Asynchronous function call in Spin language?

Carvtum · 2010-03-30 13:15

Hi
Is there a way to implement an asynchronous call from one object to another (located in an other Cog) so that the call will return immediately, while the called object starts working with the initiated job parallel with the caller. In other words how do you implement a "fork" with the Spin language?

Sorry, I am new in Spin and could not find an example for this kind of use of the spin language.

pullmoll · 2010-03-30 13:25

Carvtum said...
Hi
Is there a way to implement an asynchronous call from one object to another (located in an other Cog) so that the call will return immediately, while the called object starts working with the initiated job parallel with the caller. In other words how do you implement a "fork" with the Spin language?

Sorry, I am new in Spin and could not find an example for this kind of use of the spin language.

There is an example in the description of either COGINIT or COGNEW.
You can call either with the name of a function and one argument (address) and the address of a stack range to use.

VAR
      long stack[noparse][[/noparse]20]
OBJ
      aobj : "AnObject"

PUB/PRI forking(myparam) | cog
  cog := COGNEW(aobj.myfunc(@myparam), @stack) + 1
  if cog < 1
    do something if failed

The size of the required stack depends on the nesting of subroutines called from the aobj.myfunc function and the number of local variables of each. There is no stack checking, so it's all your job to give it enough room.

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Post Edited (pullmoll) : 3/30/2010 1:31:52 PM GMT

Kye · 2010-03-30 14:38

Mmm, I'm·not sure if·cognew works across objects.

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Nyamekye,

mpark · 2010-03-30 15:33

Kye is correct—you can't cognew methods from another object. The cognew typically is done inside the other object's start pub. You call aObj.start and it does the forking.

Carvtum · 2010-03-31 05:56

OK. Thanks Mpark. I sought out the idea: you have to call such a synchronous method of an other object that in turn launches an other method to run "asynchronously", parallel, as an other "thread" on an other Cog.

ericball · 2010-03-31 15:55

Do be aware that there is a significant startup delay (~8000 CLK cycles) between when COGNEW is executed and when the new code starts executing.

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StefanL38 · 2010-03-31 17:40

cogs and objects are complete different things

you can have ONE object using all eight cogs
or you can have n objects using just one cog and every mixture inbetween.

here is a short democode to show how ONE object can use two cogs and how then the two cogs work independent from each other
manipulating one and the same variable

best regards

Stefan

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000

  
VAR
  long heart_stack[noparse][[/noparse] 20]
  long CogStack1[noparse][[/noparse] 20]
  long CogStack2[noparse][[/noparse] 20]
  
  long MyTestVar

OBJ
  debug : "FullDuplexSerial"


PUB Main
'the FIRST PUB-Method inside a spinfile is ALWAYS the startpoint where the program starts to run
  debug.start(31, 30, 0, 115200)
  
  MyTestVar := 100
  debug.str(string("Start MyTestVar="))
  debug.dec(MyTestVar)
  debug.Tx(13)

  'both cognew-commands are in the SAME file (=same object)
  'in this case you can access variables simply by the variable-name
  cognew(M1,@CogStack1)
  cognew(M2,@CogStack2)
  
  repeat
    waitcnt(clkfreq + cnt)
    debug.str(string("MyTestVar="))
    debug.dec(MyTestVar)
    debug.Tx(13)



PUB M1
  repeat
    waitcnt(ClkFreq * 3 + cnt)
    MyTestVar := 1


PUB M2
  repeat
    waitcnt(ClkFreq * 5 + cnt)
    MyTestVar := 2

Asynchronous function call in Spin language?

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