hello i try load dll into memory and play sound file from resources (Delphi2009). In this example i load dll from HDD to memory (i plan to load dll from resources to memory) but i got an error after Button1Click
First chance exception at $76E2C41F. Exception class EAccessViolation with message 'Access violation at address 00000000. Read of address 00000000'. Process DemoApp.exe (3020)
Sound doesn't play at all :/
some of code i used from here: http://www.cyberforum.ru/blogs/14360/blog1682.html#a_codemodez but i couldn't compile it due to custom units strUtilz, MemModuleUnicode
BTMemoryModule v0.0.41 includes BTMemoryModule and also examples
http://code.google.com/p/memorymodule/downloads/list
BTMemoryModule v.1 (old probably) (with BTMemoryModule + BTMemoryModuleUnicode)
http://www.delphibasics.info/home/delphibasicssnippets/btmemorymodule
unit Main;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, BTMemoryModule, StdCtrls, xpman;
const // Constants :::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
_s = '';
_n=#13#10; // line break
ver = '1.0 '; // Articles
tit = 'Bass Memory App' + ver; // title - the name of the application
msgYN=$04; msgERR=$10; msgINF=$40; // <-type codes posts
res1='dll'; // resource name with dllkoy
res2='snd'; // name of the resource with sound
type // TYPES :::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::::::::
MemRes = record // structure for the projection of the resource in memory
p: pointer; // pointer to the memory
sz: int64; // size (length)
rd: cardinal; // hResData
ri: cardinal; // hResInfo
end;
type
TBASS_ChannelPlay = function (handle: cardinal; restart: bool): bool; stdcall;
TBASS_StreamCreateFile = function (mem: bool; f: Pointer; offset, length: int64; flags: cardinal): cardinal; stdcall;
TBASS_StreamFree = function (handle: cardinal): bool; stdcall;
TBASS_Init = function (device: integer; freq, flags: cardinal; win: cardinal; clsid: pGUID): bool; stdcall;
TBASS_Free = function: bool; stdcall;
TForm1 = class(TForm)
BtnFileCAll: TButton;
BtnMemCall: TButton;
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
mp_DllData : Pointer;
m_DllDataSize : Integer;
mp_MemoryModule: PBTMemoryModule;
//m_DllHandle: Cardinal;
m_BASS_ChannelPlay: TBASS_ChannelPlay;
m_BASS_StreamCreateFile: TBASS_StreamCreateFile;
//m_BASS_StreamFree: TBASS_StreamFree;
m_BASS_Init: TBASS_Init;
//m_BASS_Free: TBASS_Free;
public
{ Public declarations }
end;
var
Form1: TForm1;
wnd: cardinal; // window handle
ss: cardinal; // handle audio stream
snd: MemRes; // pointer to the audio file in memory
dll: MemRes; // pointer to memory dllku
bass: Pointer; // structure projection dll in memory
stp: word; // execution step (for debug)
st: boolean; // status of the audio stream
th: cardinal; // handle the flow of replacement buttons
ti: cardinal; // id flow
ms : TMemoryStream;
rs : TResourceStream;
implementation
{$R *.dfm}
{$R BassMem.RES} // snd CookieJarLoop.ogg RCData
function Res2Mem(hInst:cardinal;res:string;rtype:pChar):MemRes;
begin
result.p:=nil;
result.ri:=FindResource(hInst,pchar(res),rtype);
if result.ri=0 then exit;
result.sz:=SizeOfResource(hInst,result.ri);
if result.sz=0 then exit;
result.rd:=LoadResource(hInst,result.ri);
if result.rd=0 then exit;
result.p:=LockResource(result.rd);
end;
procedure TForm1.FormCreate(Sender: TObject);
var
MemoryStream: TMemoryStream;
begin
Position := poScreenCenter;
MemoryStream := TMemoryStream.Create;
MemoryStream.LoadFromFile('bass.dll');
MemoryStream.Position := 0;
m_DllDataSize := MemoryStream.Size;
mp_DllData := GetMemory(m_DllDataSize);
MemoryStream.Read(mp_DllData^, m_DllDataSize);
MemoryStream.Free;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FreeMemory(mp_DllData);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
mp_MemoryModule := BTMemoryLoadLibary(mp_DllData, m_DllDataSize);
try
if mp_MemoryModule = nil then showmessage('err1');
@m_BASS_Init := BTMemoryGetProcAddress(mp_MemoryModule, 'BASS_Init');
if @m_BASS_Init = nil then showmessage('err2');
@m_BASS_ChannelPlay := BTMemoryGetProcAddress(mp_MemoryModule, 'BASS_ChannelPlay');
if @m_BASS_ChannelPlay = nil then showmessage('err3');
m_BASS_Init(-1, 44100, 0, Handle, nil);
snd:=Res2Mem(hInstance, res2 ,RT_RCDATA);
ss:=m_BASS_StreamCreateFile(true,snd.p,0,snd.sz,4{=BASS_SAMPLE_LOOP});
if ss=0 then showmessage('err ss=0');
m_BASS_ChannelPlay(ss, false);
except
Showmessage('An error occoured while loading the dll: ' + BTMemoryGetLastError);
end;
if mp_MemoryModule <> nil then BTMemoryFreeLibrary(mp_MemoryModule);
end;
end.
You do not initialise m_BASS_StreamCreateFile. Consequently it has the value nil when you call it. Which explains the error message.
You need to add a call to BTMemoryGetProcAddress to initialise m_BASS_StreamCreateFile.
@m_BASS_StreamCreateFile := BTMemoryGetProcAddress(mp_MemoryModule,
'BASS_StreamCreateFile');
if @m_BASS_StreamCreateFile = nil then ....
This would have been simple enough to discover had you run the code under the debugger. The exception would have been trapped by the debugger and the call stack will have led to the call of m_BASS_StreamCreateFile. You could then have inspected its value to discover that it was nil.