2019-09-27 07:38:51 +00:00
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;
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2022-04-02 13:39:35 +00:00
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; 2021-04-01, Greg King
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2019-09-27 07:38:51 +00:00
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;
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; void waitvsync (void);
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2019-12-25 15:56:32 +00:00
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; /* Wait for the start of the next video field. */
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2019-09-27 07:38:51 +00:00
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;
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2019-12-25 15:56:32 +00:00
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; VERA's vertical sync causes IRQs which increment the jiffy timer.
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2022-08-05 22:44:18 +00:00
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;
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; Updated by ZeroByteOrg to use Kernal API RDTIM to retreive the TIMER variable
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2019-09-27 07:38:51 +00:00
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;
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.export _waitvsync
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2022-08-08 20:17:28 +00:00
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.importzp tmp1
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2019-09-27 07:38:51 +00:00
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2022-08-05 22:44:18 +00:00
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.proc _waitvsync: near
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RDTIM = $FFDE ; Kernal API for reading the jiffy timer
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jsr RDTIM
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2022-08-08 20:17:28 +00:00
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sta tmp1
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2022-08-05 22:44:18 +00:00
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keep_waiting:
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jsr RDTIM
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2022-08-08 20:17:28 +00:00
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cmp tmp1
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2022-08-05 22:44:18 +00:00
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beq keep_waiting
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rts
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.endproc
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