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{{DISPLAYTITLE:_LIMIT}} | {{DISPLAYTITLE:_LIMIT}} | ||
The [[_LIMIT]] statement sets the loop repeat rate of a program to so many per second, relinquishing spare CPU cycles to other applications. | The [[_LIMIT]] statement sets the loop repeat rate of a program to so many per second, relinquishing spare CPU cycles to other applications. | ||
{{PageSyntax}} | {{PageSyntax}} | ||
: [[_LIMIT]] {{Parameter|framesPerSecond!}} | : [[_LIMIT]] {{Parameter|framesPerSecond!}} | ||
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* _LIMIT measures its interval from the previous time that it was called and minor adjustments are automatically made to ensure that the number of times a loop is repeated is correct overall. | * _LIMIT measures its interval from the previous time that it was called and minor adjustments are automatically made to ensure that the number of times a loop is repeated is correct overall. | ||
* Loop cycle rates of 1000 or less can '''significantly reduce CPU usage''' in programs. | * Loop cycle rates of 1000 or less can '''significantly reduce CPU usage''' in programs. | ||
* Do not use it to limit a loop to '''less than once every 60 seconds'''(.0167) or an [[ERROR Codes|ILLEGAL FUNCTION CALL error]] will occur. | * Do not use it to limit a loop to '''run less than once every 60 seconds''' (i.e. _LIMIT .0167 or _LIMIT 1/60) or an [[ERROR Codes|ILLEGAL FUNCTION CALL error]] will occur. | ||
* Do not use _LIMIT as a timing delay outside of loops. Use [[_DELAY]] instead. | * Do not use _LIMIT as a timing delay outside of loops. Use [[_DELAY]] instead. | ||
* Use _LIMIT to slow down old QBasic program loops that run too fast and use too much CPU. | * Use _LIMIT to slow down old QBasic program loops that run too fast and use too much CPU. | ||
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''Example:'' Limits loop execution to 30 frames per second and limits the program's CPU usage. | ''Example:'' Limits loop execution to 30 frames per second and limits the program's CPU usage. | ||
{{CodeStart}} | {{CodeStart}} | ||
{{Cl|PRINT}} "To Quit press ESC key!" | {{Cl|PRINT}} {{Text|<nowiki>"To Quit press ESC key!"</nowiki>|#FFB100}} | ||
{{Cl|DO}} | {{Cl|DO}} | ||
{{Cl|_LIMIT}} {{Text|30|#F580B1}} | |||
{{Cl|PRINT}} {{Cl|CHR$}}({{Text|26|#F580B1}}); | |||
{{Cl|IF}} {{Cl|INKEY$}} = {{Cl|CHR$}}({{Text|27|#F580B1}}) {{Cl|THEN}} {{Cl|EXIT DO}} | |||
{{Cl|LOOP}} | {{Cl|LOOP}} | ||
{{CodeEnd}} | {{CodeEnd}} | ||
{{OutputStart}} | {{OutputStart}} | ||
| Line 40: | Line 40: | ||
{{PageNavigation}} | {{PageNavigation}} | ||
Latest revision as of 07:21, 13 April 2023
The _LIMIT statement sets the loop repeat rate of a program to so many per second, relinquishing spare CPU cycles to other applications.
Syntax
- _LIMIT framesPerSecond!
- The framesPerSecond! SINGLE parameter value adjusts the loops per second of a program loop. Do not use negative values.
- The loop code is executed before the loop is delayed. Loop cycles below once per second may delay program _EXITs.
- _LIMIT measures its interval from the previous time that it was called and minor adjustments are automatically made to ensure that the number of times a loop is repeated is correct overall.
- Loop cycle rates of 1000 or less can significantly reduce CPU usage in programs.
- Do not use it to limit a loop to run less than once every 60 seconds (i.e. _LIMIT .0167 or _LIMIT 1/60) or an ILLEGAL FUNCTION CALL error will occur.
- Do not use _LIMIT as a timing delay outside of loops. Use _DELAY instead.
- Use _LIMIT to slow down old QBasic program loops that run too fast and use too much CPU.
Examples
Example: Limits loop execution to 30 frames per second and limits the program's CPU usage.
PRINT "To Quit press ESC key!" DO _LIMIT 30 PRINT CHR$(26); IF INKEY$ = CHR$(27) THEN EXIT DO LOOP |
To Quit press ESC key! →→→→→→→→→→→→→→→→→→→→ |
- Note: In the above example, _LIMIT has to be within the loop.
See also