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Merge pull request #1821 from ZeroByteOrg/x16_waitvsync

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CX16 waitvsync uses Kernal API to retreive jiffies
This commit is contained in:
Bob Andrews
2022-08-09 19:02:15 +02:00
committed by GitHub
parent e30e233064 582e43931d
commit bdcc5ba549
1 changed files with 13 additions and 10 deletions
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23
libsrc/cx16/waitvsync.s
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@@ -5,17 +5,20 @@
; /* Wait for the start of the next video field. */ ; /* Wait for the start of the next video field. */
; ;
; VERA's vertical sync causes IRQs which increment the jiffy timer. ; VERA's vertical sync causes IRQs which increment the jiffy timer.
;
; Updated by ZeroByteOrg to use Kernal API RDTIM to retreive the TIMER variable
; ;
.export _waitvsync .export _waitvsync
.importzp tmp1
.import RDTIM
.include "cx16.inc" .proc _waitvsync: near
jsr RDTIM
_waitvsync: sta tmp1
ldx RAM_BANK ; (TIMER is in RAM bank 0) keep_waiting:
stz RAM_BANK jsr RDTIM
lda TIMER + 2 cmp tmp1
: cmp TIMER + 2 beq keep_waiting
beq :- ; Wait for next jiffy rts
stx RAM_BANK .endproc
rts