Fixed slowdown with repeated CDC bool operator test #3624
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Note that #3437 has a fix for the same issue. It works by saving the timestamp of a linestate change, which can prevent unneeded additional delays, but also needs 3 additional bytes of RAM. |
facchinm
added
the
USB: CDC serial
| result = true; | ||
| delay(10); | ||
| return result; | ||
| bool res = false; |
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I'd not rename it to res. Res sounds weird to me. Please keep result. The rest seems like a good idea to me.
facchinm
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to arduino/ArduinoCore-avr
that referenced
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Nov 13, 2017
Rebase and squash of arduino/Arduino#3624
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The
delay(10)in thebooloperator of the USB CDC/ACM Serial operator was being imposed on every single call to the operator when it is not needed. Instead thisdelay(10)should only be called when the line state transitions from ==0 to >0 (i.e., as the line enters the active state from the inactive state), otherwise repeated calls to (eg)if (Serial)cause the entire sketch to slow down to a crawl.By only imposing the delay when the line changes state it avoids that slowdown whilst at the same time giving the system a chance to complete the port opening operation before data is allowed to be sent.