; vi:filetype=nasm ts=8 sts=8 sw=8:
%include "intr.inc"
%include "kbregs.inc"

	global kb_init
kb_init:
	set_irq_vector KB_IRQ, kbintr

	; enable keyboard interrupt
	mov eax, KB_CMD_GET_CMDBYTE
	call send_cmd
	call read_data
	or eax, KB_CCB_KB_INTREN	; set the INTREN flag
	push eax
	mov eax, KB_CMD_SET_CMDBYTE
	call send_cmd
	pop eax
	call send_data

	; flush the read buffer
	call wait_read
	jz .skipread
	call read_data
.skipread:

	unmask_irq KB_IRQ
	ret

	; keyboard interrupt handler
kbintr:
	pusha
	in al, KB_DATA_PORT
	cmp al, 0e0h
	jnz .noext
	mov byte [key_ext], 1
	jmp .eoi
.noext:
	; keystate[keycode] address in ebx
	xor ebx, ebx
	mov bl, al
	add ebx, keystate

	; determine if it's a press or release
	test al, 80h
	jz .press
	; key release
	mov byte [ebx], 0
	jmp .eoi
.press: ; key press
	mov byte [ebx], 1

.eoi:
	cli
	end_of_irq KB_IRQ

	popa
	iret

%macro iodelay 0
	xor al, al
	times 7 out 80h, al
%endmacro

wait_write:
	push eax
	push ecx
	mov ecx, 32768
.loop:	in al, KB_STATUS_PORT
	test al, KB_STAT_INBUF_FULL
	jz .break
	iodelay
	dec ecx
	jnz .loop
.break: pop ecx
	pop eax
	ret

wait_read:
	push eax
	push ecx
	mov ecx, 32768
.loop:	in al, KB_STATUS_PORT
	test al, KB_STAT_OUTBUF_FULL
	jnz .break
	iodelay
	dec ecx
	jnz .loop
.break: pop ecx
	pop eax
	ret

	; expects command in al
send_cmd:
	call wait_write
	out KB_CMD_PORT, al
	ret

read_data:
send_data:

	section .data
	align 4
key_ext: db 0

	global keystate
keystate: times 256 db 0