FSX The stack in xml-gauges

[Bleedin]

Well, the documentation about the stack in xml gauges is not the best i encunterd...
Could someone give me a example or two how to assign values to the stack?

Can´t find any good examples or tutorials elsewere either. Any tips?

 

[SierraB]

Hehe, that's strange - I was just about to start a new thread about the same problem when your thread popped up!!!

Anyhow, yours first:
I assume you already checked the SDK?
Maybe you find these threads as interesting to read as I did:

http://www.fsdeveloper.com/forum/showthread.php?p=181477#post181477
(scroll down to post 8 following)

http://www.fsdeveloper.com/forum/showthread.php?p=69372#post69372
(also scroll down to post 8 following)

http://www.fsdeveloper.com/forum/showthread.php?p=137276#post137276
(you guess it: scroll down to post 8 following )

Using the stack can be pretty helpful and time saving I realized today


-----------------------

My short question:

This is a part of my helicopter autopilot gauge (the part that controls collective for altitude hold).
My problem is that the value of l11 never gets bigger than 80. To my mind s11 stores the correct value, but l11 then always loads "0".

(A:Vertical SPEED,feet per minute) (L:AP_VS_Var,number) - s12 abs 0 >
      if{ [COLOR="red"]l11[/COLOR] 2 l12 abs 50 / 40 min * l12 l12 abs / * - 14500 min [COLOR="Red"]sp11[/COLOR] }

l11 (>K:THROTTLE_SET)

I already replaced the s11 and l11 by a L:var and it worked fine. But why doesn't this way work??


Cheers,
Steven

 

[EduHir]

Open this link

http://msdn.microsoft.com/en-us/library/cc526953.aspx#mozTocId231151

and search for "Stack operators"

Edi

PS: Sorry, i was not very helpful. Already mentioned above!

 

[taguilo]

My short question:

This is a part of my helicopter autopilot gauge (the part that controls collective for altitude hold).
My problem is that the value of l11 never gets bigger than 80. To my mind s11 stores the correct value, but l11 then always loads "0".

(A:Vertical SPEED,feet per minute) (L:AP_VS_Var,number) - s12 abs 0 >
      if{ [COLOR="red"]l11[/COLOR] 2 l12 abs 50 / 40 min * l12 l12 abs / * - 14500 min [COLOR="Red"]sp11[/COLOR] }

l11 (>K:THROTTLE_SET)

I already replaced the s11 and l11 by a L:var and it worked fine. But why doesn't this way work??

Your formula seems rather difficult to figure out. Bear in mind that in:


if{ l11 2 l12 abs 50 / 40 min * l12 l12 abs / * - 14500 min sp11 }

the whole part in red is processed first, leaving this:

if{ l11 red_result - 14500 min sp11 }

There is no s11 previous to l11, so at gauge load, l11 will be 0.

Also remember that registers (s/l) don't port their values to other gauges, they are local to the current one, as opposite to Lvars. And, because the stack is cleared on every cycle, they are reset to 0 on every cycle as well.

Tom

 

[taguilo]

Could someone give me a example or two how to assign values to the stack?

Sure.

For example

<Update>(A:Vertical SPEED,feet per minute)</Update>

the value contained in (A:Vertical SPEED,feet per minute) is placed on the stack
If it is, for example, 800, then the stack contains 800

Here :
<Update>(A:Vertical SPEED,feet per minute) 500</Update>

The stack contains two values, the var value 800 and 500

Now:
<Update>(A:Vertical SPEED,feet per minute) 500 +</Update>

the stack contais 1300, because the operator + placed at the end automatically performs an addition, leaving the new value and removing the previous operands.

This is the basic principle.

Tom

 

[SierraB]

Hi, Tom!

Yes, the formula is difficult, but it works well

And, because the stack is cleared on every cycle, they are reset to 0 on every cycle as well.

That clears it up. So in fact I cannot use the s/l feature for that code. Then I will simply stick with a L:var.

(And I will check my remaining code with s/l usage.
What a bummer that they refresh!)

Thanks a lot,
Steven

 

[taguilo]

Yeah, they refresh even within the same gauge.

Stream code from <Update> and <Element> shares the stack, so values and registers are kept across.

Event code from <Mouse> and <Keys> refreshes the stack/registers, and values are retained only within a single command (ie <Area>,<On Event>, etc).

Tom

 

[Bleedin]

Thank you for the info

 

[SierraB]

Tom,

your tip about the refreshing stack made me think about a code example from Wozza I found earlier:

 <Update Frequency="6"/>
<Macro Name="Loop">
1 3 5 6 7 10 11 12 14 9 l0 case ( A:SURFACE TYPE,number) ==  if{ 1 sp1 }
</Macro>
<Element>
<Select>
<Value>
 c
 :0 @Loop l0 ++ s0 10 &lt; if{ g0 }
 l1
(A:ENG1 COMBUSTION,number) 0 &gt;
(A:RADIO HEIGHT,meters) 2 &lt;
&amp;&amp; &amp;&amp; if{ (A:SMOKE ENABLE,bool) ! if{ (>K:SMOKE_ON) } } els{ (A:SMO
</Select>
</Element>

Again the l0 is before the s0, but this time in a goto loop.
Does this mean that the current gauge cycle is prevented from completing and thus the stack isn't refreshed?

Steven

 

[taguilo]

In that example the loop is executed within the same gauge cycle.
Within the <Value> command, the stack is first cleared with the c operator, and the registers are all reset to 0. Therefore, in the loop's first pass, l0 equals 0, and starts increasing after the l0 ++ s0 sentence. And the loop will execute while l0 equivalent value is lower than 10 (actually should be 9 &lt; as case's first evaluator is 0).

Tom

 

[Fdd_fr]

Hello,

Sorry to not create a new thread, but I think that is not necessary. I searched on the forum and didn't find information

I am not sure to understand the real difference between s0 and sp0.

So, if somebody can help me to know the difference ?

thanks

François

 

[spokes2112]

Maybe this will help -

CODE              RESULTING STACK     #9 REGISTER (l9)
14 25 s9 36       14 25 36            25
14 25 sp9 36      14 36               25

 

[rpmc]

Also, you can take a look at the examples (especially Example 2) in this Stack Example wiki.

Bob

 

[Fdd_fr]

THanks. I must read this peacefully

I thought that when I store something in register 1 ( Mynumber sp1), the value remained in the register 1 until I set a new number by sp1. I thought that s(n) was like a user variable, but it seems to move permanently.

So, to help me with a simple concrete example, in what case we must use sp0 and not s0 ?


Edit :

sp is to store something, and value not move of stack level with next stack operation. Right ?

So in this case, there is more security to use always "sp" ? isn't it ?

 

[WarpD]

If you use s... you're saying store the value in the register and keep the value on the stack. If you use sp... you're saying store the value in the register and remove it from the stack.

 

[Fdd_fr]

Many thanks Warpd. Your sentence is extremly clear !

 

[tgibson]

I assume that the p stands for Pop, which is a common way to say "remove from the stack".

 

[Au-MaV]

Tom,

your tip about the refreshing stack made me think about a code example from Wozza I found earlier:

 <Update Frequency="6"/>
<Macro Name="Loop">
1 3 5 6 7 10 11 12 14 9 l0 case ( A:SURFACE TYPE,number) ==  if{ 1 sp1 }
</Macro>
<Element>
<Select>
<Value>
c
:0 @Loop l0 ++ s0 10 &lt; if{ g0 }
l1
(A:ENG1 COMBUSTION,number) 0 &gt;
(A:RADIO HEIGHT,meters) 2 &lt;
&amp;&amp; &amp;&amp; if{ (A:SMOKE ENABLE,bool) ! if{ (>K:SMOKE_ON) } } els{ (A:SMO
</Select>
</Element>

Again the l0 is before the s0, but this time in a goto loop.
Does this mean that the current gauge cycle is prevented from completing and thus the stack isn't refreshed?

Steven

LOL actually truth be told it was Tom who came up with the main core of the above code

 

[chris]

Didn't someone do an excel spreadsheet once that could do the xml calculations and display the stack? Or is my memory going?
A quick search for fsx xml excel doesn't bring up anything interesting. ... if only I wasn't so busy...

 

[SierraB]

Didn't someone do an excel spreadsheet once that could do the xml calculations and display the stack? Or is my memory going?
A quick search for fsx xml excel doesn't bring up anything interesting. ... if only I wasn't so busy...

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