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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;; Miguel's FoolOS Helper Functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;disk_load_16
;
[bits 16]
STR_ERROR:
db "Disk Read Error",0
STR_SPACE:
db " ",0
STR_OK:
db "Kernel Loaded",0
STR_PROGRESS:
db ".",0
bpbSectorsPerTrack:
dw 18
bpbHeadsPerCylinder:
dw 2
LBA:
dw 10 ; current lba
disk_load_16:
; check if LBA is supported
mov ah,0x41
mov bx,0x55aa
int 0x13
jnc disk_load_lba
jmp disk_load_chs
;#######################
disk_load_lba:
pusha
mov bx,0x1800 ;target es:bx
mov es,bx
mov bx,0
next_sectors_lba:
jmp skip_debug_lba
;show es - target
pusha
mov bx,es
;mov al,bh
;call print_hex_byte
;mov al,bl
;call print_hex_byte
mov bx,[LBA]
mov al,bh
call print_hex_byte
mov al,bl
call print_hex_byte
popa
;--
skip_debug_lba:
mov [lba_addr_sector],es
mov ax,[LBA]
mov [lba_first_sector],ax
mov dl,[BOOT_DRIVE]
mov ah,0x42
mov bx,0
mov ds,bx
lea si,[lba_adr]
int 0x13
jc disk_read_error
mov bx,es
add bx,0x0800
mov ax,[LBA]
add ax,64 ; 64 sectors = 0x2000*4 bytes
mov [LBA],ax
cmp bx,0x9000
je disk_load_finish
mov es,bx ;next target es:bx
mov bx,0
jmp next_sectors_lba
;#######################
disk_load_chs:
pusha
; get boot drive geometry
mov ah,8
mov dl,[BOOT_DRIVE]
int 0x13
add dh,1
and cl,0x3f
mov [bpbSectorsPerTrack],cl
mov [bpbHeadsPerCylinder],dh
;
;show geometry
mov al,dh
call print_hex_byte
mov bx, STR_SPACE
call print_string
mov al,cl
call print_hex_byte
call print_nextline
popa
;
pusha
mov bx,0x1800 ;target es:bx
mov es,bx
mov bx,0
next_sectors_chs:
;jmp skip_debug
pusha
mov bx, STR_SPACE
call print_string
;show es - target
mov bx,es
mov al,bh
call print_hex_byte
mov al,bl
call print_hex_byte
mov bx, STR_SPACE
call print_string
;show next LBA numer
mov ax,[LBA]
mov al,ah
call print_hex_byte
mov ax,[LBA]
call print_hex_byte
mov bx, STR_SPACE
call print_string
popa
mov ax,[LBA]
;calculate chs
call lba_to_chs
;show chs sector/ head / cylinder
mov al,cl
call print_hex_byte
mov al,dh
call print_hex_byte
mov al,ch
call print_hex_byte
call print_nextline
skip_debug:
mov ax,[LBA]
;calculate chs
call lba_to_chs
; and now READ it!
mov al,1 ;number of sectors to read
mov dl,[BOOT_DRIVE]
mov ah,0x02 ;BIOS read sector func
int 0x13 ;bios interrupt
jc disk_read_error
mov bx,es
add bx,0x0020
cmp bx,0x9000
je disk_load_finish
mov es,bx
mov bx,0
mov ax,[LBA]
add ax,1
mov [LBA],ax
jmp next_sectors_chs
disk_read_error:
mov bx, STR_ERROR
call print_string
call print_nextline
jmp $
disk_load_finish:
mov bx, STR_PROGRESS
call print_string
; call print_nextline
popa
ret
;lba to chs translation:
; input : ax - lba
; output: cl - sector
; dh - head
; ch - cylinder / track
lba_to_chs:
xor dx, dx ; prepare dx:ax for operation
div WORD [bpbSectorsPerTrack] ; divide by sectors per track
inc dl ; add 1 (obsolute sector formula)
mov cl, dl
xor dx, dx ; prepare dx:ax for operation
div WORD [bpbHeadsPerCylinder] ; mod by number of heads (Absolue head formula)
mov dh,dl ; everything else was already done from the first formula
mov ch, al ; not much else to do :)
ret
;; here we hold the lba addr
lba_adr:
dw 0x10 ; size of packet ( 16 byte)
dw 64 ; number of sectors to read
; target is 0x10000
dw 0x0000 ; target addr. offset
lba_addr_sector:
dw 0x1800 ; target addr. sector
lba_first_sector:
dw 10 ; first sector to read
dw 0
dd 0
;
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