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33 lines
965 B
Markdown
33 lines
965 B
Markdown
The WAIT statement waits until the value read from an I/O port has certain bits set.
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## Syntax
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> WAIT port%, andMask%[, xorMask%]
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## Description
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* The WAIT statement reads a value from port% using INP.
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* If xorMask% is specified, the value is XOR'd with xorMask%. It has the effect of "toggle these bits".
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* The value is then AND'd with andMask%. It has the effect of "check if these bits are set".
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* If the final value is non-zero, WAIT returns. Otherwise, another value is read from port% and checked again.
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* The WAIT statement returns immediately if port% is not supported.
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## Example(s)
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> Waiting for vertical retrace
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```vb
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' Either statement can be used to try to reduce screen flickering.
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' If both statements are used, try changing the order.
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WAIT &H3DA, 8 ' finishes whenever the screen isn't being written to
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WAIT &H3DA, 8, 8 ' finishes whenever the screen is being written to
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```
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## See Also
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* [INP](INP), [OUT](OUT)
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* [Scancodes](Scancodes)
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