Use ATOMIC_BLOCK instead of cli() and sei() #40
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Use macros from util/atomic.h to prevent blocks of code from being
interrupted by interrupts.
`ATOMIC_BLOCK(ATOMIC_FORCEON) { /*...*/ }` is used in place of
`cli(); /*...*/ sei();` when global interrupts are already on, or when
global interrupts must be enabled afterwards anyway.
`ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { /*...*/ }` is used to save the
state of SREG (including the Global Interrupt Status flag) and restore
it afterwards.
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Thanks! I'll have to admit; I've never actually used atomic.h in any of my projects yet. I've done a little research, and as far as I've understood you use ATOMIC instead of cli/sei/SREG when dealing with variables that's shared between the main code and the ISR. So, I understand that this PR makes the code cleaner, but is it strictly necessary when allready using cli/sei/SREG? Seems like the official Arduino repo also saves SREG rather than using ATOMIC. I'm interested to know more about this atomic blocks and why a "dedicated library" is necessary to use 🙂 |
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Use macros from util/atomic.h to prevent blocks of code from being
interrupted by interrupts.
ATOMIC_BLOCK(ATOMIC_FORCEON) { /*...*/ }is used in place ofcli(); /*...*/ sei();when global interrupts are already on, or whenglobal interrupts must be enabled afterwards anyway.
ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { /*...*/ }is used to save thestate of SREG (including the Global Interrupt Status flag) and restore
it afterwards.