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section .text
align 4
global kmain
global interrupt_handler
extern idt_init
extern pio_read
extern pio_write
interrupt_handler:
mov ebx, [esp + 34]
shr ebx, 16
cmp ebx, 0x21
je .int21
jmp .end
.int21:
cmp ah, 0x1
je .int21.kprint
jmp .end
.int21.kprint:
;sub esp, 4
;mov [esp - 4], bx
;shr bx, 8
;push word bx
;mov bx, [esp - 4]
;and bx, 0xff
;push bx
;call screen_gotoxy
;add esp, 8
push edx
call kprint
add esp, 4
.end:
ret
cursor_move:
push ebp
mov ebp, esp
sub ebp, 4
call screen_getxy
mov [ebp - 4], eax
push 0x3D4
push 14
call pio_write
mov ebx, [ebp + 4]
shr ebx, 8
push 0x3D5
push word [ebx]
call pio_write
push 0x3D4
push 15
call pio_write
mov ebx, [ebp + 4]
push 0x3D5
push word [ebx]
call pio_write
add ebp, 4
leave
ret
screen_fill:
; = purpose
; Fills the screen with a character and color
;
; = stack arguments (order of use)
; push ' ' ; character
; push 0x07 ; color attribute
push ebp
mov ebp, esp
xor eax, eax ; clear eax
mov eax, [ebp + 8] ; get character
shl eax, 8 ; shift character into MSB
or eax, [ebp + 12] ; set color attribute
mov ecx, CONSOLE_SIZE ; use entire screen
mov edi, screen_buffer ; destination = screen_buffer
cld ; will increment esi and edi
rep stosw ; char+color -> screen_buffer
mov esp, ebp
pop ebp
ret
screen_refresh:
push ebp
mov ebp, esp
pusha
mov ecx, CONSOLE_SIZE ; use entire screen
mov esi, screen_buffer ; source = screen_buffer
mov edi, VIDEO_RAM ; destination = video RAM
cld ; will increment esi and edi
rep movsw ; char+color -> screen_buffer
popa
mov esp, ebp
pop ebp
ret
screen_gotoxy:
push ebp
mov ebp, esp
pusha
; y * width + x
mov ebx, CONSOLE_W * 2
mov eax, [ebp + 12]
mul ebx
add eax, [ebp + 8]
mov [screen_pos], eax
popa
leave
ret
screen_getxy:
push ebp
mov ebp, esp
mov eax, [screen_pos]
leave
ret
screen_updatexy:
push ebp
mov ebp, esp
add word [screen_pos], 2
cmp word [screen_pos], CONSOLE_SIZE
call screen_scroll_up
leave
ret
screen_scroll_up:
push ebp
mov ebp, esp
nop
leave
ret
screen_scroll_down:
push ebp
mov ebp, esp
nop
leave
ret
kprint:
; = purpose
; Writes a buffer to the screen
;
; = globals
; kprint_delay: if != 0; echo slowly
;
; = stack arguments (order of use)
; push buffer
push ebp
mov ebp, esp
xor ebx, ebx
xor esi, esi
xor edi, edi
mov esi, [ebp + 8] ; source buffer
mov edi, screen_buffer ; output to screen buffer
mov ebx, [screen_pos] ; get current screen position
add edi, ebx ; move to current screen position
mov ecx, 0xff ; delay counter
.write:
cmp byte [kprint_delay], 0 ; determine if we want a delay
je .nodelay ; if kprint_nodelay == 0:
; nodelay()
; else:
; delay()
.delay:
dec ecx ; while ecx != 0: ecx--
call screen_refresh
jne .delay
.nodelay:
mov ebx, [esi] ; get value from source buffer
mov [edi], bl ; write value to screen buffer
inc esi ; next char in source buffer
add edi, 2 ; skip over screen attribute byte
call screen_updatexy ; update screen_pos
cmp bl, 0 ; if ch != 0: write
jne .write
call screen_refresh ; dump screen buffer to video ram
leave
ret
kputc:
push ebp
mov ebp, esp
mov esi, [screen_pos]
mov edi, screen_buffer
add edi, esi
mov [edi], dl
call screen_updatexy
call screen_refresh
leave
ret
kprintnl:
push ebp
mov ebp, esp
nop
leave
ret
kmain:
push ebp
mov ebp, esp
mov byte [screen_pos], 2 ; Initialize screen position
;call cursor_move
call idt_init
; Fill screen with
push ' ' ; spaces &&
push 0x07 ; white forground on blue background
call screen_fill ; fill the screen buffer
call screen_refresh ; dump screen buffer to video ram
;push 12
;push 30
;call screen_gotoxy
;mov byte [kprint_delay], 1 ; tell kprint to delay writes
push message ; push message address as argument
call kprint ; print message
call kprintnl
mov dl, 'A'
call kputc
mov word [VIDEO_RAM + CONSOLE_SIZE - 6], \
0x4F << 8 | 'I' ; END OF MAIN MARKER
;mov ah, 1
;mov bh, 2
;mov bl, 2
;mov edx, message2
;int 21h ; here goes nothing
mov word [VIDEO_RAM + CONSOLE_SIZE - 6], \
0x2F << 8 | 'I' ; END OF MAIN MARKER
mov word [VIDEO_RAM + CONSOLE_SIZE - 4], \
0x2F << 8 | 'K' ; END OF MAIN MARKER
mov esp, ebp
pop ebp
ret
section .data
%include 'constants.asm'
message: db 'Kernel programming is fun!', 0
message2: db 'This is a test.', 0
section .bss
kprint_delay: resb 1
screen_pos: resd 1
screen_buffer: resb CONSOLE_SIZE
screen_buffer_end:
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