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cc65/libsrc/lynx/cgetc.s
cuz 14e40851e9 New kbhit and cgetc functions from Karri
git-svn-id: svn://svn.cc65.org/cc65/trunk@3295 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-11-13 10:34:06 +00:00

42 lines
958 B
ArmAsm

;
; Karri Kaksonen, 2004-11-01
;
; char cgetc (void);
;
.export _cgetc
.import _kbhit
.import KBBUF
; --------------------------------------------------------------------------
; The Atari Lynx has a very small keyboard - only 3 keys
; Opt1, Opt2 and Pause.
; But the designers have decided that pressing Pause and Opt1 at the
; same time means Restart and pressing Pause and Opt2 means Flip screen.
; For "easter egg" use I have also included all three keys pressed '?'
; and Opt1 + Opt2 pressed '3'.
; So the keyboard returns '1', '2', '3', 'P', 'R', 'F' or '?'.
_cgetc:
jsr _kbhit ; Check for char available
tax ; Test result
beq _cgetc
ldx #5 ; Wait for some time... 0.2 seconds or so.
@L1: ldy #255
@L2: lda #255
@L3: dec
bne @L3
dey
bne @L2
dex
bne @L1
jsr _kbhit ; Check for double pressed buttons
lda KBBUF
stz KBBUF
ldx #0
rts