empathicqubit/cc65
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Implemented a one-character buffer for kbhit() and cgetc().

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If kbhit() detects that a key is pressed, it fetches and
buffers the character. If cgetc() detects a buffered character,
this one is returned instead of fetching one with the PROM
routine.
This commit is contained in:
Stephan Mühlstrasser 2015-02-21 20:24:58 +01:00
parent b1969ac16a
commit 222668c016
5 changed files with 27 additions and 6 deletions
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2
cfg/osic1p.cfg
View file

@ -7,7 +7,7 @@ SYMBOLS {
}
MEMORY {
# for size of ZP see runtime/zeropage.s and c1p/extzp.s
ZP: file = "", define = yes, start = $0002, size = $001A + $0004;
ZP: file = "", define = yes, start = $0002, size = $001A + $0005;
RAM: file = %O, define = yes, start = %S, size = __HIMEM__ - __STACKSIZE__ - %S;
}
SEGMENTS {

19
libsrc/osic1p/cgetc.s
View file

@ -1,6 +1,8 @@
;
; char cgetc (void);
;
.constructor initcgetc
.export _cgetc
.import cursor
@ -8,8 +10,21 @@
.include "extzp.inc"
.include "zeropage.inc"
; Initialize one-character buffer that is filled by kbhit()
initcgetc:
lda #$00
sta CHARBUF ; No character in buffer initially
rts
; Input routine from 65V PROM MONITOR, show cursor if enabled
_cgetc:
lda CHARBUF ; character in buffer available?
beq nobuffer
tax ; save character in X
lda #$00
sta CHARBUF ; empty buffer
jmp restorex ; restore X and return
nobuffer:
lda cursor ; show cursor?
beq nocursor
ldy CURS_X
@ -25,7 +40,9 @@ nocursor:
lda tmp1 ; fetch saved character
ldy CURS_X
sta (SCREEN_PTR),y ; store at cursor position
restorex:
txa ; restore saved character from X
ldx #$00 ; high byte of int return value
done:
ldx #$00 ; high byte of int return value
rts

2
libsrc/osic1p/extzp.inc
View file

@ -4,4 +4,4 @@
; ------------------------------------------------------------------------
.globalzp CURS_X, CURS_Y, SCREEN_PTR
.globalzp CURS_X, CURS_Y, SCREEN_PTR, CHARBUF

5
libsrc/osic1p/extzp.s
View file

@ -14,6 +14,7 @@
CURS_X: .res 1
CURS_Y: .res 1
SCREEN_PTR: .res 2
CHARBUF: .res 1
; size 4
; Adjust size of this segment in osic1p.cfg if the size changes
; size 5
; Adjust size of the ZP segment in osic1p.cfg if the size changes

5
libsrc/osic1p/kbhit.s
View file

@ -19,10 +19,13 @@ scan:
rol a ; Rotate row select to next bit position
cmp #$FF ; Done?
bne scan ; If not, continue
ldx #$00 ; High byte of return is always zero
lda #$00 ; Return false
tax ; High byte of return is also zero
sta CHARBUF ; No character in buffer
rts
keypressed:
jsr INPUTC ; Get input character in A
sta CHARBUF ; Save in buffer
ldx #$00 ; High byte of return is always zero
lda #$01 ; Return true
rts