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Arduino cheat sheet: Difference between revisions
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/* Now display the digits */
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==== Fast loops ====
[http://embeddedgurus.com/stack-overflow/2009/03/efficient-c-tips-7-fast-loops/ Efficient C Tips #7 – Fast loops « Stack Overflow]
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So how does this efficiency arise? Well in the count up case, the assembly language generated by the compiler typically looks something like this:
INC lpc ; Increment loop counter
SUB lpc, #10 ; Compare loop counter to 10
BNZ loop ; Branch if loop counter not equal to 10
By contrast, in the count down case the assembly language looks something like this
DEC lpc ; Decrement loop counter
BNZ loop ; Branch if non zero
Evidently, because of the ‘specialness’ of zero, more efficient code can be generated.
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