;
;disk_load_16
;

[bits 16]

STR_LBA:
    db "LBA Support Detected",0
    
STR_CHS:
    db "No CHS Support!)",0

STR_ERROR:
    db "Disk Read Error",0

STR_DONE:
    db "Stage 2 Loaded",0

disk_load_16:

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

disk_load_lba:

    mov bx, STR_LBA
    call print_string
    call print_nextline

    mov dl,[BOOT_DRIVE]
    xor ah,ah
    mov ah,0x42

    mov bx,0
    mov ds,bx
    lea si,[lba_adr]        

    int 0x13  
    jnc disk_load_finish
    jmp disk_load_error

disk_load_chs:

    mov bx, STR_CHS
    call print_string
    call print_nextline
    jmp $

    mov bx,0		;target es:bx
    mov es,bx
    mov bx,0x7e00

    mov al,50		;number of sectors to read
    mov ah,0x02		;BIOS read sector func

    mov cl,2 ; sector
    mov ch,0 ; cylinder

    mov dl,[BOOT_DRIVE]
    mov dh,0 ;head

    int 0x13		;bios interrupt

    jnc disk_load_finish  

disk_load_error:

    call print_nextline
    mov bx, STR_ERROR
    call print_string
    call print_nextline
    jmp $

disk_load_finish:

    call print_nextline
    mov bx, STR_DONE
    call print_string
    call print_nextline


    popa
    ret
  

;; here we hold the lba addr
lba_adr:

    dw 0x10	    ; size of packet ( 16 byte)
    dw 16	    ; number of sectors to read

    ; target is 0x7e00
    dw 0x7e00	    ; target addr. offset
    dw 0x0000	    ; target addr. sector

    dd 1	    ; first sector to read
    dd 0