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.fopt compiler,"cc65 v 2.12.9"
.setcpu "6502"
.smart on
.autoimport on
.case on
.debuginfo off
.importzp sp, sreg, regsave, regbank, tmp1, ptr1, ptr2
.export _keybuf_init, _keybuf_poll_kbd, _keybuf_cgetc
NO_KEY = $FF
max_buf_len = 12 ; aka buffer size
BUFFER_BASE = $F0
keybuf_head = BUFFER_BASE
keybuf_tail = BUFFER_BASE+1
keybuf = BUFFER_BASE+2
keybuf_end = keybuf + max_buf_len
CH = $02FC
.segment "CODE"
; void __fastcall__ keybuf_init(void)
_keybuf_init:
lda #keybuf
sta keybuf_head
sta keybuf_tail
rts
; void __fastcall__ keybuf_poll_kbd(void)
_keybuf_poll_kbd:
lda CH
cmp #NO_KEY
beq kbpoll_done
; got a key, see if room in buffer
ldx keybuf_tail
cpx #keybuf_end+1
bcs kbpoll_done
; buffer not full, so store key in buffer
sta 0,x
inc keybuf_tail
; clear keyboard register
lda #NO_KEY
sta CH
kbpoll_done:
rts
; char __fastcall__ keybuf_is_empty(void)
_keybuf_is_empty:
ldx #0
sec
lda keybuf_tail
sbc keybuf_head
rts
; char __fastcall__ keybuf_cgetc(void)
; Note: 0 means "no key pressed", which means we
; can't return character code 0 (not a big deal).
; If this is a problem, we could change the return
; type to int, and return -1 instead.
_keybuf_cgetc:
ldx keybuf_head
cpx keybuf_tail
beq check_ch
; got a key, stuff it in CH
lda 0,x
sta CH
inc keybuf_head
call_cgetc:
; ...and return the ASCII code
jmp _fuji_cgetc
check_ch:
jsr _keybuf_init
ldx CH
cpx #NO_KEY
bne call_cgetc
inx ; was $FF, now 0
txa ; aka return(0)
rts
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