Keyboard.asm

; =========================================================
; Module: Keyboard
; =========================================================
; Description:
;     Routines for handling an AT or PS/2 keyboard.
; Functions:
;     Initialise: Detect, reset, initialise the mouse.
;     Update:     Read the status of the mouse and update
;                 variables.
; Variables:
;     Position:   Position of the mouse and scrollwheel.
;     Status:     Status of the buttons and mouse mode.
; =========================================================

.module Keyboard
; ---------------------------------------------------------
; GetScancode -> Retrieve a scancode from the keyboard.
; ---------------------------------------------------------
; Inputs:   None.
; Outputs:  z on success, nz on failure.
;           a    = scancode
;           c    = reset for press, set for release.
;           s    = set for extended key.
; Destroys: af, bc, de, hl
; ---------------------------------------------------------

GetScancode:
	ld l,64
	call AT.GetByte
	ret nz
	cp $E1
	jr z,GetPauseScancode
	cp $E0
	jr nz,+
	ld l,128|64
	call AT.GetByte
	ret nz
+:	cp $F0
	jr nz,+
	inc l
	call AT.GetByte
	ret nz
+:	ld h,a
	push hl
	pop af
	ret

GetPauseScancode:
	ld b,7
-:	push bc
	call AT.GetByte
	pop bc
	ret nz
	djnz -
	ld hl,64+$E1*256
	push hl
	pop af
	ret

LayoutFileDescription = allocVar(2)

LayoutFile = allocVar(0)
LayoutFile.StandardTableSize = allocVar(2)    ; Number of standard scancodes.
LayoutFile.ExtendedTableSize = allocVar(2)    ; Number of extended scancodes.
LayoutFile.ModifiersLookup = allocVar(2)      ; Address of modifier lookup list.
LayoutFile.ModifiersJumpTable = allocVar(2)   ; Address of modifier jump table.
LayoutFile.StandardTableAddress = allocVar(2) ; Address of standard scancode table.
LayoutFile.ExtendedTableAddress = allocVar(2) ; Address of extended scancode table.
LayoutFile.KeyOffsetTable = allocVar(2)       ; Address of key jump table.
LayoutFile.KeyDataTable = allocVar(2)         ; Address of key data table.
LayoutFile.KeyTypeTable = allocVar(2)         ; Address of the key type table.
LayoutFile.Size = allocVar(0) - LayoutFile

Status = allocVar(1)
LedState = allocVar(1)

OriginalScancode = allocVar(2)


; ---------------------------------------------------------
; LoadManualLayout -> Loads a keyboard layout definition.
; ---------------------------------------------------------
; Inputs:   hl = address of layout definition data.
; Destroys: af, bc, de, hl, ix
; ---------------------------------------------------------

LoadManualLayout:
	ld (OriginalScancode),hl ; Temp
	ld de,LayoutFile
	ld bc,LayoutFile.Size
	ldir
	ld (LayoutFileDescription),hl
	
	ld ix,LayoutFile + 4
	
	ld b,(LayoutFile.Size / 2) - 2
-:	ld e,(ix+0) \ ld d,(ix+1)
	ld hl,(OriginalScancode)
	add hl,de
	ld (ix+0),l \ ld (ix+1),h
	inc ix \ inc ix
	djnz -

	xor a
	ld (Status),a
	ld (LedState),a
	ret
	
; ---------------------------------------------------------
; ConvertScancode -> Convert a scancode to a key code.
; ---------------------------------------------------------
; Inputs:   a    = scancode.
;           c    = reset for press, set for release.
;           s    = set for extended key.
; Outputs:  z on matched key.
;           a    = key code.
;           c    = reset for press, set for release.
;           s    = set for non-printable key.
; Destroys: af, bc, de, hl
; ---------------------------------------------------------

ConvertScancode:
	push af
	pop hl
	ld (OriginalScancode),hl	
	ld hl,(LayoutFile.StandardTableAddress)
	ld d,h \ ld e,l
	ld bc,(LayoutFile.StandardTableSize)
	jp p,+
	ld hl,(LayoutFile.ExtendedTableAddress)
	ld bc,(LayoutFile.ExtendedTableSize)
+	
	push bc
	cpir
	pop bc
	ret nz
+	
	push hl
	push hl
	ld hl,(LayoutFile.StandardTableSize)
	ld b,h \ ld c,l
	ld hl,(LayoutFile.ExtendedTableSize)
	add hl,bc
	ld b,h \ ld c,l
	pop hl
	scf
	sbc hl,bc
	ld a,(hl)
	pop hl
	push af
	
	scf
	sbc hl,de
	add hl,hl
	ld de,(LayoutFile.KeyOffsetTable)
	add hl,de
	ld e,(hl) \ inc hl
	ld a,(hl)
	push af
	and ~%11000000
	ld d,a
	add hl,de
	; hl->key info block.

	pop af
	bit 7,a
	jr z,IsNotModifier
	bit 6,a
	jr z,NotToggle
	
	; This is a toggling modifier, e.g. Caps Lock.
	ld a,(OriginalScancode)
	bit 0,a
	jr z,TogglePushed
	
ToggleReleased:
	inc hl
	ld a,(hl)
	cpl
	rlca \ rlca \ rlca \ rlca
	ld e,a
	ld a,(LedState)
	and e
	ld (LedState),a
	jr IsNotModifier

TogglePushed
	inc hl
	ld a,(hl)
	rlca \ rlca \ rlca \ rlca
	ld e,a
	ld a,(LedState)
	ld d,a
	and e
	jr nz,IsNotModifier
	ld a,d
	or e
	ld (LedState),a
	dec hl
	
	ld a,(Status)
	xor (hl)
	ld (Status),a
	inc hl
	ld a,(LedState)
	xor (hl)
	ld (LedState),a
	
	ld a,$ED
	call AT.SendSafeByte
	ld a,(LedState)
	and %111
	call AT.SendSafeByte
	
	inc hl
	jr IsNotModifier
	
NotToggle
	ld a,(OriginalScancode)	
	bit 0,a
	jr nz,StatusOff
	ld a,(Status)
	or (hl)
	jr +
StatusOff
	ld a,(Status)
	ld b,a
	ld a,(hl)
	cpl
	and b
+:	ld (Status),a
	inc hl

IsNotModifier
	ld a,(Status)
	and (hl)
	jr z,NoStatusModifiers
	
	; Now we need to work out the index:
	
	ld b,(hl)
	push hl

	push af
	ld a,b

	ld bc,0
	ld hl,(LayoutFile.ModifiersLookup)
	ld d,h \ ld e,l
	cpir
	dec hl
	or a
	sbc hl,de
	add hl,hl
	ld de,(LayoutFile.ModifiersJumpTable)
	add hl,de
	
	ld e,(hl)
	inc hl
	ld d,(hl)
	add hl,de

	ld d,h \ ld e,l
	
	pop af
	cpir
	or a
	sbc hl,de
	ld d,h \ ld e,l
	dec de		
	pop hl
	add hl,de
	
NoStatusModifiers:
	inc hl
	ld a,(hl)
	cp $FF
	jr z,ExitNoKey

	ld d,a
	
	ld bc,(LayoutFile.KeyDataTable)
	or a
	sbc hl,bc	
	ld a,l
	and 7
	inc a
	ld e,a
	
	srl h \ rr l
	srl h \ rr l
	srl h \ rr l
	
	ld bc,(LayoutFile.KeyTypeTable)
	add hl,bc
	ld a,(hl)
	ld b,e
-:	sla a
	djnz -
	
	; Carry = non-printable key.

	ld a,(OriginalScanCode)
	
	res 7,a ; S
	jr nc,+
	set 7,a
+:
	
	set 6,a ; Z
	ld e,a
	push de
	pop af
	pop de
	ret

ExitNoKey:
	xor a
	dec a
	pop de
	ret

; ---------------------------------------------------------
; GetKey -> Retrieves a key from the keyboard.
; ---------------------------------------------------------
; Inputs:   None
; Outputs:  z on valid key input.
;           a    = key code.
;           c    = reset for press, set for release.
;           s    = set for non-printable key.
; Destroys: af
; ---------------------------------------------------------
	
GetKey:
	push hl
	push bc
	call GetScancode
	jr nz,+
	call ConvertScancode
+:	pop bc
	pop hl
	ret

; .........................................................
; Equates for the non-printable key codes
; .........................................................
.module KeyCode
    F1           = $00
    F2           = $01
    F3           = $02
    F4           = $03
    F5           = $04
    F6           = $05
    F7           = $06
    F8           = $07
    F9           = $08
    F10          = $09
    F11          = $0A
    F12          = $0B
    
    Up           = $0C
    Down         = $0D
    Left         = $0E
    Right        = $0F
    
    PageUp       = $10
    PageDown     = $11
    
    Insert       = $12
    
    PrintScreen  = $13
    
    Home         = $14
    End          = $15
    
    CtrlLeft     = $16
    CtrlRight    = $17
    
    Alt          = $18
    AltGr        = $19
    
    ShiftLeft    = $1A
    ShiftRight   = $1B
    
    WindowsLeft  = $1C
    WindowsRight = $1D
    
    CapsLock     = $1E
    NumLock      = $1F
    ScrollLock   = $20
    
    Application  = $21
    
    Power        = $22
    Sleep        = $23
    Wake         = $24
    
    Escape       = $25
    Pause        = $26
.endmodule

.endmodule