VarDateFromR4

// OLEAUT32.dll
#include <windows.h>

HRESULT VarDateFromR4(
    FLOAT fltIn,
    DOUBLE* pdateOut
);

<DllImport("OLEAUT32.dll", ExactSpelling:=True)>
Public Shared Function VarDateFromR4(
    fltIn As Single,   ' FLOAT
    <Out> ByRef pdateOut As Double   ' DOUBLE* out
) As Integer
End Function

' fltIn : FLOAT
' pdateOut : DOUBLE* out
Declare PtrSafe Function VarDateFromR4 Lib "oleaut32" ( _
    ByVal fltIn As Single, _
    ByRef pdateOut As Double) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

VarDateFromR4 = ctypes.windll.oleaut32.VarDateFromR4
VarDateFromR4.restype = ctypes.c_int
VarDateFromR4.argtypes = [
    ctypes.c_float,  # fltIn : FLOAT
    ctypes.POINTER(ctypes.c_double),  # pdateOut : DOUBLE* out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('OLEAUT32.dll')
VarDateFromR4 = Fiddle::Function.new(
  lib['VarDateFromR4'],
  [
    Fiddle::TYPE_FLOAT,  # fltIn : FLOAT
    Fiddle::TYPE_VOIDP,  # pdateOut : DOUBLE* out
  ],
  Fiddle::TYPE_INT)

#[link(name = "oleaut32")]
extern "system" {
    fn VarDateFromR4(
        fltIn: f32,  // FLOAT
        pdateOut: *mut f64  // DOUBLE* out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("OLEAUT32.dll")]
public static extern int VarDateFromR4(float fltIn, out double pdateOut);
"@
$api = Add-Type -MemberDefinition $sig -Name 'OLEAUT32_VarDateFromR4' -Namespace Win32 -PassThru
# $api::VarDateFromR4(fltIn, pdateOut)

#uselib "OLEAUT32.dll"
#func global VarDateFromR4 "VarDateFromR4" float, sptr
; VarDateFromR4 fltIn, varptr(pdateOut)   ; 戻り値は stat
; fltIn : FLOAT -> "float"
; pdateOut : DOUBLE* 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 "OLEAUT32.dll"
#cfunc global VarDateFromR4 "VarDateFromR4" float, var
; res = VarDateFromR4(fltIn, pdateOut)
; fltIn : FLOAT -> "float"
; pdateOut : DOUBLE* out -> "var"
; ※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。

; HRESULT VarDateFromR4(FLOAT fltIn, DOUBLE* pdateOut)
#uselib "OLEAUT32.dll"
#cfunc global VarDateFromR4 "VarDateFromR4" float, var
; res = VarDateFromR4(fltIn, pdateOut)
; fltIn : FLOAT -> "float"
; pdateOut : DOUBLE* out -> "var"
; ※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 (
	"math"
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	oleaut32 = windows.NewLazySystemDLL("OLEAUT32.dll")
	procVarDateFromR4 = oleaut32.NewProc("VarDateFromR4")
)

// fltIn (FLOAT), pdateOut (DOUBLE* out)
r1, _, err := procVarDateFromR4.Call(
	uintptr(math.Float32bits(fltIn)),
	uintptr(pdateOut),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HRESULT
// 注意: float/double 引数は proc.Call では XMM レジスタに渡せません。
// windows.SyscallN(proc.Addr(), math.Float64bits(x), ...) もしくは cgo を使用してください。

function VarDateFromR4(
  fltIn: Single;   // FLOAT
  pdateOut: Pointer   // DOUBLE* out
): Integer; stdcall;
  external 'OLEAUT32.dll' name 'VarDateFromR4';

result := DllCall("OLEAUT32\VarDateFromR4"
    , "Float", fltIn   ; FLOAT
    , "Ptr", pdateOut   ; DOUBLE* out
    , "Int")   ; return: HRESULT

●VarDateFromR4(fltIn, pdateOut) = DLL("OLEAUT32.dll", "int VarDateFromR4(float, void*)")
# 呼び出し: VarDateFromR4(fltIn, pdateOut)
# fltIn : FLOAT -> "float"
# pdateOut : DOUBLE* 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)。