idt.c

一个操作系统的源代码

/** idt.c
 **
 ** Original Author: Kasper Verdich Lund
 ** Date: 10/11/99
 **
 ** Description:
 ** Interrupt Descriptor Table functions
 **
 ** This program is free software, you can redistribute it and/or
 ** modify it under the terms of the GNU General Public License
 ** as published by the Free Software Foundation; either version
 ** 2 of the License, or (at your option) any later version.
 **
 ** This program is distributed in the hope that it will be
 ** useful, but WITHOUT ANY WARRANTY; without even the implied
 ** warranty or MERCHANTABILITY or FITNESS FOR A PARTICULAR
 ** PURPOSE.  See the GNU General Public License for more
 ** details.
 **
 ** You should have received a copy of the GNU General Public
 ** License along with this program; if not, write to the
 ** Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 ** Boston, MA 02111-1307 USA
 **
 *********************************************************Apostle OS**/

#include <idt.h>
#include <types.h>
#include <io.h>
#include <gdt.h>
#include <string.h>

gate *IDT = (gate *)(GDT_SIZE * sizeof(descriptor));

void setupIDT(void)
{
  dword IDTR[2];

  memset(IDT, 0, IDT_SIZE * sizeof(gate));
  IDTR[0] = ((IDT_SIZE * sizeof(gate)) - 1) << 16;
  IDTR[1] = (dword)IDT;
  /* load the IDTR - it's only 48-bits and therefore the 
   * two first bytes are not used */
  __asm__("lidt (%0)" : : "r" (((byte *)IDTR) + 2));  
}

void interruptIDT(gate *g, word selector, dword offset, byte dpl)
{
  g->offset0_15 = offset;
  g->offset16_31 = offset >> 16;
  g->selector = selector;
  g->zero = 0;
  g->p = 1;
  g->dpl = dpl;
  g->type = 0xE; /* assuming 32-bit interrupt gate */ 
}

void trapIDT(gate *g, word selector, dword offset, byte dpl)
{
  g->offset0_15 = offset;
  g->offset16_31 = offset >> 16;
  g->selector = selector;
  g->zero = 0;
  g->p = 1;
  g->dpl = dpl;
  g->type = 0xF; /* assuming 32-bit trap gate */ 
}

void taskIDT(gate *g, word selector, byte dpl)
{
  g->offset0_15 = 0;
  g->offset16_31 = 0;
  g->selector = selector;
  g->zero = 0;
  g->p = 1;
  g->dpl = dpl;
  g->type = 5;
}