N
Neo
Hi Folks,http://www.abarnett.demon.co.uk/tutorial.html#FASTFOR Page
states:for( i=0; i<10; i++){ ... }i loops through the values
0,1,2,3,4,5,6,7,8,9 If you don't care about the order of the loop counter,
you can do this instead: for( i=10; i--; ) { ... }Using this code, i loops
through the values 9,8,7,6,5,4,3,2,1,0, and the loop should be faster. This
works because it is quicker to process "i--" as the test condition, which
says "is i non-zero? If so, decrement it and continue.". For the original
code, the processor has to calculate "subtract i from 10. Is the result
non-zero? if so, increment i and continue.". In tight loops, this make a
considerable difference.
How far it holds true.. in the light of modern optimizing compilers? and
will it make a significant difference in case of embedded systems???
Thanks,
-Neo
"Do U really think, what U think real is really real?"
states:for( i=0; i<10; i++){ ... }i loops through the values
0,1,2,3,4,5,6,7,8,9 If you don't care about the order of the loop counter,
you can do this instead: for( i=10; i--; ) { ... }Using this code, i loops
through the values 9,8,7,6,5,4,3,2,1,0, and the loop should be faster. This
works because it is quicker to process "i--" as the test condition, which
says "is i non-zero? If so, decrement it and continue.". For the original
code, the processor has to calculate "subtract i from 10. Is the result
non-zero? if so, increment i and continue.". In tight loops, this make a
considerable difference.
How far it holds true.. in the light of modern optimizing compilers? and
will it make a significant difference in case of embedded systems???
Thanks,
-Neo
"Do U really think, what U think real is really real?"