Valhalla Legends Archive

OK, I am stumped!

Here is what I have gotten to work

test.c
int _stdcall SendNumber() {
    return 1;
}

test.def
EXPORTS
SendNumber

Then as soon as a add a parameter for the SendNumber function like so:
int _stdcall SendNumber(int inputnum) {
    return inputnum;
}

It definantly does not return the correct number.
I am using GCC command line compiler.

How do you know it is returning the wrong number?  How are you calling it?  Are you trusting the linker to fix up the reference or are you locating it dynamically via GetProcAddress?

You lost me there. I am calling it via VB (unfortunatly my most fluent language). It is returning strange numbers that change each time it is recompiled. And I guess I must be trusting the linker, whatever that is.

What does your declaration function look like for this?

Private Declare Function SendNumber Lib "E:\test.dll" (inputnum As Integer) As Integer

Not sure if this'll change anything, but try:


Private Declare Function SendNumbe Lib "E:\Test.dll" (ByVal InputNum As Long) As Long


Strange enough, it did. Wtf? Works good for now. Here's the next problem: Strings.

Note: All that was needed was ByVal.

Also, when I compile I get this (I changed the function btw):

QuoteWarning: resolving _get_verbyte by linking to _get_verbyte@4
Use --enable-stdcall-fixup to disable these warnings
Use --disable-stdcall-fixup to disable these fixups

It compiled and worked all nicely but, I didn't like seeing errors. So i went into the def file and predefines the linking to @4 like so:
EXPORTS
    get_verbyte@4

Now it cant find dll entry point.

Quote from: FrostWraith on October 18, 2006, 11:36 PM
Strange enough, it did. Wtf? Works good for now. Here's the next problem: Strings.

Note: All that was needed was ByVal.

Also, when I compile I get this (I changed the function btw):

QuoteWarning: resolving _get_verbyte by linking to _get_verbyte@4
Use --enable-stdcall-fixup to disable these warnings
Use --disable-stdcall-fixup to disable these fixups

It compiled and worked all nicely but, I didn't like seeing errors. So i went into the def file and predefines the linking to @4 like so:

Code Select Expand

EXPORTS
    get_verbyte@4

Now it cant find dll entry point.

Public Declare Function GetVersionByte Alias "#4" Lib "Whatever.dll (...) As ...

If I add that, it doesn't work. Does anyone here know how to properly declare an exported fuction in a .def file. I just don't like seeing warnings.

Decorate your exported function signature as


extern "C"


Quote from: FrostWraith on October 19, 2006, 04:09 PM
If I add that, it doesn't work. Does anyone here know how to properly declare an exported fuction in a .def file. I just don't like seeing warnings.

eg:
LIBRARY GUI

EXPORTS
CreateREB
DestroyREB
AppendTextEX
TimeStamper
InsertItem
RemoveItem
GetListViewItemText
GetListViewSelectedItem
GetItemIndex
ModifyItem
ClearListView
SetEditBoxText
GetEditBoxText
AppendEditBoxText
GetIconCode
GetPingCode
MakeTransparent
AddChat
ClearRichEdit
InitImageList
SetRgbBG
CreateLV
__stdcall

OK. I cannot figure out how to pass strings through my C function and return the exact same string. Is "char*" the same data type as "As String" in VB? If it is, do i need to use ByRef to retrieve it in VB? Help me.

So how would I go about sending the parameter with the same data type that is char*?

O have tried:
unsigned char * _stdcall get_version ()
{
    return "1.0.0";
}

Public Declare Function get_version lib "whatever.dll" () As Long

Lookup lstrcpy and lstrlen for this operation

Thank You!

Here was the solution for anyone who ever happens to need help.
char* __stdcall get_version ()
{
    char* s1;
    const char* s2 = "1.0.0";
    char* ptr;

    ptr = strcpy( s1, s2 );
    return ptr;
}

WOW! New strange problem, if I call this function 2 times i crash! Wtf? Should I set everything to null at the end of the function?

Quote from: FrostWraith on October 21, 2006, 12:11 AM
WOW! New strange problem, if I call this function 2 times i crash! Wtf? Should I set everything to null at the end of the function?

It's not really that strange!  Take a look at your code!  You're declaring s1, but you're never allocating memory.  You're overwriting arbitrary memory.  Very, very scary!  You should definitely allocate memory that you're going to memcpy or strcpy to!

That is wrong on so many levels.  I would try something like this:


int __stdcall get_version (char* out)
{
    const char* version = "1.0.0";
    strcpy( out, version);
    return strlen(version);
}



Public Declare Function [Whatever] (ByVal out As String) As Long

Dim buffer As String
Dim len as Long

buffer = Space(255);
len = Whatever(buffer);
buffer = Left(buffer, len);


I'm starting to understand this space thing. So basically what you want to do before you call the get_version function is free up some space that can be over written by the function?  If so, should this standard be used when calling, say, a local VB function?

Also: If the length of the string is static, should I just lower the space to (in this case) 5?

Five is not sufficient.  You're forgetting the terminating null character.

You don't need to preallocate space for calls between functions in VB (as far as I know), but generally you will need to preallocate when calling between different languages.  If you were staying purely in C, you could let the callee allocate it and burden the caller with freeing it.  Strictly speaking, you can do that with VB->C as well, but it's more troublesome.