serial_bytes_available: don't double-count bytes on usb cdc#9400
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dhalbert merged 1 commit intoadafruit:mainfrom Jul 3, 2024
Merged
serial_bytes_available: don't double-count bytes on usb cdc#9400dhalbert merged 1 commit intoadafruit:mainfrom
dhalbert merged 1 commit intoadafruit:mainfrom
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In 9.0.x, serial_bytes_available returned a bool and tud_cdc_available was harmlessly checked twice for any characters. When the routine was changed to return an int, the double checking led to over-reporting the number of characters available. In code that would attempt to read this many bytes from sys.stdin, this made the read call block since only 1 byte was actually available. This behavior came up in the discussion of adafruit#9393. I don't mark this bug as closing that one, because that issue seems to be reporting multiple things that this change would not address, such as delays in `sys.stdout.write()` or problems seen while using webserial.
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In 9.0.x, serial_bytes_available returned a bool and tud_cdc_available was harmlessly checked twice for any characters.
When the routine was changed to return an int, the double checking led to over-reporting the number of characters available. In code that would attempt to read this many bytes from sys.stdin, this made the read call block since only 1 byte was actually available.
This behavior came up in the discussion of #9393. I don't mark this bug as closing that one, because that issue seems to be reporting multiple things that this change would not address, such as delays in
sys.stdout.write()or problems seen while using webserial.ping @gitcnd