os-k/kaleid/kernel/mm/gdt.c

//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Desc:         Mapping and checking memory related functions               //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2019 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K 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 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K is distributed in the hope that it will be useful,                   //
//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
//  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 OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <kernel/mm.h>

// The Gdt
GdtEntry_t gdtEntries[5];
GdtPtr_t gdtPtr;

static void SetGdtEntry(int index, uint base, uint limit, uchar access,
                          uchar granularity)
{
    gdtEntries[index].lowBase      = (base & 0xFFFF);
    gdtEntries[index].middleBase   = (base >> 16) & 0xFF;
    gdtEntries[index].highBase     = (base >> 24) & 0xFF;

    gdtEntries[index].lowLimit     = (limit & 0xFFFF);
    gdtEntries[index].granularity  = (limit >> 16) & 0x0F;

    gdtEntries[index].granularity |= granularity & 0xF0;
    gdtEntries[index].access       = access;
}



void MmInitGdt(void)
{
    gdtPtr.limit = (sizeof(GdtEntry_t) * 5) - 1;
    gdtPtr.base  = (uint)(ullong)&gdtEntries;

    SetGdtEntry(0,0,0,0,0);

    /* XXX set TSS register */

    //MmLoadGdt(&gdtPtr);
}