int MultiByteToWideChar(UINT CodePage, DWORD dwFlags, LPCCH lpMultiByteStr, int cbMultiByte, LPWSTR lpWideCharStr, int cchWideChar);
int WideCharToMultiByte(UINT CodePage, DWORD dwFlags, LPCWCH lpWideCharStr, int cchWideChar, LPSTR lpMultiByteStr, int cchMultiByte, LPCCH lpDefaultChar, LPBOOL pfUsedDefaultChar);
]])
d_4.CP_ACP = 0
d_4.CP_UTF8 = 65001
--~ 算机_基统_窗群
function d_4.m2w(input, o1)
  local wlen = ffi.C.MultiByteToWideChar(o1 or d_4.CP_ACP, 0, input, #input, nil, 0)
  local wstr = ffi.new("wchar_t[?]", wlen + 1)
  ffi.C.MultiByteToWideChar(o1 or d_4.CP_ACP, 0, input, #input, wstr, wlen)
  return wstr, wlen
end
function d_4.w2m(wstr, wlen, o1)
  local len = ffi.C.WideCharToMultiByte(o1 or d_4.CP_ACP, 0, wstr, wlen or -1, nil, 0, nil, nil)
  local str = ffi.new("char[?]", len)
  ffi.C.WideCharToMultiByte(o1 or d_4.CP_ACP, 0, wstr, wlen or -1, str, len, nil, nil)
  return ffi.string(str, len)
end
--~ 通用大字集_八位
function d_4.u8_to_a(input)
  return d_4.w2m(d_4.m2w(input, d_4.CP_UTF8))
end
function d_4.a_to_u8(input)
  local k1, k2 = d_4.m2w(input)
  return d_4.w2m(k1, k2, d_4.CP_UTF8)
end
return d_4