Commit 2149f8c6 authored by rrt's avatar rrt
Browse files

[project @ 2000-11-06 16:43:28 by rrt]

Updated to reflect reality and be a bit more helpful.
parent f3665286
......@@ -11,7 +11,10 @@ section shows you how to make use of this facility.
</Para>
<Para>
<Command>strip</Command> seems not to work reliably on DLLs, so it's probably best not to.
Until recently, <Command>strip</Command> didn't work reliably on DLLs, so you
should test your version with care, or make sure you have the latest
binutils. Unfortunately, we don't know exactly which version of binutils
cured the problem (it was supposedly fixed some years ago).
</Para>
......@@ -27,7 +30,6 @@ command-line, so
</Para>
<Para>
<Screen>
sh$ cat main.hs
module Main where
......@@ -36,20 +38,21 @@ sh$ ghc -o main main.hs
ghc: module version changed to 1; reason: no old .hi file
sh$ strip main.exe
sh$ ls -l main.exe
-rwxr-xr-x 1 544 everyone 6144 May 3 17:11 main.exe*
-rwxr-xr-x 1 544 everyone 4608 May 3 17:11 main.exe*
sh$ ./main
hello, world!
sh$
</Screen>
</Para>
<Para>
will give you a binary as before, but the <Filename>main.exe</Filename> generated will use the Prelude and RTS DLLs instead.
will give you a binary as before, but the <Filename>main.exe</Filename>
generated will use the Prelude and RTS DLLs instead of linking them in
statically.
</Para>
<Para>
6K for a <Literal>"hello, world"</Literal> application---not bad, huh? :-)
4K for a <Literal>"hello, world"</Literal> application---not bad, huh? :-)
</Para>
</Sect1>
......@@ -79,14 +82,14 @@ option on all the Haskell modules that make up your application.
<Para>
<IndexTerm><Primary>Creating a Win32 DLL</Primary></IndexTerm>
<IndexTerm><Primary>--mk-dll</Primary></IndexTerm>
Sealing up your Haskell library inside a DLL is quite straightforward;
Sealing up your Haskell library inside a DLL is straightforward;
compile up the object files that make up the library, and then build
the DLL by issuing the following command:
the DLL by issuing a command of the form:
</Para>
<Para>
<Screen>
ghc --mk-dll -o HSsuper.dll A.o Super.o B.o libmine.a -lgdi32
ghc --mk-dll -o foo.dll bar.o baz.o wibble.a -lfooble
</Screen>
</Para>
......@@ -98,7 +101,9 @@ line.
</Para>
<Para>
To create a `static' DLL, i.e. one that does not depend on the GHC DLLs, compile up your Haskell code using <Option>-static</Option>, and write a <Filename>.def</Filename> file containing the entry points you want to expose (see <XRef LinkEnd="win32-dlls-foreign"> for an example). Then link the DLL adding the <Option>-static</Option> flag, and <Option>-optdll--def=foo.def</Option>, where <Filename>foo.def</Filename> is the name of your <Filename>.def</Filename> file.
To create a `static' DLL, i.e. one that does not depend on the GHC DLLs,
use the <Option>-static</Option> when compiling up your Haskell code and
building the DLL.
</Para>
<Para>
......@@ -112,15 +117,22 @@ A couple of things to notice:
<Para>
Since DLLs correspond to packages (see <XRef LinkEnd="packages">) you need
to use <Option>-package-name dll-name</Option> when compiling modules that
belong to a DLL. If you don't, Haskell code that calls entry points in that
DLL will do so incorrectly, and a crash will result.
belong to a DLL if you're going to call them from Haskell. Otherwise, Haskell
code that calls entry points in that DLL will do so incorrectly, and crash.
For similar reasons, you can only compile a single module tree into a DLL,
as <Function>startupHaskell</Function> needs to be able to call its
initialisation function, and only takes one such argument (see <XRef
LinkEnd="win32-dlls-foreign">). Hence the modules
you compile into a DLL must have a common root.
</Para>
</ListItem>
<ListItem>
<Para>
By default, the entry points of all the object files will
be exported from the DLL when using <Option>--mk-dll</Option>. Should you want to constrain this, you can specify the <Emphasis>module definition file</Emphasis> to use on the command line as follows:
By default, the entry points of all the object files will be exported from
the DLL when using <Option>--mk-dll</Option>. Should you want to constrain
this, you can specify the <Emphasis>module definition file</Emphasis> to use
on the command line as follows:
<Screen>
ghc --mk-dll -o .... -optdll--def -optdllMyDef.def
......@@ -150,9 +162,10 @@ name of the DLL, as follows:
DLL: HScool.dll ==&#62; import lib: libHScool_imp.a
</ProgramListing>
The naming scheme may look a bit weird, but it has the purpose of
allowing the co-existence of import libraries with ordinary static
libraries (e.g., <Filename>libHSfoo.a</Filename> and <Filename>libHSfoo&lowbar;imp.a</Filename>.
The naming scheme may look a bit weird, but it has the purpose of allowing
the co-existence of import libraries with ordinary static libraries (e.g.,
<Filename>libHSfoo.a</Filename> and
<Filename>libHSfoo&lowbar;imp.a</Filename>.
Additionally, when the compiler driver is linking in non-static mode, it
will rewrite occurrence of <Option>-lHSfoo</Option> on the command line to
......@@ -185,7 +198,8 @@ combine this with DLL building, so here's an example:
<ListItem>
<Para>
Use <Literal>foreign export</Literal> declarations to export the Haskell functions you want to call from the outside. For example,
Use <Literal>foreign export</Literal> declarations to export the Haskell
functions you want to call from the outside. For example,
<ProgramListing>
module Adder where
......@@ -212,15 +226,17 @@ This will produce two files, adder.o and adder_stub.o
<ListItem>
<Para>
compile up a <Function>DllMain()</Function> that starts up the Haskell RTS---a possible implementation is:
compile up a <Function>DllMain()</Function> that starts up the Haskell
RTS---a possible implementation is:
<ProgramListing>
#include &lt;windows.h&gt;
#include &lt;Rts.h&gt;
extern void startupHaskell(int , char** );
static char* args[] = { "ghcDll" };
EXTFUN(__init_Adder);
static char* args[] = { "ghcDll", NULL };
/* N.B. argv arrays must end with NULL */
BOOL
STDCALL
DllMain
......@@ -231,13 +247,17 @@ DllMain
{
if (reason == DLL_PROCESS_ATTACH) {
/* By now, the RTS DLL should have been hoisted in, but we need to start it up. */
startupHaskell(1, args);
startupHaskell(1, args, __init_Adder);
return TRUE;
}
return TRUE;
}
</ProgramListing>
Here, <Literal>Adder</Literal> is the name of the root module in the module
tree (as mentioned above, there must be a single root module, and hence a
single module tree in the DLL).
Compile this up:
<Screen>
......@@ -259,16 +279,24 @@ ghc --mk-dll -o adder.dll adder.o adder_stub.o dllMain.o
<ListItem>
<Para>
Start using <Function>adder</Function> from VBA---here's how I would <Constant>Declare</Constant> it:
Start using <Function>adder</Function> from VBA---here's how I would
<Constant>Declare</Constant> it:
<ProgramListing>
Private Declare adder Lib "adder.dll" Alias "adder@8"
Private Declare Function adder Lib "adder.dll" Alias "adder@8"
(ByVal x As Long, ByVal y As Long) As Long
</ProgramListing>
Since this Haskell DLL depends on a couple of the DLLs that come with GHC,
make sure that they are in scope/visible.
</Para>
<Para>
Building statically linked DLLs is the same as in the previous section: it
suffices to add <Option>-static</Option> to the commands used to compile up
the Haskell source and build the DLL.
</Para>
</ListItem>
</ItemizedList>
......
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