将FPC .o文件链接到Delphi中 [英] Linking FPC .o files into Delphi

问题描述

如何将FPC .o从库链接到Delphi可执行文件.当我尝试链接以下代码时，会收到一堆不满意的前向或外部声明.

How can I link a FPC .o from a library to a Delphi executable. When I try to link the following code I get a bunch of unsatisfied forward or external declarations.

library project1;

{$mode objfpc}{$H+}

uses
  Classes
  { you can add units after this };

function Test: Integer;
begin
  Result := -1;
end;

begin
end.


[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'INIT$_$SYSTEM'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FINALIZE$_$OBJPAS'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'INIT$_$LNFODWRF'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FINALIZE$_$LNFODWRF'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'INIT$_$FPINTRES'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FINALIZE$_$WINDIRS'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'SYSUTILS$_$TENCODING_$__$$_create'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'SYSUTILS$_$TENCODING_$__$$_destroy'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'INIT$_$SYSUTILS'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FINALIZE$_$SYSUTILS'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'INIT$_$TYPINFO'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FINALIZE$_$TYPINFO'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'INIT$_$CLASSES'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FINALIZE$_$CLASSES'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'THREADVARLIST_$SYSTEM'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'THREADVARLIST_$CLASSES'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'RESSTR_$RTLCONSTS_$$_START'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'RESSTR_$RTLCONSTS_$$_END'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'RESSTR_$SYSCONST_$$_START'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'RESSTR_$SYSCONST_$$_END'
[dcc64 Error] Project2.dpr(170): E2065 Unsatisfied forward or external declaration: 'FPC_LIBINITIALIZEUNITS' 

推荐答案

至少在书面规定的情况下，您几乎不可能进行这项工作.不满意的声明来自FPC运行时.您也需要链接它，或在Delphi中重新实现它.两种选择都不可行.

It is highly unlikely that you will be able to make this work, at least as written. The unsatisfied declarations are from the FPC runtime. You'd need to link that too, or re-implement it in Delphi. Neither option is terribly viable.

当然，如果删除对Classes单元的引用，并将此简单函数放在单独的代码单元而不是库单元中，则可能没有不满意的声明是合理的.就是说，您肯定正在探索此问题，因为您想使用实际执行某些操作的FPC代码.这样做之后，您将立即回到第一个平方.

Of course, if you removed the reference to the Classes unit, and put this simple function in separate code unit rather than a library unit then it is plausible that there might be no unsatisfied declarations. That said, surely you are exploring this because you want to use FPC code that actually does something. And as soon as you do that, then you will be right back to square one.

解决此问题的方法是动态链接到FPC代码.将FPC代码编译到一个库中，并动态链接到该库.

The way out of this problem is to link to the FPC code dynamically. Compile the FPC code into a library and link to that library dynamically.

只是为了好玩，我试图将FPC对象链接到Delphi程序. FPC单元:

Just for fun I tried to link an FPC object to a Delphi program. The FPC unit:

unit unit1;

interface

implementation

function Test(i: Integer): Integer; cdecl;
begin
  Test := i*42;
end;

end.

我用以下命令对此进行了编译:

I compiled this with:

fpc unit1.pp

然后，我编写了以下Delphi程序来链接它:

Then I wrote the following Delphi program to link it:

{$APPTYPE CONSOLE}

{$L 'unit1.o'}

function Test(i: Integer): Integer; cdecl; 
  external name 'UNIT1_TEST$SMALLINT$$SMALLINT';

begin
  Writeln(Test(666));
end.

输出:

27972

请注意，函数名称已修饰.为了找到名称，我使用了objdump:

Note that the function name is decorated. In order to find the name I used objdump:

>objdump -d unit1.o

unit1.o:     file format pe-i386


Disassembly of section .text.n_unit1_test$smallint$$smallint:

00000000 :
   0:   55                      push   %ebp
   1:   89 e5                   mov    %esp,%ebp
   3:   83 ec 04                sub    $0x4,%esp
   6:   0f bf 45 08             movswl 0x8(%ebp),%eax
   a:   6b c0 2a                imul   $0x2a,%eax,%eax
   d:   66 89 45 fc             mov    %ax,-0x4(%ebp)
  11:   66 8b 45 fc             mov    -0x4(%ebp),%ax
  15:   c9                      leave
  16:   c3                      ret
        ...

我使用x86版本的编译器完成了这项工作.我希望它在x64下也可行.

I did this work with x86 versions of the compiler. I expect that it's viable under x64 too.

因此，只要它们足够简单，您就可以链接FPC对象文件.但是，如果您需要任何FPC运行时和标准单元，那么我希望它变得太难了.

So you can indeed link FPC object files, provided that they are simple enough. However, should you need any of the FPC runtime and standard units, then I expect it will become too hard.

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