.include "ps2_keyboard_text_handler.h65"
Export kb, init, char, keycode
Export kb, CHARS_NOMOD, CHARS_MODRALT, CHARS_MODSHIFT, CHARS_NUMLOCK_OFF, CHARS_NUMLOCK_ON
ExportZp kb, modifier

.zeropage
;; @ref kb::MOD "status of the modifier keys"
modifier:               .res 1
.bss
;; previous scancode is used to determine if a key was released (BREAK sent previously)
;; will be $ff if the previous scancode was K_BREAK
previous_scancode:      .res 1
;; 0 when no key or non-character key was pressed, otherwise character of the key (with modifiers applied)
char:                   .res 1
;; @ref kb::K "keycode" of the last key that was pressed or 0 if none was pressed
keycode:                .res 1

.code
;;********************************************************************************
;; @function Initialize the keyboard handler
;; @returns Z: Z = 1 => success, Z = 0 => failure
;; @details:
;;  Initializes the PS/2 keyboard driver and the handler.
;;  If any PS/2 command fails, init returns with Z = 0. The failed command (and parameter) can be loaded from `ps2kb::send_cmd` and `ps2kb::send_data`
;;  After init, the keyboard will be able to send scancodes.
;; @modifies A, X, Y
;;********************************************************************************
.proc init
    stz modifier
    stz char
    stz keycode
    stz previous_scancode

    jsr ps2kb::init

    ; init & reset
    ps2kb_CmdSelfTest
    ps2kb_WaitFinishCmd
    lda ps2kb::cmd_response+1
    cmp #$aa
    bne fail
    ; set set 3
    ps2kb_CmdSetScancodeSet 3
    ps2kb_WaitFinishCmd
    lda ps2kb::cmd_response+1
    cmp #ps2kb::ACK
    bne fail

    ; toggle-behaving keys
    ldx #kb::K::CAPSLOCK
    jsr set_make
    ldx #kb::K::NUMLOCK
    jsr set_make
    ldx #kb::K::SCROLLLOCK
    jsr set_make

    ; modifiers
    ldx #kb::K::LEFTSHIFT
    jsr set_make_release
    ldx #kb::K::RIGHTSHIFT
    jsr set_make_release
    ldx #kb::K::LEFTCTRL
    jsr set_make_release
    ldx #kb::K::RIGHTCTRL
    jsr set_make_release
    ldx #kb::K::LEFTALT
    jsr set_make_release
    ldx #kb::K::RIGHTALT
    jsr set_make_release
    ldx #kb::K::LEFTMETA
    jsr set_make_release
    ldx #kb::K::RIGHTMETA
    jsr set_make_release

    ps2kb_CmdEnable
    ps2kb_WaitFinishCmd
    lda ps2kb::cmd_response
    cmp #ps2kb::ACK
    bne fail

    StoreDByte process_scancode, ps2kb::scancode_handler
    jsr ps2kb::begin_receive
    lda #0  ; set Z = success
fail:
    rts

set_make:
    ; x must be set to scancode
    lda #$fd
    bra set
set_make_release:
    ; x must be set to scancode
    lda #$fc
set:
    ldy #0
    jsr ps2kb::send_command
    ps2kb_WaitFinishCmd
    lda ps2kb::cmd_response+1
    cmp #ps2kb::ACK
    bne fail
    rts
.endproc


;;********************************************************************************
;; @function Process a scancode
;; @details
;;  Update modifier bits if a mod key is pressed.
;;  If the key is not a mod key, the keycode is stored in @ref kb::keycode
;;  If the key is an ascii character, the corresponding ascii character is stored in @ref kb::char
;; @modifies A, X
;;********************************************************************************
.proc process_scancode
    ; check how this scancode needs to be interpreted
    ldx ps2kb::scancode
    bit previous_scancode
    jmi break_key       ; bit 7 set = BREAK

    cpx #$60  ; codes >= 60 in separate table to reduce memory consumption
    bcs x_ge_60
    bbs kb::MOD::SHIFT, modifier, modshift         ; if shift active
    bbs kb::MOD::RALT, modifier, modralt           ; if ralt active

; load from the correct table, if 0 => non-char, if 1 => non-char but mod, else char
nomod:
    lda CHARS_NOMOD,x 
    bra check_char
modralt:
    lda CHARS_MODRALT,x 
    bra check_char
modshift:
    lda CHARS_MODSHIFT,x 
check_char:
    beq not_mod     ; 0 => not mod and not char
    cmp #1          ; 1 => mod
    beq is_mod
@char:              ; store char
    sta char
not_mod:            ; store keycode if not mod
    stx keycode
_rts:
    rts

x_ge_60:         ; x >= $60
    cpx #$90  ; only BREAK is higher than 8F, (also code table only has 8F bytes)
    bcs check_release
    ; CHARS_NUMLOCK_OFF - CHARS_NOMOD = 60 -> no need to subtract $60 first
    ; CHARS_NUMLOCK_ON - CHARS_MODSHIFT = 60 -> no need to subtract $60 first
    bbs kb::MOD::NUMLOCK, modifier, modshift     ; if numlock active
    lda CHARS_NOMOD,x   
    bra check_char
check_release:  ; x >= $90
    cpx #kb::K_BREAK
    bne _rts
    lda #$ff
    sta previous_scancode
    rts

is_mod:
    ; check which mod
    cpx #kb::K::LEFTSHIFT
    beq set_shift
    cpx #kb::K::RIGHTSHIFT
    beq set_shift
    cpx #kb::K::RIGHTALT
    beq set_rightalt
    cpx #kb::K::LEFTALT
    beq set_leftalt
    cpx #kb::K::RIGHTMETA
    beq set_meta
    cpx #kb::K::LEFTMETA
    beq set_meta
    cpx #kb::K::RIGHTCTRL
    beq set_ctrl
    cpx #kb::K::LEFTCTRL
    beq set_ctrl
    cpx #kb::K::CAPSLOCK
    beq toggle_capslock
    cpx #kb::K::NUMLOCK
    beq toggle_numlock
    cpx #kb::K::SCROLLLOCK
    beq toggle_scrolllock

    ; a real keycode and not a released keycode, twobyte or release scancode

set_ctrl:
    smb kb::MOD::CTRL, modifier
    rts
set_meta:
    smb kb::MOD::META, modifier
    rts
set_leftalt:
    smb kb::MOD::LALT, modifier
    rts
set_rightalt:
    smb kb::MOD::RALT, modifier 
    rts
set_shift:                                              ; process shift
    bbs kb::MOD::CAPSLOCK, modifier, @unset_shift   ; CAPSLOCK unset shift when capslock is on
@set_shift:
    smb kb::MOD::SHIFT, modifier  
    rts
@unset_shift:
    rmb kb::MOD::SHIFT, modifier  
    rts

toggle_numlock:               ; toggle numlock
    lda modifier
    eor #kb::MOD::NUMLOCK   
    sta modifier
    bra update_leds
toggle_scrolllock:             ; toggle numlock
    lda modifier
    eor #kb::MOD::SCROLLLOCK
    sta modifier
    bra update_leds
toggle_capslock:              ; toggle capslock & shift
    lda modifier
    eor #(kb::MOD::CAPSLOCK | kb::MOD::SHIFT)
    sta modifier
    ; fallthrough
load_update_leds:
    lda modifier
update_leds:
    and #%00000111  ; only bottom 3 bits allowed - otherwise command fails
    tax
    ps2kb_CmdSetLeds
    rts
.endproc

;;********************************************************************************
;; @details
;;  Unset modifier bits if a mod key is released.
;; @param X: The scancode
;; @modifies: 
;;********************************************************************************
.proc break_key
    ; rmb kb::PREVIOUS::BREAK, kb::previous_scancode 
    stz previous_scancode

    ; check mod keys
    cpx #kb::K::LEFTSHIFT
    beq unset_shift
    cpx #kb::K::RIGHTSHIFT
    beq unset_shift
    cpx #kb::K::RIGHTALT
    beq unset_rightalt
    cpx #kb::K::LEFTALT
    beq unset_leftalt
    cpx #kb::K::RIGHTMETA
    beq unset_meta
    cpx #kb::K::LEFTMETA
    beq unset_meta
    cpx #kb::K::RIGHTCTRL
    beq unset_ctrl
    cpx #kb::K::LEFTCTRL
    rts
unset_shift:                                        ; process shift
    bbs kb::MOD::CAPSLOCK, modifier, @set_shift     ; set shift when capslock is on
    rmb kb::MOD::SHIFT, modifier                    ; unset if capslock is off
    rts
@set_shift:
    smb kb::MOD::SHIFT, modifier
    rts
unset_ctrl:
    rmb kb::MOD::CTRL, modifier
    rts
unset_meta:
    rmb kb::MOD::META, modifier
    rts
unset_leftalt:
    rmb kb::MOD::LALT, modifier
    rts
unset_rightalt:
    rmb kb::MOD::RALT, modifier 
    rts
.endproc

.rodata
.align 256
CHARS_NOMOD:
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00^\x00"
	.byte "\x00\x01\x01<\x01q1\x00\x00\x01ysaw2\x00"
	.byte "\x00cxde43\x00\x00 vftr5\x00"
	.byte "\x00nbhgz6\x00\x00\x01mju78\x00"
	.byte "\x00,kio09\x00\x00.-l\xEFp\xE2\x00"
	.byte "\x00\x00\xE1#\xF5`\x00\x00\x01\x01\x00\x00\x00\x00\x00\x01"
;; numlock range characters where numlock is off
CHARS_NUMLOCK_OFF:
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
	.byte "\x00\x00\x00\x00\x00\x00\x01/\x00\x00\x00\x00+\x00*\x00"
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00-\x00"
CHARS_MODSHIFT:
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xDF\x00"
	.byte "\x00\x01\x01>\x01Q!\x00\x00\x01YSAW\"\x00"
	.byte "\x00CXDE$\xED\x00\x00 VFTR%\x00"
	.byte "\x00NBHGZ&\x00\x00\x01MJU/(\x00"
	.byte "\x00;KIO=)\x00\x00:_L\xEFP\xE2\x00"
	.byte "\x00\x00\xE1'\xF5`\x00\x00\x01\x01\x00\x00\x00\x00\x00\x01"
CHARS_NUMLOCK_ON:
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x001\x0047\x00\x00\x00"
	.byte "0.2568\x01\x00\x00\x003\x00\x009\x00\x00"
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00"
CHARS_MODRALT:
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\x00"
	.byte "\x00\x01\x01|\x01\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00"
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00{[\x00"
	.byte "\x00\x00\x00\x00\x00}]\x00\x00\xA5\xB0\x00\x00\x00\x00\x00"
	.byte "\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x01"