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cc65/libsrc/c64/readjoy.s

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;
; Ullrich von Bassewitz, 23.09.1998
;
; unsigned readjoy (unsigned char joy);
;
.export _readjoy
.include "c64.inc"
.proc _readjoy
tax ; Joystick number into X
bne joy2
; Read joystick 1
joy1: lda #$7F
sei
sta CIA1_PRA
lda CIA1_PRB
cli
and #$1F
eor #$1F
rts
; Read joystick 2
joy2: ldx #0
lda #$E0
ldy #$FF
sta CIA1_DDRA
lda CIA1_PRA
sty CIA1_DDRA
and #$1F
eor #$1F
rts
.endproc