/* 
 * Copyright 2010 Stefan Lankes, Chair for Operating Systems,
 *                               RWTH Aachen University
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This file is part of MetalSVM.
 *
 */

#ifndef __ARCH_TASKS__
#define __ARCH_TASKS__

#include <metalsvm/stddef.h>
#include <metalsvm/tasks_types.h>

void NORETURN leave_task(void);

inline static int create_default_frame(task_t* task, entry_point_t ep, void* arg)
{
	unsigned int* top = (unsigned int*) task->top;
	unsigned int* esp;
	unsigned int* ebp;

	*top = 0xDEADBEAF; 			/* dead-end */
	ebp = top;
	top--;
	*top = (unsigned int) arg; 		/* argument of the function ep */
	top--;
	*top = (unsigned int) leave_task; 	/* exit function */
	top--;
	*top = (unsigned int) ep;		/* entry point */
	top--;
	*top = 0x202;				/* EFLAGS */
	esp = top;
	top--;
	*top = 0x00;				/* EAX */
	top--;
	*top = 0x00;				/* ECX */
	top--;
	*top = 0x00;				/* EDX */
	top--;
	*top = 0x00;				/* EBX */
	top--;
	*top = (unsigned int) esp;		/* ESP */
	top--;
	*top = (unsigned int) ebp; 		/* EBP */
	top --;
	*top = 0x00;				/* ESI */
	top --;
	*top = 0x00;				/* EDI */
	top --;
	*top = 0x10;				/* DS */
	top--;
	*top = 0x10;				/* ES */
	top--;
	*top = 0x10;				/* FS */
	top--;
	*top = 0x10;				/* GS */

	task->top = (unsigned char*) top;

	return 0;
}

#endif