do - loop is thist a bug?

[elektriker]

symbol x = w5
pause 500

for x = 0 to 65438 step 777
     sertxd(#w5, cr, lf)
next x

sertxd("E N D", cr, lf)

This loop repeats 3 times !

 

[geoff07]

When I use the PE5 simulator it works as expected. Some more info regarding your test conditions would help.

 

[elektriker]

Hello geoff07.
I use Programming Editor Version 5.5.6 (Syntax DLL 262144).
MC is a Picaxe 08M2.

Danke

 

[hippy]

Seems to work as expected for me in PE5 (5.5.6) and PE6.

I do note your post is entitled "do - loop is this a bug?" yet there is no do-loop in the code.

 

[srnet]

This loop repeats 3 times !

Repeats 85 times here.

 

[Goeytex]

I get 85 times. (0 - 84) And there is no "do loop" in the code?

 

[elektriker]

hippy you are right, the title shot be "for-next is this a Bug?".

With Simulator PE 5.5.6 and PE6 it works right (0-84) ,
but when I prog. the Chip 08M2+ or 14M2 the Loop repeats 3 times * 84 (0-252) see the Txtfile.

Please have a look to the files and prog a real Chip.


Thanks
Werner

 

[hippy]

Thanks for clarifying.

It does seem there is a difference between how simulation and a real chip handles wrap-round overflow in a FOR-NEXT.

 

[srnet]

Is it the case that the simulator exits the for\next loop when the 'to' limit is exceeded, rather than overflowing and exiting when x actually does equal 65438 ?

 

[techElder]

For one thing, in case you are reading your output to make a determination of a problem, your code is printing out "#w5" instead of "x".

 

[oracacle]

x is w5, check the symbol at the top of the programme

 

[Technical]

for x = 0 to 65438 step 777

It is the chip that is correct:

 N=  81       62937
 N=  82       63714
 N=  83       64491
 N=  84       65268     <<<<<< 1      
 N=  85       509
 N=  86       1286

None of these numbers, due to the overflow, are bigger than 65438, hence another 'loop' starts.

The PE6 simulator issue is that it is allowing (65268 + 777) > 65438 to return true, thanks for letting us know, we will correct this bug in the next software update.
It should be using ( (65268 + 777) AND 65535) > 65438

 

[techElder]

I'm gonna have to stop drinking or programming ...

x is w5, check the symbol at the top of the programme

 

[grim_reaper]

I'm gonna have to stop drinking or programming ...

NONSENSE! Just ensure the order of processing is maintained... program, drink, sleep (loop!)