ucnv_getDisplayName

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

INT ucnv_getDisplayName(
    const UConverter* converter,
    LPCSTR displayLocale,
    WORD* displayName,
    INT displayNameCapacity,
    UErrorCode* err
);

<DllImport("icuuc.dll", ExactSpelling:=True, CallingConvention:=CallingConvention.Cdecl)>
Public Shared Function ucnv_getDisplayName(
    ByRef converter As IntPtr,   ' UConverter*
    <MarshalAs(UnmanagedType.LPStr)> displayLocale As String,   ' LPCSTR
    ByRef displayName As UShort,   ' WORD* in/out
    displayNameCapacity As Integer,   ' INT
    ByRef err As Integer   ' UErrorCode* in/out
) As Integer
End Function

' converter : UConverter*
' displayLocale : LPCSTR
' displayName : WORD* in/out
' displayNameCapacity : INT
' err : UErrorCode* in/out
Declare PtrSafe Function ucnv_getDisplayName Lib "icuuc" ( _
    ByRef converter As LongPtr, _
    ByVal displayLocale As String, _
    ByRef displayName As Integer, _
    ByVal displayNameCapacity As Long, _
    ByRef err 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

ucnv_getDisplayName = ctypes.cdll.icuuc.ucnv_getDisplayName
ucnv_getDisplayName.restype = ctypes.c_int
ucnv_getDisplayName.argtypes = [
    ctypes.c_void_p,  # converter : UConverter*
    wintypes.LPCSTR,  # displayLocale : LPCSTR
    ctypes.POINTER(ctypes.c_ushort),  # displayName : WORD* in/out
    ctypes.c_int,  # displayNameCapacity : INT
    ctypes.c_void_p,  # err : UErrorCode* in/out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('icuuc.dll')
ucnv_getDisplayName = Fiddle::Function.new(
  lib['ucnv_getDisplayName'],
  [
    Fiddle::TYPE_VOIDP,  # converter : UConverter*
    Fiddle::TYPE_VOIDP,  # displayLocale : LPCSTR
    Fiddle::TYPE_VOIDP,  # displayName : WORD* in/out
    Fiddle::TYPE_INT,  # displayNameCapacity : INT
    Fiddle::TYPE_VOIDP,  # err : UErrorCode* in/out
  ],
  Fiddle::TYPE_INT, Fiddle::Function::CDECL)

#[link(name = "icuuc")]
extern "C" {
    fn ucnv_getDisplayName(
        converter: *const isize,  // UConverter*
        displayLocale: *const u8,  // LPCSTR
        displayName: *mut u16,  // WORD* in/out
        displayNameCapacity: i32,  // INT
        err: *mut i32  // UErrorCode* in/out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("icuuc.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern int ucnv_getDisplayName(ref IntPtr converter, [MarshalAs(UnmanagedType.LPStr)] string displayLocale, ref ushort displayName, int displayNameCapacity, ref int err);
"@
$api = Add-Type -MemberDefinition $sig -Name 'icuuc_ucnv_getDisplayName' -Namespace Win32 -PassThru
# $api::ucnv_getDisplayName(converter, displayLocale, displayName, displayNameCapacity, err)

#uselib "icuuc.dll"
#func global ucnv_getDisplayName "ucnv_getDisplayName" sptr, sptr, sptr, sptr, sptr
; ucnv_getDisplayName converter, displayLocale, varptr(displayName), displayNameCapacity, err   ; 戻り値は stat
; converter : UConverter* -> "sptr"
; displayLocale : LPCSTR -> "sptr"
; displayName : WORD* in/out -> "sptr"
; displayNameCapacity : INT -> "sptr"
; err : UErrorCode* in/out -> "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 "icuuc.dll"
#cfunc global ucnv_getDisplayName "ucnv_getDisplayName" int, str, var, int, int
; res = ucnv_getDisplayName(converter, displayLocale, displayName, displayNameCapacity, err)
; converter : UConverter* -> "int"
; displayLocale : LPCSTR -> "str"
; displayName : WORD* in/out -> "var"
; displayNameCapacity : INT -> "int"
; err : UErrorCode* in/out -> "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 ucnv_getDisplayName(UConverter* converter, LPCSTR displayLocale, WORD* displayName, INT displayNameCapacity, UErrorCode* err)
#uselib "icuuc.dll"
#cfunc global ucnv_getDisplayName "ucnv_getDisplayName" int, str, var, int, int
; res = ucnv_getDisplayName(converter, displayLocale, displayName, displayNameCapacity, err)
; converter : UConverter* -> "int"
; displayLocale : LPCSTR -> "str"
; displayName : WORD* in/out -> "var"
; displayNameCapacity : INT -> "int"
; err : UErrorCode* in/out -> "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 (
	icuuc = windows.NewLazySystemDLL("icuuc.dll")
	procucnv_getDisplayName = icuuc.NewProc("ucnv_getDisplayName")
)

// converter (UConverter*), displayLocale (LPCSTR), displayName (WORD* in/out), displayNameCapacity (INT), err (UErrorCode* in/out)
r1, _, err := procucnv_getDisplayName.Call(
	uintptr(converter),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(displayLocale))),
	uintptr(displayName),
	uintptr(displayNameCapacity),
	uintptr(err),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // INT

function ucnv_getDisplayName(
  converter: Pointer;   // UConverter*
  displayLocale: PAnsiChar;   // LPCSTR
  displayName: Pointer;   // WORD* in/out
  displayNameCapacity: Integer;   // INT
  err: Pointer   // UErrorCode* in/out
): Integer; cdecl;
  external 'icuuc.dll' name 'ucnv_getDisplayName';

result := DllCall("icuuc\ucnv_getDisplayName"
    , "Ptr", converter   ; UConverter*
    , "AStr", displayLocale   ; LPCSTR
    , "Ptr", displayName   ; WORD* in/out
    , "Int", displayNameCapacity   ; INT
    , "Ptr", err   ; UErrorCode* in/out
    , "Cdecl Int")   ; return: INT

●ucnv_getDisplayName(converter, displayLocale, displayName, displayNameCapacity, err) = DLL("icuuc.dll", "int ucnv_getDisplayName(void*, char*, void*, int, void*)")
# 呼び出し: ucnv_getDisplayName(converter, displayLocale, displayName, displayNameCapacity, err)
# converter : UConverter* -> "void*"
# displayLocale : LPCSTR -> "char*"
# displayName : WORD* in/out -> "void*"
# displayNameCapacity : INT -> "int"
# err : UErrorCode* in/out -> "void*"
# 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)。
# ※cdecl関数。DLL()宣言はstdcall前提。cdeclは EXEC_PTR(`cdecl`,…) を使用。