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cc65/libsrc/c128/cgetc.s
Oliver Schmidt 1d1ba3ed3b Adjusted constructors.
The constructors are _NOT_ allowed anymore to access the BSS. Rather they must use the DATA segment or the INIT segment. The latter isn't cleared at any point so the constructors may use it to expose values to the main program. However they must make sure to always write the values as they are not pre-initialized.
2016-03-16 16:28:32 +01:00

71 lines
1.7 KiB
ArmAsm

;
; Ullrich von Bassewitz, 06.08.1998
;
; char cgetc (void);
;
.export _cgetc
.constructor initcgetc
.destructor donecgetc
.import cursor
.include "c128.inc"
;--------------------------------------------------------------------------
_cgetc: lda KEY_COUNT ; Get number of characters
bne L2 ; Jump if there are already chars waiting
; Switch on the cursor if needed. We MUST always switch the cursor on,
; before switching it off, because switching it off will restore the
; character attribute remembered when it was switched on. So just switching
; it off will restore the wrong character attribute.
jsr CURS_SET ; Set cursor to current position
jsr CURS_ON
lda cursor
bne L1
lda #$01
jsr CURS_OFF
L1: lda KEY_COUNT ; Check characters again
beq L1
jsr CURS_OFF ; Switch cursor off, if characters available
L2: jsr KBDREAD ; Read char and return in A
ldx #0
rts
;--------------------------------------------------------------------------
; Module constructor/destructor
.segment "INIT"
keyvec: .res 2
.segment "ONCE"
initcgetc:
; Save the old vector
lda KeyStoreVec
ldx KeyStoreVec+1
sta keyvec
stx keyvec+1
; Set the new vector. I can only hope that this works for other C128
; versions...
lda #<$C6B7
ldx #>$C6B7
jmp SetVec
.code
donecgetc:
lda keyvec
ldx keyvec+1
SetVec: sei
sta KeyStoreVec
stx KeyStoreVec+1
cli
rts