Strange variable behaviour

[animo3d]

Hi i found something i can't explain... may be I did something wrong but this is what is happening...

I have a data sctucture as follows:

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Structure Escena
    MaxTime As Byte
    MinTime As Byte
    Actuado As Byte
    NextE As Byte
    Lights(48) As Byte
    ActList(32) As word
End Structure

and an array of these...

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Dim ProgRun(24) As Escena

all was working until i get in a function and odd things happened when tried to assign te values of some of the array to global vars...

with this code can show you:

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   ActEsc=0
   NumAct=4
    For sa = 0 To NumAct-1
      jt=ProgRun(ActEsc).ActList(sa).byte0
      jg=ProgRun(ActEsc).ActList(sa).byte1
      usart2.write("Esc:",dectostr(actesc)," Act:",dectostr(sa), " T:",dectostr(ProgRun(ActEsc).ActList(sa).byte0), " G:",dectostr(ProgRun(ActEsc).ActList(sa).byte1),13,10)
      usart2.write("Esc:",dectostr(actesc)," Act:",dectostr(sa), " T:",dectostr(jt), " G:",dectostr(jg),13,10)
    Next

where jt and jg are global byte vars, and sa is local byte var, and this is trowing this result:

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Esc:0 Act:0 T:0 G:0
Esc:0 Act:0 T:0 G:0
Esc:0 Act:1 T:0 G:0
Esc:0 Act:1 T:32 G:49
Esc:0 Act:2 T:1 G:1
Esc:0 Act:2 T:6 G:16
Esc:0 Act:3 T:1 G:2
Esc:0 Act:3 T:59 G:197

the values on the array are the real ones i put there, but the assigns to JT and JG, get crazy after the first iteration...

I'm really perplexed here...

any Insight will be apreciated...

[Coccoliso]

Hi,
all globals vars are set to 0 and the structure are cleared at the beginning of the program?

[Jerry Messina]

all globals vars are set to 0 and the structure are cleared at the beginning of the program?

No, it's not that. SF doesn't initialize variables at startup... you have to do that yourself if that's what you want.

It looks like it's having a problem with the 'jt = ProgRun(ActEsc).ActList(sa).byte0' syntax. It doesn't always produce the correct address, depending on the usage.
Here's a simple test that shows this:

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device = 18F26K22

include "usart.bas"
include "convert.bas"

Structure Escena
    MaxTime As Byte
    MinTime As Byte
    Actuado As Byte
    NextE As Byte
    Lights(48) As Byte
    ActList(32) As word
End Structure

dim ProgRun(24) as Escena
dim jt as byte
dim jg as byte

dim w as word
dim ix1, ix2 as byte

main:
usart.setbaudrate()

// fill structure array with some values
for ix1 = 0 to 23
    for ix2 = 0 to 31
        ProgRun(ix1).ActList(ix2) = (ix1+1)*256 + (ix2+1)
    next
next

// const array index values...computes these ok
w=ProgRun(0).ActList(1)
jt=ProgRun(0).ActList(1).byte0
jg=ProgRun(0).ActList(1).byte1
// check word vs bytes
if ((w.byte0 <> jt) or (w.byte1 <> jg)) then
    usart.write("not equal", 13, 10)
else
    usart.write("equal", 13, 10)
endif

// variable array index values... not ok
// jt and jg end up with the wrong value
ix1 = 0
ix2 = 1
w=ProgRun(ix1).ActList(ix2)         // w is correct
jt=ProgRun(ix1).ActList(ix2).byte0    // but not these
jg=ProgRun(ix1).ActList(ix2).byte1
// check word vs bytes
if ((w.byte0 <> jt) or (w.byte1 <> jg)) then
    usart.write("not equal", 13, 10)
else
    usart.write("equal", 13, 10)
endif

Both of these should print 'equal', but the second one doesn't.


As a workaround, instead of directly using 'ProgRun(ix1).ActList(ix2).byte0' if you do something like this

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      dim w as word       
      w = ProgRun(ActEsc).ActList(sa)
      jt = w.byte0
      jg = w.byte1

then the values of jt and jg will be correct (plus you'll save a boatload of code)

[animo3d]

Yes Coco and Jerry all the vars are initilized at start...

but that thing you figured not computing tue right address for de array.... Brilliant....

I will try your workaround...

Jerrry, you are the man..!

[animo3d]

Just to let you know....

worked like a charm..!!

Thanks man...!

[David Barker]

Jerry is definitely a SF star! Thanks for that Jerry...