mirror of
https://gitlab.os-k.eu/os-k-team/os-k.git
synced 2023-08-25 14:03:10 +02:00
178 lines
9.0 KiB
PHP
178 lines
9.0 KiB
PHP
;=----------------------------------------------------------------------------=;
|
|
; GNU GPL OS/K ;
|
|
; ;
|
|
; Desc: Bootsector for OS/K INCLUDED FUNCTIONS ;
|
|
; (x86_64 architecture only) ;
|
|
; ;
|
|
; ;
|
|
; 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/>. ;
|
|
;=----------------------------------------------------------------------------=;
|
|
|
|
[BITS 16]
|
|
|
|
read_clusters:
|
|
;---------------------------------------------------;
|
|
; Read file clusters, starting at the given cluster,;
|
|
; expects FAT to be loaded into the disk buffer. ;
|
|
; Please note that this may allocate up to 128KB ;
|
|
; of ram. ;
|
|
; ;
|
|
; Expects: AX = Starting cluster ;
|
|
; ES:DI = Location to load clusters ;
|
|
; ;
|
|
; Returns: None ;
|
|
; ;
|
|
;---------------------------------------------------;
|
|
pusha
|
|
push es
|
|
.cluster_loop:
|
|
xor bh, bh
|
|
xor dx, dx
|
|
push ax ; Get the cluster start = (cluster - 2) * sectorsPerCluster + UserData
|
|
sub ax, 2 ; Subtract 2
|
|
mov bl, byte [sectorsPerCluster] ; Sectors per cluster is a byte value
|
|
mul bx ; multiply (cluster - 2) * sectorsPerCluster
|
|
add ax, word [UserData] ; add the UserData
|
|
xor ch, ch
|
|
mov cl, byte [sectorsPerCluster] ; Sectors to read
|
|
call read_sectors ; Read the sectors
|
|
pop ax ; Current cluster number
|
|
xor dx, dx
|
|
;; Calculate next sector for FAT16 (cluster * 2)
|
|
mov bx, 2 ; Multiply the cluster by two (cluster is in ax)
|
|
mul bx
|
|
;; Load sector in RAM
|
|
push ds
|
|
push si
|
|
mov si, BUFFER_SEG
|
|
mov ds, si ; Temporarly set ds:si to the FAT buffer
|
|
mov si, BUFFER_OFF
|
|
add si, ax ; Point to the next cluster in the FAT entry
|
|
mov ax, word [ds:si] ; Load ax to the next cluster in FAT
|
|
pop si
|
|
pop ds
|
|
;; Next
|
|
cmp ax, 0xfff8 ; Check if we are at the end of the file?
|
|
jae .done
|
|
add di, 512 ; Add to the pointer offset
|
|
jnc .cluster_loop
|
|
;; Correct the buffer because an error will occur if the buffer in memory
|
|
mov dx, es ; overlaps a 64k page boundry, when di overflows
|
|
add dh, 0x10 ; it will trigger the carry flag, so correct
|
|
mov es, dx ; extra segment by 0x1000
|
|
jmp .cluster_loop ; Load the next file cluster
|
|
.done:
|
|
pop es
|
|
popa
|
|
ret
|
|
|
|
|
|
read_sectors:
|
|
;---------------------------------------------------;
|
|
; Read sectors starting at a given sector by ;
|
|
; the given times and load into a buffer. Please ;
|
|
; note that this may allocate up to 128KB of ram. ;
|
|
; ;
|
|
; Expects: AX = Starting sector ;
|
|
; CX = Number of sectors to read ;
|
|
; ES:DI = Location to load sectors ;
|
|
; ;
|
|
; Returns: None ;
|
|
; ;
|
|
;---------------------------------------------------;
|
|
pusha
|
|
push es
|
|
mov bx, di ; Convert es:di to es:bx for int 13h
|
|
.sector_loop:
|
|
push ax
|
|
push cx
|
|
xor dx, dx
|
|
div word [sectorsPerTrack] ; Divide the lba (value in ax) by sectorsPerTrack
|
|
mov cx, dx ; Save the absolute sector value
|
|
inc cx
|
|
xor dx, dx ; Divide by the number of heads
|
|
div word [heads] ; to get absolute head and track values
|
|
mov dh, dl ; Move the absolute head into dh
|
|
mov ch, al ; Low 8 bits of absolute track
|
|
shl ah, 1 ; High 2 bits of absolute track
|
|
shl ah, 1
|
|
shl ah, 1
|
|
shl ah, 1
|
|
shl ah, 1
|
|
shl ah, 1
|
|
or cl, ah ; Now cx is set with respective track and sector numbers
|
|
mov dl, byte [Bootdrv] ; Set correct Bootdrv for int 13h
|
|
mov di, 21 ; Try five times to read the sector because I love 21
|
|
.attempt_read:
|
|
mov ax, 0x0201 ; Read Sectors func of int 13h, read one sector
|
|
int 0x13 ; Call int 13h (BIOS disk I/O)
|
|
jnc .read_ok ; If no carry set, the sector has been read
|
|
xor ah, ah ; Reset Bootdrv func of int 13h
|
|
int 0x13 ; Call int 13h (BIOS disk I/O)
|
|
dec di ; Decrease read attempt counter
|
|
jnz .attempt_read ; Try to read the sector again
|
|
mov si, DiskError ; Error reading the disk :/
|
|
call print
|
|
jmp reboot
|
|
.read_ok:
|
|
pop cx
|
|
pop ax
|
|
inc ax ; Increase the next sector to read
|
|
add bx, word [bytesPerSector] ; Add to the buffer address for the next sector
|
|
jnc .next_sector
|
|
;; Fixing buffer because an error will occur if the buffer in memory
|
|
mov dx, es ; overlaps a 64k page boundry, when bx overflows
|
|
add dh, 0x10 ; it will trigger the carry flag, so correct
|
|
mov es, dx ; es segment by 0x1000
|
|
.next_sector:
|
|
loop .sector_loop
|
|
pop es
|
|
popa
|
|
ret
|
|
|
|
print:
|
|
;---------------------------------------------------;
|
|
; Print out a simple string. ;
|
|
; ;
|
|
; Expects: DS:SI = String to print ;
|
|
; ;
|
|
; Returns: None ;
|
|
; ;
|
|
;---------------------------------------------------;
|
|
lodsb ; Load byte from ds:si to al
|
|
or al, al ; If al is empty stop looping
|
|
jz .done ; Done looping and return
|
|
mov ah, 0x0e ; Teletype output
|
|
int 0x10 ; Video interupt
|
|
jmp print ; Loop untill string is null
|
|
.done:
|
|
ret
|
|
|
|
reboot:
|
|
xor ax, ax
|
|
int 0x16 ; Get a single keypress
|
|
mov ah, 0x0e ; Teletype output
|
|
mov al, 0x0d ; Carriage return
|
|
int 0x10 ; Video interupt
|
|
mov al, 0x0a ; Line feed
|
|
int 0x10 ; Video interupt
|
|
mov al, 0x0a ; Line feed
|
|
int 0x10 ; Video interupt
|
|
xor ax, ax
|
|
int 0x19 ; Reboot the system
|