;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;; Miguel's FoolOS Helper Functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;disk_load_16
;

[bits 16]

DISK_LOAD:
    db "D",0
DISK_LOAD_ERROR
    db "E",0
Head:
    db 0
Track:
    db 0
Sector:
    db 1
LBA:
    dw 0 ;; starts at zero!
Sectors:
    dw 80
Heads:
    dw 2


;disk_load routune (load dh sectors from drive dl to es:bx)
;lba mode has 52 sectors hardcoded!
disk_load_16:

    pusha
    
;;;    ; check if LBA is supported
;;;    pusha
;;;    mov    ah,0x41
;;;    mov    bx,0x55aa
;;;    int    0x13                                                    
;;;    jnc disk_load_lba
;;;    popa

    disk_load_next:

    call ESBX

    ; load using CHS 
;;    mov al,80		;read dh sectors (amount)
;;    mov cx,[LBA]
;;    cmp cx,0
;;    jne disk_read_normal
;;    mov al,79		;read dh sectors (amount)
;;    disk_read_normal

    mov al,1

    mov cl,[Sector]	;sector
    mov ch,[Track]	;cyl

    mov dl,[BOOT_DRIVE]
    mov dh,[Head]	;head

    mov ah,0x02		;BIOS read sector func
    int 0x13		;bios interrupt

    jnc disk_read_ok  ;ready becaue of error :(

    mov bx, DISK_LOAD_ERROR
    call print_string

    jmp $

    disk_read_ok:

    mov ax,[LBA]

    cmp ax,880
    je disk_load_ready

    mov bx, DISK_LOAD
    call print_string

    add ax,1	;conver LBA to CHS
    mov [LBA],ax

    call LBACHS

    jmp disk_load_next

    disk_load_ready:

    jmp $

    popa
    ret
   
ESBX:

    xor dx,dx
    xor dx,dx
    mov ax,[LBA]
    mov bx,0x200
    mul bx
    mov bx,ax
    add dx,1
    shl dx,12
    mov es,dx

ret


    ; load using LBA

;;;disk_load_lba:
;;;
;;;    popa
;;;
;;;    xor ah,ah
;;;    mov ah,0x42
;;;    lea si,[lba_adr]        
;;;    int 0x13  
;;;    jc skip_print
;;;    mov bx, DISK_LOAD
;;;    call print_string
;;;    skip_print:
;;;
;;;    popa
;;;    ret
;;;
LBACHS:
          xor     dx, dx                              ; prepare dx:ax for operation
          div     WORD [Sectors]           ; divide by sectors per track
          inc     dl                                  ; add 1 (obsolute sector formula)
          mov     BYTE [Sector], dl
 
          xor     dx, dx                              ; prepare dx:ax for operation
          div     WORD [Heads]          ; mod by number of heads (Absolue head formula)
          mov     BYTE [Head], dl             ; everything else was already done from the first formula
 
          mov     BYTE [Track], al            ; not much else to do :)
          ret

lba_adr:

    dw 0x10	    ; size of packet ( 16 byte)

    dw 53	    ; number of sectors to read

    dw 0x0000	    ; target addr. offset
    dw 0x1000	    ; target addr. sector

    dd 1	    ; first sector to read
    dd 0	    ;