// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// For the Winscw Emulator only, selects between REF, GCE and non-GCE version of EGL.
// Notes:
//   The default is the non-GCE based version.
//   To use the REF version GCE needs to be enabled. 
//
// To select the GCE version do one of:
// 1. Add a line to the epoc.ini file in \epoc32\data like this:
// symbian_graphics_use_gce ON
// or
// 2. Start epoc.exe with these parameters, (the "--" IS necessary):
// -Dsymbian_graphics_use_gce=ON --
// or
// 3. epoc.exe can be told to switch to a different initialisation file than epoc.ini, with the -M parameter.
// Progress chaining to the real libEGL is logged in epocwind.out.
// 
// To select the REF version do one of the steps above, adding 
// symbian_graphics_use_egl_ref in addition to symbian_graphics_use_gce. 
//
//


#include <emulator.h>
#include <e32svr.h>
#include <u32hal.h>


extern "C" {

#include "egl_stubs.h"

FARPROC vector[MAX_ORDINAL+1];		// 1 additional entry: vector[0] to set the initialised state


void Stop(char* aErrorMessage)
	{
	int err = GetLastError();
	RDebug::Printf("%S, (last error = %i)", aErrorMessage, err);
	_asm int 3;
	}

void fill_vector(HINSTANCE aDll)
	{
	FARPROC address = NULL;
	for (int i=1;i<=MAX_ORDINAL;i++)
		{
		address = GetProcAddress(aDll, (LPCSTR)i);
		if (address == NULL)
			{
			Stop("... has too few exported functions");
			}
		vector[i] = address;
		}

	// There's an additional _E32Dll entry point after last ordinal position.
	// Read it, but no need to store it
	address = GetProcAddress(aDll, (LPCSTR)(MAX_ORDINAL+1));
	if (address == NULL)
		{
		Stop("... has too few exported functions");
		}

	// next position should be empty
	address = GetProcAddress(aDll, (LPCSTR)(MAX_ORDINAL+2));
	if (address != NULL)
		{
		Stop("... has too many exported functions");
		}
	
	// Set initialised
	vector[0] = (FARPROC)1;	
	}

// redirects DLL calls to GCE or non-GCE implementation
void init_vector()
	{
	// ask HAL which configuration to use
	TBool gce = EFalse;
	UserSvr::HalFunction(EHalGroupEmulator, EEmulatorHalBoolProperty,  (TAny*)"symbian_graphics_use_gce",  &gce);
    const char* library = "";
    if (gce)
        {
		// reference EGL is for NGA only
		TBool ref = EFalse;
        UserSvr::HalFunction(EHalGroupEmulator, EEmulatorHalBoolProperty,  (TAny*)"symbian_graphics_use_egl_ref",  &ref);
        library = ref ? "libegl_ref.dll" : "libegl_gce.dll";
        }
	else
		{
		library = "libegl_nongce.dll";
		}

	RDebug::Printf("Redirecting libEGL.dll to \"%s\" ...\n", library);
	
	Emulator::Escape();		// prevent deadlock between EKA2 scheduler and MS kernel
	// try to load selected DLL
	HINSTANCE instance = LoadLibraryA(library);
	Emulator::Reenter();

	if (instance == NULL)
		{
		Stop("... unable to load");
		}
	else
		{
		fill_vector(instance);
		RDebug::Printf("... DLL loaded successfully");
		}
	}

__declspec(naked) void common_dispatch()
	{
	_asm cmp	dword ptr vector,0		// initialised?
	_asm je  	do_init_vector
call_though_vector:
	_asm jmp	[vector+eax*4]

do_init_vector:
	_asm push	eax
	_asm push	ecx
	_asm push	edx
	_asm call	init_vector
	_asm pop	edx
	_asm pop 	ecx
	_asm pop 	eax
	_asm jmp	call_though_vector
	}

}