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git-svn-id: svn://svn.cc65.org/cc65/trunk@1384 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz 2002-08-09 05:07:06 +00:00
parent 12154bdaa7
commit 94ea416652
1 changed files with 12 additions and 13 deletions
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25
libsrc/vic20/readjoy.s
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@ -16,26 +16,25 @@
.proc _readjoy
lda #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
ldx #$7F ; mask for VIA2 JOYBIT: sw3
lda #$7F ; mask for VIA2 JOYBIT: sw3
ldx #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
sei ; necessary?
ldy VIA1_DDRA ; remember the state of DDRA
sta VIA1_DDRA ; set JOYBITS on this VIA for input
lda VIA1_JOY ; read JOYBITS: sw0,sw1,sw2,sw4
sty VIA1_DDRA ; restore the state of DDRA
and #$3C ; Mask relevant bits...
sta tmp1 ; ...and save for later
ldy VIA2_DDRB ; remember the date of DDRB
stx VIA2_DDRB ; set JOYBITS on this VIA for input
sta VIA2_DDRB ; set JOYBITS on this VIA for input
lda VIA2_JOY ; read JOYBIT: sw3
sty VIA2_DDRB ; restore the state of DDRB
asl ; Shift sw3 into carry
ldy VIA1_DDRA ; remember the state of DDRA
stx VIA1_DDRA ; set JOYBITS on this VIA for input
lda VIA1_JOY ; read JOYBITS: sw0,sw1,sw2,sw4
sty VIA1_DDRA ; restore the state of DDRA
cli ; necessary?
and #$80 ; Mask sw3
ora tmp1 ; Get sw0, sw1, sw2, sw4
eor #$BC ; Active states are inverted
ror ; Shift sw3 into bit 7
and #$9E ; Mask relevant bits
eor #$9E ; Active states are inverted
rts