Can CogInit only start PASM at ORG 0 ?

Comments

• MagIO2 Posts: 2,243

  2010-06-27 17:39 edited 2010-06-27 17:39

  The address you pass to the coginit tells from where to load the COG-RAM, so the first instruction will be missing and is changing the addresses compared to how it's been compiled.
  
  ORG 0 only tells the compiler where in the code a COG RAM address = 0 is.
  In other words: If you give a different address in the COGINIT/COGNEW than an ORG 0 location, all addresses inside this dat block will be wrong later on in the COG-RAM.
• wjsteele Posts: 697

  2010-06-27 17:54 edited 2010-06-27 17:54

  Should your COGINIT look like this? CogInit(0, @_LMM_JUMP, 0)
  
  Since the second parameter is where you load the ASM from?
  
  Bill
• MagIO2 Posts: 2,243

  2010-06-27 18:30 edited 2010-06-27 18:30

  I suppose your goal is to save runtime and not the 1 long, so how about that:
  
  

    coginit(0, @_LMM_JUMP, 0 )
  
  ....
  
  DAT                                                         
    ORG 0
  _LMM_JUMP         mov           _LMM_JUMP,__readlong
   
  _LMM_LOOP         rdlong        __INSTR1,__PC
                    add           __PC,#4
  
   
  __INSTR1          nop           ' Placeholder for LMM instruction
                    jmp           #_LMM_LOOP
   
  __PC             LONG 0  ' Program counter
   
  _1mSec           LONG 80000
  __temp1          RES 1
  __temp2          RES 1
  __readlong        rdlong         __PC,__PC
  
  
• Cluso99 Posts: 18,071

  2010-06-27 23:04 edited 2010-06-27 23:04

  Bean: As stated, but differently.
  Yes, a cog can only be started at address 0. The address you specify is where in hub the cog data starts from. 496 longs will be loaded from there into the cog and then the cog will start from location 0. You may put a jump there if you wish. The cog code must therefore start at 0 (org 0) otherwise the compiler will use incorrect addresses for the cog when resolving labels. e.g. If you had the start at org $10 then all the jumps would be offset by $10 so the code would crash.
  
  What are you trying to achieve? Perhaps there is another way?
  
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• Bean Posts: 8,129

  2010-06-27 23:07 edited 2010-06-27 23:07

  Okay, I understand now. That address is both the load address AND the execution start address.
  
  Yeah, I'll just put a jump there, I was just not understanding why it didn't work.
  
  I understand now.
  
  Thanks all.
  
  Bean
  
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