如何为 Delphi/Free Pascal/Lazarus DLL 创建 C-Header - 数据类型

Question

对于我的应用程序，我需要使用 stdcall 从 Delphi 创建一个 DLL（更准确地说是在 Lazarus IDE 中编写的由 Linux 下的 free pascal 编译的 Delphi 兼容代码）。
在使用该 DLL 时（例如在 Matlab 中），当然需要元信息来传递参数 - 通常通过头文件实现。 我正在寻找一种在delphi源代码上运行的工具。类似h2pas-reverse。
我的研究没有结果。我想，没有这样的工具，我想找一个表或其他信息，Delphi/Pascal 数据类型如何映射到 C 类型以及如何处理记录。

Answer 1

当 Delphi 有 -JPH 开关时，我使用以下构造从 Delphi 5 代码生成与 Visual C++ 6 的 C 模式编译器兼容的头文件（请参阅下面的注释）。

请注意，我从 Delphi 5 开始就没有使用过这个，但是从那以后这个开关已经被扩展了：

在某处，JPHNE switch 已添加到dcc32 命令行编译器：

  -JPHNE = Generate C++ .obj file, .hpp file, in namespace, export all

Rudy Velthuis 有一个nice article using the JPHNE switch。

它当然不能处理所有类型，您将需要相当多的 HPPEMIT 和 EXTERNALSYM 指令。

我将我的Delphi 5 to Visual C++ 6 HPP conversion from back then 上传到 BitBucket。

它会生成 .hpp 文件以导入用 Delphi 编写的 DLL。

Delphi 5 时代的笔记：

{ Visual C++ 6 does not like nested structs/unions the way that BC++ can handle them.
  Visual C++ 6 requires the "typedef" to be present AND the typename AFTER the struct definition.
  You will see this when defining TConversationId, TReturnKey and other types that depend on nested structs/unions

  The trick is to perform these steps each and every time this unit changes:
    - Generate this unit once with all the EXTERNALSYM disabled.
      - Then the DCC32 -JPH will generate the basic structs for them.
    - Copy all the nested struct and union definitions to this file
    - Embed the definitions with (*$HPPEMIT '' *)
    - Append the typename at the end of the struct definition
    - Enable all the EXTERNALSYM again
    - Regenerate the HPP files by using DCC32 -JPH
  To make this process easier, we have introduced two new conditional defines:
    - BCB - disable EXTERNALSYM, disable HPPEMIT
    - VC6 - enable EXTERNALSYM, enable HPPEMIT

  A similar thing is with these constructions that VC6 does not like those either:
    - short strings (BCB defines them as "SmallString<##>" which VC6 does not like).
    - short integers (BCB defines them as "Shortint" so we have included an HPPEMIT for that)
}

{$ifdef win32}
  { important! Makes sure that the all enumerated types fit in exactly one byte each! }
  {$Z1}

  { force the C/C++ HPP header files to have the C/C++ compiler pack structure elements on byte boundaries }
  {$ifdef BCB}
    {$HPPEMIT '#pragma option push -a1' }
  {$endif BCB}
{$endif win32}