptr"
; cchWideChar : INT -> "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。

#uselib "KERNEL32.dll"
#cfunc global MultiByteToWideChar "MultiByteToWideChar" int, int, str, int, var, int
; res = MultiByteToWideChar(CodePage, dwFlags, lpMultiByteStr, cbMultiByte, lpWideCharStr, cchWideChar)
; CodePage : DWORD -> "int"
; dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS -> "int"
; lpMultiByteStr : LPCSTR -> "str"
; cbMultiByte : INT -> "int"
; lpWideCharStr : LPWSTR optional, out -> "var"
; cchWideChar : INT -> "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。

; INT MultiByteToWideChar(DWORD CodePage, MULTI_BYTE_TO_WIDE_CHAR_FLAGS dwFlags, LPCSTR lpMultiByteStr, INT cbMultiByte, LPWSTR lpWideCharStr, INT cchWideChar)
#uselib "KERNEL32.dll"
#cfunc global MultiByteToWideChar "MultiByteToWideChar" int, int, str, int, var, int
; res = MultiByteToWideChar(CodePage, dwFlags, lpMultiByteStr, cbMultiByte, lpWideCharStr, cchWideChar)
; CodePage : DWORD -> "int"
; dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS -> "int"
; lpMultiByteStr : LPCSTR -> "str"
; cbMultiByte : INT -> "int"
; lpWideCharStr : LPWSTR optional, out -> "var"
; cchWideChar : INT -> "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 (
	kernel32 = windows.NewLazySystemDLL("KERNEL32.dll")
	procMultiByteToWideChar = kernel32.NewProc("MultiByteToWideChar")
)

// CodePage (DWORD), dwFlags (MULTI_BYTE_TO_WIDE_CHAR_FLAGS), lpMultiByteStr (LPCSTR), cbMultiByte (INT), lpWideCharStr (LPWSTR optional, out), cchWideChar (INT)
r1, _, err := procMultiByteToWideChar.Call(
	uintptr(CodePage),
	uintptr(dwFlags),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(lpMultiByteStr))),
	uintptr(cbMultiByte),
	uintptr(lpWideCharStr),
	uintptr(cchWideChar),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // INT

function MultiByteToWideChar(
  CodePage: DWORD;   // DWORD
  dwFlags: DWORD;   // MULTI_BYTE_TO_WIDE_CHAR_FLAGS
  lpMultiByteStr: PAnsiChar;   // LPCSTR
  cbMultiByte: Integer;   // INT
  lpWideCharStr: PWideChar;   // LPWSTR optional, out
  cchWideChar: Integer   // INT
): Integer; stdcall;
  external 'KERNEL32.dll' name 'MultiByteToWideChar';

result := DllCall("KERNEL32\MultiByteToWideChar"
    , "UInt", CodePage   ; DWORD
    , "UInt", dwFlags   ; MULTI_BYTE_TO_WIDE_CHAR_FLAGS
    , "AStr", lpMultiByteStr   ; LPCSTR
    , "Int", cbMultiByte   ; INT
    , "Ptr", lpWideCharStr   ; LPWSTR optional, out
    , "Int", cchWideChar   ; INT
    , "Int")   ; return: INT

●MultiByteToWideChar(CodePage, dwFlags, lpMultiByteStr, cbMultiByte, lpWideCharStr, cchWideChar) = DLL("KERNEL32.dll", "int MultiByteToWideChar(dword, dword, char*, int, char*, int)")
# 呼び出し: MultiByteToWideChar(CodePage, dwFlags, lpMultiByteStr, cbMultiByte, lpWideCharStr, cchWideChar)
# CodePage : DWORD -> "dword"
# dwFlags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS -> "dword"
# lpMultiByteStr : LPCSTR -> "char*"
# cbMultiByte : INT -> "int"
# lpWideCharStr : LPWSTR optional, out -> "char*"
# cchWideChar : INT -> "int"
# 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)。