kernel2/include/gdt.h

   1 /*
   2     meinOS - A unix-like x86 microkernel operating system
   3     Copyright (C) 2008  Janosch Gräf <janosch.graef@gmx.net>
   4
   5     This program is free software: you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation, either version 3 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #ifndef _GDT_H_
  20 #define _GDT_H_
  21
  22 #include <sys/types.h>
  23 #include <stdint.h>
  24
  25 #define GDT_CODESEG 0x0A
  26 #define GDT_DATASEG 0x02
  27 #define GDT_TSS 0x09
  28 #define GDT_PRESENT 0x80
  29 #define GDT_SEGMENT 0x10
  30
  31 #define GDT_TSSDESC 8
  32
  33 #define GDT_MAXDESC 64
  34
  35 #define IDX2SEL(idx,priv) (((idx)<<3)|(priv))
  36
  37 typedef enum {
  38   PRIV_KERNEL = 0,
  39   PRIV_USER = 3
  40 } priv_t;
  41
  42 /*typedef struct {
  43   unsigned limit0_15:16;
  44   unsigned base0_15:16;
  45   unsigned base16_23:8;
  46   unsigned accessed:1;
  47   unsigned int rw:1;
  48   enum {
  49     GDT_UP = 0,
  50     GDT_DOWN = 1
  51   } dc:1;
  52   enum {
  53     GDT_DATA = 0,
  54     GDT_CODE = 1
  55   } type:1;
  56   unsigned notsystem:1;
  57   priv_t priv:2;
  58   unsigned present:1;
  59   unsigned zero:2;
  60   enum {
  61     GDT_16BIT = 0,
  62     GDT_32BIT = 1,
  63   } size:1;
  64   gran_t granular:1;
  65   unsigned limit16_19:4;
  66   unsigned base24_31:8;
  67 } __attribute__ ((packed)) gdtdesc_t;*/
  68 typedef struct {
  69   uint16_t size0_15;
  70   uint16_t base0_15;
  71   uint8_t base16_23;
  72   uint8_t access;
  73   uint8_t flags;
  74   uint8_t base24_31;
  75 } __attribute__ ((packed)) gdtdesc_t;
  76
  77 typedef struct {
  78   uint16_t size;
  79   uint32_t offset;
  80 } __attribute__ ((packed)) gdtsel_t;
  81
  82 typedef struct {
  83   priv_t priv:2;
  84   unsigned ti:1;
  85   unsigned index:13;
  86 } __attribute__ ((packed)) selector_t;
  87
  88 typedef gdtdesc_t* gdt_t;
  89
  90 //gdt_t gdt;
  91 gdtdesc_t gdt[GDT_MAXDESC];
  92
  93 int gdt_init();
  94 void gdt_set_descriptor(int segment,size_t size,void *base,int access,priv_t priv);
  95
  96 #endif