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Hi,
I need to put a statement in a interrupt routine to shift a variable right one-bit. Like this:
dat >>=1;
It generated assembly code like this:
MOV A,dat CLR C RRC A MOV dat,A
What statement in C language sould be written to complete the shift operation but not effect the "C,carry" bit?
This is to save the "PUSH PSW", "POP PSW" instruction in my ISR. The inline assembly statement is not good to me, since I am not familar with it.
Thanks, John
High-level programming languages (eg, 'C') never, ever give you any guarantees about what specific machine instructions may or may not be generated by the compiler.
If this is of concern to you, then you must write your interrupt handler is assembler. (although, as Christoph Franck notes, the benefit is not major).