78 lines
1.9 KiB
NASM
78 lines
1.9 KiB
NASM
; kernLdr_init.asm - This file is a part of NutsOS
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; NutsOS
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; Copyright (C) 2013 Free Software Foundation, Inc.
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; NutsOS is free software; you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation; either version 3 of the License, or
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; (at your option) any later version.
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; NutsOS is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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; You should have received a copy of the GNU General Public License along
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; with NutsOS; If not, see <http://www.gnu.org/licenses/>.
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; Valentin Verdier <valentin.verdier03@gmail.com>
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[BITS 32]
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[SECTION .text]
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global kernLdr_init
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extern kernLdr_main
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kernldr_init:
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; On initialise tous les segments de données pour le mode protégé
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mov ax, 0x10
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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; Segment de pile
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mov ax, 0x18
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mov ss, ax
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mov esp, 0xA0000 ; Pile à 0xA0000
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push eax
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; on vérifie que la ligne a20 est activée
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call check_a20_line
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cmp eax, 0
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je .next ; Si activée, on passe
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call enable_a20_line ; Sinon on l'active
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.next:
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; On appel le fonction principale qui :
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; - calcul la taille de la mémoire utilisable à partir de la liste de plage mémoire communiquée par kernldr_1
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; - charge la partition FAT32 définit
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; - charge KERNEL32 à l'adresse 0x100000, et init à l'adresse 0x28000 depuis le répertoire /boot
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; - construit la structure de passage d'argument
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call kernldr_main
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; On saute vers le kernel
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mov esp, 0xA0000
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jmp 0x08:0x100000
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; Retourne 0xFFFFFFFF si déactivée, 0 si activée
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check_a20_line:
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mov dword [0x500], 0
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mov dword [0x100500], 0xFFFFFFFF
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mov eax, [0x500]
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ret
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enable_a20_line:
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push eax
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in al, 0x92
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test al, 0x02
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jnz .end
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or al, 0x02
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and al, 0xFE
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out 0x92, al
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.end:
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pop eax
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ret
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