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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;; Miguel's FoolOS Helper Functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[bits 16]
;global data
STR_HEX_OUT:
db "0x0000",0
;print_string routine ([bx])
;this routine will print a null terminated string at [bx] to the screen.
print_string:
pusha ;push all registers
mov ah,0x0e
print_string_loop:
;check if value at [bx] is "\0" (end of string)
mov cl,[bx]
cmp cl,0
je print_string_finish
;otherwise instruct BIOS to print the current char
mov al,cl
int 0x10
;proceed with next char
inc bx
jmp print_string_loop
print_string_finish:
popa ;pop all registers
ret ;return to caller
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;print_hex routine (dx)
;will print the value of the bx register as hex to the screen
print_hex:
pusha
;begin with last hex val (hex_out[5])
mov bx,STR_HEX_OUT+5
;lets loop throuth all 4 'digits'
print_hex_loop:
;get least significan hex digit to cx
mov cx,dx
and cx,0x000F
;check range (0-9 vs a-f)
cmp cx,10
jl print_hex_setnum
;set hex a-f
mov al,'A'-10
add al,cl
jmp print_hex_al
;set hex 0-9
print_hex_setnum:
mov al,'0'
add al,cl
; set hex_out[bx] to al
print_hex_al:
mov [bx],al
;proceed with the next significant hex 'digit'
dec bx
shr dx,4
;check if finished (otherwise loop)
cmp bx,STR_HEX_OUT+1
jne print_hex_loop
;output complete hex string and return to caller
mov bx,STR_HEX_OUT
call print_string
popa
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;disk_load routune (load dh sectors from drive dl to es:bx)
disk_load:
pusha
mov ah,0x02 ;BIOS read sector func
mov al,dh ;read dh sectors (amount)
mov ch,0x00 ;cyl 0
mov dh,0x00 ;head 0
mov cl,0x02 ;start at sector 2
int 0x13 ;bios interrupt
popa
ret
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