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atrtimer.s: initialize the interrupt variables before enabling the interrupt

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This commit is contained in:
Christian Groessler 2017-09-25 17:06:43 +02:00
parent 24b663ef26
commit 969049face
1 changed files with 10 additions and 10 deletions
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20
drivers/atrtimer.s
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@ -27,19 +27,12 @@ vbichain: .word 0
.code
; reset timer to 0
; reset timer to 0 and install handler
; inputs: none
; outputs: none
timer_init:
lda vbichain+1
bne @handler_installed
ldax VVBLKI ; IMMEDIATE VERTICAL BLANK NMI VECTOR
stax vbichain ; save old immediate vector
ldy #<timer_vbl_handler
ldx #>timer_vbl_handler
lda #6 ; STAGE 1 VBI
jsr SETVBV ; vector to set VBLANK parameters
@handler_installed:
bne @done
lda PAL ; hardware register describing TV system of GTIA
and #$0e ; mask out irrelevant bits
bne @ntsc
@ -56,11 +49,18 @@ timer_init:
lda #17
sta timer_freq_reciproc
@system_set:
lda #0
lda #0 ; initialize time variables
sta current_time_value
sta current_time_value+1
sta current_seconds
sta current_jiffies
ldax VVBLKI ; IMMEDIATE VERTICAL BLANK NMI VECTOR
stax vbichain ; save old immediate vector
ldy #<timer_vbl_handler
ldx #>timer_vbl_handler
lda #6 ; STAGE 1 VBI
jsr SETVBV ; vector to set VBLANK parameters
@done:
rts
timer_exit: