From 453c3d130b34e317fa8368eeff104ccf219a3088 Mon Sep 17 00:00:00 2001 From: VinceAle7082 Date: Wed, 24 Jul 2024 11:23:05 +0200 Subject: [PATCH] Many things pt.2 Now the bootloader (/src/boot.asm) has a FAT12 driver that searches the KERNEL.BIN file and loads it. Now the kernel has something in it, it just prints a Hello World message. --- Makefile | 4 +- src/bootloader/boot.asm | 278 ++++++++++++++++++++++++++++++---------- src/kernel/kernel.asm | 56 ++++++++ 3 files changed, 266 insertions(+), 72 deletions(-) diff --git a/Makefile b/Makefile index 49d75cd..b76f2f2 100644 --- a/Makefile +++ b/Makefile @@ -42,4 +42,6 @@ always: #Clean clean: - rm -rf $(BUILD_DIR)/* \ No newline at end of file + rm -rf $(BUILD_DIR)/* + +#Strumenti \ No newline at end of file diff --git a/src/bootloader/boot.asm b/src/bootloader/boot.asm index e229366..1ad257c 100644 --- a/src/bootloader/boot.asm +++ b/src/bootloader/boot.asm @@ -8,19 +8,19 @@ bits 16 jmp short start nop -bdb_oem: db 'MSWIN4.1' -bdb_bytes_per_sector: dw 512 -bdb_sectors_per_cluster: db 1 -bdb_reserved_sectors: dw 1 -bdb_fat_count: db 2 -bdb_dir_entries_count: dw 0E0h -bdb_total_sectors: dw 2880 -bdb_media_descriptor_type: db 0F0h -bdb_sectors_per_fat: dw 9 -bdb_sectors_per_track: dw 18 -bdb_heads: dw 2 -bdb_hidden_sectors: dd 0 -bdb_large_sector_count: dd 0 +oem: db 'MSWIN4.1' +bytes_per_sector: dw 512 +sectors_per_cluster: db 1 +reserved_sectors: dw 1 +fat_count: db 2 +dir_entries_count: dw 0E0h +total_sectors: dw 2880 +media_descriptor_type: db 0F0h +sectors_per_fat: dw 9 +sectors_per_track: dw 18 +heads: dw 2 +hidden_sectors: dd 0 +large_sector_count: dd 0 ebr_drive_number: db 0 db 0 @@ -29,71 +29,158 @@ ebr_volume_id: db 12h, 34h, 56h, 78h ebr_volume_label: db 'XanvicOS ' ebr_system_id: db 'FAT12 ' -;Codice +;Codice del bootloader start: - jmp main + ;Inizializza segmenti di dati -puts: - push si - push ax - push bx - -.loop: - lodsb - or al, al - jz .fine - - mov ah, 0x0E - mov bh, 0 - int 0x10 - - jmp .loop - -.fine: - pop bx - pop ax - pop si - ret - -main: mov ax, 0 mov ds, ax mov es, ax + ;Iniializza gli stack + mov ss, ax mov sp, 0x7C00 - mov si, msg_helloworld +.dopo: + + ;Mostra il messaggio di caricamento + + mov si, msg_caricamento call puts ;Legge cose dal floppy + mov [ebr_drive_number], dl - mov ax, 1 - mov cl, 1 - mov bx, 0x7E00 + ;Legge i parametri del disco + + push es + mov ah, 08h + int 13h + jc errore_floppy + pop es + + and cl, 0x3F + xor ch, ch + mov [sectors_per_track], cx + + inc dh + mov [heads], dh + + ;Calcola l'indirizzo LBA della root del filesystem FAT12 + + mov ax, [sectors_per_fat] + mov bl, [fat_count] + xor bh, bh + mul bx + add ax, [reserved_sectors] + push ax + + ;Calcola il peso della root + + mov ax, [sectors_per_fat] + shl ax, 5 + xor dx, dx + div word [bytes_per_sector] + + test dx, dx + jz .root_dopo + inc ax + +.root_dopo: + ;Legge la root + mov cl, al + pop ax + mov dl, [ebr_drive_number] + mov bx, buffer call lettura_disco - cli - hlt + ;Cerca il kernel + xor bx, bx + mov di, buffer -;Errori +.cerca_kernel: + mov si, file_kernel_bin + mov cx, 11 + push di + repe cmpsb + pop di + je .kernel_trovato -errore_floppy: - mov si, msg_errore_lettura + add di, 32 + inc bx + cmp bx, [dir_entries_count] + jl .cerca_kernel + + ;Kernel non trovato + jmp errore_kernel_non_trovato + +.kernel_trovato: + mov si, msg_kernel_trovato call puts + + mov ax, [di + 26] + mov [kernel_cluster], ax + + mov ax, [reserved_sectors] + mov bx, buffer + mov cl, [sectors_per_fat] + mov dl, [ebr_drive_number] + call lettura_disco + + mov bx, KERNEL_LOAD_SEGMENT + mov es, bx + mov bx, KERNEL_LOAD_OFFSET + +.carica_kernel: + mov ax, [kernel_cluster] + add ax, 31 + + mov cl, 1 + mov dl, [ebr_drive_number] + call lettura_disco + + add bx, [bytes_per_sector] + + mov ax, [kernel_cluster] + mov cx, 3 + mul cx + mov cx, 2 + div cx + + mov si, buffer + add si, ax + mov ax, [ds:si] + + or dx, dx + jz .pari + +.dispari: + shr ax, 4 + jmp .prossimo_cluster + +.pari: + and ax, 0x0FFF + +.prossimo_cluster: + cmp ax, 0x0FF8 + jae .fine_lettura + + mov [kernel_cluster], ax + jmp .carica_kernel + +.fine_lettura: + mov dl, [ebr_drive_number] + + mov ax, KERNEL_LOAD_SEGMENT + mov ds, ax + mov es, ax + + jmp KERNEL_LOAD_SEGMENT:KERNEL_LOAD_OFFSET jmp premi_per_riavviare -premi_per_riavviare: - mov ah, 0 - int 16h - jmp 0FFFFh:0 - -.halt: - cli - hlt - ;Trasforma/Converte un indirizzo LBA in uno CHS lba_to_chs: @@ -101,13 +188,13 @@ lba_to_chs: push dx xor dx, dx - div word [bdb_sectors_per_track] + div word [sectors_per_track] inc dx mov cx, dx xor dx, dx - div word [bdb_heads] + div word [heads] mov dh, dl mov ch, al @@ -123,11 +210,7 @@ lba_to_chs: ;Legge i settori da un disco lettura_disco: -; push ax -; push bx push cx -; push dx -; push di call lba_to_chs pop ax @@ -155,11 +238,6 @@ lettura_disco: .fine: popa -; pop di -; pop dx -; pop cx -; pop bx -; pop ax ret disk_reset: @@ -171,12 +249,70 @@ disk_reset: popa ret -;Mostra una stringa sullo schermo +puts: + ;Salva i registri + push si + push ax + push bx + +.loop: + lodsb + or al, al ; verify if next character is n + jz .fine + + mov ah, 0x0E ; call bios interrupt + mov bh, 0 ; set page number to 0 + int 0x10 + + jmp .loop + +.fine: + pop bx + pop ax + pop si + ret + +;Mostra delle stringhe sullo schermo + +msg_caricamento: + db 'Caricamento...', ENDL, 0 -msg_helloworld: - db 'Hello World!', ENDL, 0 msg_errore_lettura: - db 'Errore nella lettura del disco!' + db 'Errore del disco', ENDL, 0 + +msg_kernel_non_trovato: + db 'Kernel non trovato', ENDL, 0 + +msg_kernel_trovato: + db 'Kernel trovato', ENDL, 0 + +;Errori + +errore_floppy: + mov si, msg_errore_lettura + call puts + jmp premi_per_riavviare + +errore_kernel_non_trovato: + mov si, msg_kernel_non_trovato + call puts + jmp premi_per_riavviare + +;Variabili + +file_kernel_bin: db 'KERNEL BIN' +kernel_cluster: dw 0 +KERNEL_LOAD_SEGMENT equ 0x2000 +KERNEL_LOAD_OFFSET equ 0 + +;Cose che non so dove mettere + +premi_per_riavviare: + mov ah, 0 + int 16h + jmp 0FFFFh:0 times 510-($-$$) db 0 dw 0AA55h + +buffer: diff --git a/src/kernel/kernel.asm b/src/kernel/kernel.asm index e69de29..0e5d752 100644 --- a/src/kernel/kernel.asm +++ b/src/kernel/kernel.asm @@ -0,0 +1,56 @@ +org 0x0 +bits 16 + + +%define ENDL 0x0D, 0x0A + +;Codice del kernel +start: + mov si, msg_helloworld + call puts + call premi_per_riavviare + +.halt: + cli + hlt + +puts: + ; save registers we will modify + push si + push ax + push bx + +.loop: + lodsb + or al, al + jz .fine + + mov ah, 0x0E + mov bh, 0 + int 0x10 + + jmp .loop + +.fine: + pop bx + pop ax + pop si + ret + +;Stringhe +msg_helloworld: + db 'Hello World dal kernel!', ENDL, 0 + +msg_premi_per_riavviare: + db 'Premi un tasto per riavviare...', ENDL, 0 +;Errori + +;Variabili + +;Cose che non so dove mettere +premi_per_riavviare: + mov si, msg_premi_per_riavviare + call puts + mov ah, 0 + int 16h + jmp 0FFFFh:0 \ No newline at end of file