Limit of 8 nested blocks exceeded?
turbosupra
Posts: 1,088
I'm sure there is a more efficient way (and far better way) to code this, but I'm not Hano (I'm very new to this) and so I'm wondering what the purpose of this 8 nested blocks limit is for?
Here is my loop, thoughts?
Here is my loop, thoughts?
repeat
repeat
Debug.Str(string(" Waiting to enter repeat loop",13))
firstloopcnt := cnt
if ina[noparse][[/noparse]PulseInputPin] == 1
timeoffirstpulse := cnt '(cnt/1000) ' 90
Debug.Str(string("1st if PulseInputPin == 1 true",13))
Debug.Str(string("timeoffirstpulse := cnt value is:"))
Debug.Dec(||timeoffirstpulse)
Debug.Tx(13)
Debug.Tx(13)
'Debug.Str(string("About to hit the 40 million hz waitcnt in 1st loop",13))
'waitcnt(ClkFreq/2 + cnt)
secondloopcnt := cnt
lowhigh1_detected := true
if ina[noparse][[/noparse]PulseInputPin] == 0 AND lowhigh1_detected == true
highlow1_detected := true
Debug.Str(string("lowhigh1_detected and highlow1_detected, entering 2nd loop",13))
repeat
if ina[noparse][[/noparse]PulseInputPin] == 1 AND highlow1_detected == true
timeofsecondpulse := cnt '(cnt/1000) ' 90
Debug.Str(string("2nd if PulseInputPin == 1 true",13))
Debug.Str(string("timeofsecondpulse := cnt value is:"))
Debug.Dec(||timeofsecondpulse)
Debug.Tx(13)
Debug.Tx(13)
'Debug.Str(string("About to hit the 40 million hz waitcnt in 2nd loop",13))
'waitcnt(ClkFreq/2 + cnt)
thirdloopcnt := cnt
lowhigh2_detected := true
if ina[noparse][[/noparse]PulseInputPin] == 0 AND lowhigh2_detected == true
highlow2_detected := true
Debug.Str(string("highlow2_detected, entering 3nd loop",13))
repeat
if ina[noparse][[/noparse]PulseInputPin] == 1 AND highlow2_detected == true
timeoffirstpulse := cnt '(cnt/1000) ' 90
Debug.Str(string("3rd if PulseInputPin == 1 true",13))
Debug.Str(string("timeofsecondpulse := cnt value is:"))
Debug.Dec(||timeofsecondpulse)
Debug.Tx(13)
Debug.Tx(13)
'Debug.Str(string("About to hit the 40 million hz waitcnt in 3rd loop",13))
'waitcnt(ClkFreq/2 + cnt)
Debug.Str(string("Outputting to pin",13))
outa[noparse][[/noparse]OutPutPin] := 1
WaitCnt((ClkFreq / 1000 * fullsec_wait) * 2 + cnt) ' leave output pin set to high for a full second
Debug.Str(string("Done outputting to pin",13))
outa[noparse][[/noparse]OutPutPin] := 0
quit
elseif thirdloopcnt =< (- 120_000_000 + cnt)
Debug.Str(string("3rd loop timeout, quitting",13))
'waitcnt(ClkFreq/2 + cnt)
quit
elseif secondloopcnt =< (- 120_000_000 + cnt)
lowhigh2_detected := false
Debug.Str(string("2nd loop timeout, quitting",13))
'waitcnt(ClkFreq/2 + cnt)
quit
elseif firstloopcnt =< (- 120_000_000 + cnt)
lowhigh1_detected := false
Debug.Str(string("1st loop timeout, quitting",13))
'waitcnt(ClkFreq/2 + cnt)
next ' **wanted to change this to quit**
Comments
The limit on nesting has to do with some table inside the compiler that was arbitrarily limited to 8 entries when the compiler was designed. For REPEATs and IFs, there has to be some information kept around so internal labels and other related stuff can be kept around while the code is being generated.
It's usually clearer programming to keep nesting to 3 or 4 levels and moving deeper stuff into subroutines. The additional call overhead is pretty low at that point.
I think your code example answers that question nicely. As you see after a few levels of indentation it becomes very hard to tell what the hell is going on in the code.
Some would say the language, Spin in the case, should not impose arbitrary limits on such things.
I'm happy enough with a depth of 8 especially as Spin has no braces or block end markers it soon
becomes hard to see the form of the code.
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For me, the past is not over yet.
The opening example has indentation all over the place making it hard to see the original intent (not indent).
Perhaps that's how it was written, perhaps it got mangled as it is made it way to this web page. Impossible to tell.
Still let's not have yet another "white space block delimiter or not" debate.
As you say the issue here is the same regardless.
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For me, the past is not over yet.
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Propeller Pages: Propeller JVM
If so, is there any issue with the variables inside of the Main method being read by the Sigout method? I assume there is not because they are not defined as local, but I wanted to make sure
repeat repeat Debug.Str(string(" Waiting to enter repeat loop",13)) firstloopcnt := cnt if ina[noparse][[/noparse]PulseInputPin] == 1 timeoffirstpulse := cnt '(cnt/1000) ' 90 Debug.Str(string("1st if PulseInputPin == 1 true",13)) Debug.Str(string("timeoffirstpulse := cnt value is:")) Debug.Dec(||timeoffirstpulse) Debug.Tx(13) Debug.Tx(13) 'Debug.Str(string("About to hit the 40 million hz waitcnt in 1st loop",13)) 'waitcnt(ClkFreq/2 + cnt) secondloopcnt := cnt lowhigh1_detected := true if ina[noparse][[/noparse]PulseInputPin] == 0 AND lowhigh1_detected == true highlow1_detected := true Debug.Str(string("lowhigh1_detected and highlow1_detected, entering 2nd loop",13)) repeat if ina[noparse][[/noparse]PulseInputPin] == 1 AND highlow1_detected == true timeofsecondpulse := cnt '(cnt/1000) ' 90 Debug.Str(string("2nd if PulseInputPin == 1 true",13)) Debug.Str(string("timeofsecondpulse := cnt value is:")) Debug.Dec(||timeofsecondpulse) Debug.Tx(13) Debug.Tx(13) 'Debug.Str(string("About to hit the 40 million hz waitcnt in 2nd loop",13)) 'waitcnt(ClkFreq/2 + cnt) thirdloopcnt := cnt lowhigh2_detected := true if ina[noparse][[/noparse]PulseInputPin] == 0 AND lowhigh2_detected == true highlow2_detected := true Debug.Str(string("highlow2_detected, entering 3nd loop",13)) Sigout elseif secondloopcnt =< (- 120_000_000 + cnt) lowhigh2_detected := false Debug.Str(string("2nd loop timeout, quitting",13)) 'waitcnt(ClkFreq/2 + cnt) quit elseif firstloopcnt =< (- 120_000_000 + cnt) lowhigh1_detected := false Debug.Str(string("1st loop timeout, quitting",13)) 'waitcnt(ClkFreq/2 + cnt) next ' **wanted to change this to quit** Pub Sigout repeat if ina[noparse][[/noparse]PulseInputPin] == 1 AND highlow2_detected == true timeoffirstpulse := cnt '(cnt/1000) ' 90 Debug.Str(string("3rd if PulseInputPin == 1 true",13)) Debug.Str(string("timeofsecondpulse := cnt value is:")) Debug.Dec(||timeofsecondpulse) Debug.Tx(13) Debug.Tx(13) 'Debug.Str(string("About to hit the 40 million hz waitcnt in 3rd loop",13)) 'waitcnt(ClkFreq/2 + cnt) Debug.Str(string("Outputting to pin",13)) outa[noparse][[/noparse]OutPutPin] := 1 WaitCnt((ClkFreq / 1000 * fullsec_wait) * 2 + cnt) ' leave output pin set to high for a full second Debug.Str(string("Done outputting to pin",13)) outa[noparse][[/noparse]OutPutPin] := 0 quit elseif thirdloopcnt =< (- 120_000_000 + cnt) Debug.Str(string("3rd loop timeout, quitting",13)) 'waitcnt(ClkFreq/2 + cnt) quitI think it can be done without that kind of indentation, but then we need to better understand what you want the program to do.
My first feeling is, that you only need one repeat loop and the if statements when you introduce a variable which tells you what cycle number you have reached.
Maybe it would be good to use the waitpne and waitpeq instructions to increase accuracy?
What max. and min. pulse/pause times do you expect?
The indents are just the way the IDE did that when I hit the tab button?
I may be able to get away with one repeat loop, but I want the loop to continuously poll (and not pause) which is why I put more than one loop in.
The max time period would be 3 seconds, with at least 1 pulse per second.
I'm really new to spin code and would love to see your logic in how you would code this, if you care to write up an example real quick?
Then the program looks like:
1. setup the counter to count impulses
repeat
2. clear the counter
3. wait or do something usefull for the period
4. check the result and do whatever you want based on the result
For setting up counters you can have a look at the following parallax lab:
http://www.parallax.com/Portals/0/Downloads/appnt/prop/AN001-PropellerCountersv1.2.zip
Post Edited (MagIO2) : 6/22/2010 7:55:18 PM GMT