/* 
 * 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_GDT_H__
#define __ARCH_GDT_H__

#include <metalsvm/stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

#define GDT_FLAG_DATASEG        0x02
#define GDT_FLAG_CODESEG        0x0a
#define GDT_FLAG_TSS            0x09
#define GDT_FLAG_TSS_BUSY	0x02

#define GDT_FLAG_SEGMENT        0x10
#define GDT_FLAG_RING0          0x00
#define GDT_FLAG_RING1          0x20
#define GDT_FLAG_RING2          0x40
#define GDT_FLAG_RING3          0x60
#define GDT_FLAG_PRESENT        0x80

#define GDT_FLAG_4K_GRAN        0x80
#define GDT_FLAG_32_BIT         0x40

/* Defines a GDT entry */
typedef struct {
	unsigned short limit_low;
	unsigned short base_low;
	unsigned char base_middle;
	unsigned char access;
	unsigned char granularity;
	unsigned char base_high;
} __attribute__ ((packed)) gdt_entry_t;

typedef struct {
	unsigned short limit;
	unsigned int base;
} __attribute__ ((packed)) gdt_ptr_t;

#define GDT_ENTRIES     (5+MAX_TASKS)
#if GDT_ENTRIES > 8192
#error Too many GDT entries!
#endif

//extern gdt_entry_t	gdt[GDT_ENTRIES];

void gdt_install(void);

#ifdef __cplusplus
}
#endif

#endif