Reclaiming DAT space?

mpark

It seems to me that after I send my assembly language DAT code to the various cogs, it's just taking up valuable hub memory. I need 12k contiguous bytes for screen memory and I'm getting dangerously close to running out of memory. Is there some way to arrange for my assembly code to be next to some large buffer space so that I can use the buffer and the DAT space together as one contiguous memory space?

Paul Baker

Yes, if you do not need to reload the assembly, this is no problem with overwriting the DAT section

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

mpark

But how do I know where the DAT section resides in the hub? And how do I ensure it's next to a sufficiently large area of free memory? E.g. Suppose I need 12kbytes contiguous, but I only have 10k free, but I have 2k of assembly that I can overwrite. How do I arrange things so that the 10k is next to the 2k?

Paul Baker

You declare it as such, IOW you put the assembly right before the declared buffer then use the assembly's label.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

deSilva

Maybe it is too straightforward? This is one example of many:

DAT
  org 0
theBuffer
theASM
    NOP
    NOP
theEnd
    LONG 0[noparse][[/noparse]512- (theEnd-theASM)]

Note that assembly labels count COG cells , not "bytes"

Post Edited (deSilva) : 8/28/2007 4:34:23 PM GMT

Phil Pilgrim (PhiPi)

I think you might want to put the ORG 0 after theBuffer, so the assembly begins at cog address 0. This will not affect the hub address of either theBuffer or theASM.

-Phil

mpark

Thanks all, esp. deSilva. Allocating the buffer in DAT space was indeed too straightforward. I was complicating things in my mind, thinking I'd have to align DAT space and unallocated space somehow. Duh.

mpark

A further wrinkle: If I have assembly in several objects, is there a way to get all their DAT sections next to each other so I can reuse them all as one big block?

Paul Baker

No

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

deSilva

When you compile appropriate code, press F8 and look at the colorful memory map, you will see, it does not work DAT is handeled nearly identical to PUB/PRI code, which was to be expected...

obj
  N2 : "n2"
PUB N1
 return 1
 return 2
 return 3
 return 4
 return 5
 return 6
 return 7
 return 8
DAT
 NN1 long $11111111[noparse][[/noparse]10]  

PUB N2
 return 1
 return 2
 return 3
 return 4
 return 5
 return 6
 return 7
 return 8
DAT
 NN2 long $22222222[noparse][[/noparse]10]

Phil Pilgrim (PhiPi)

I've reread this thread, since it was linked to in a more recent thread. There's no reason you can't combine all your assembly code from several objects into one long DAT section, thus:

'' Top object

CON

  _clkmode      = xtal1 + pll16x
  _xinfreq      = 5_000_000

OBJ

  myobj : "my_object"

PUB  start

  myobj.start(@myobjasm)
  cognew(@mylocalasm, 0)

DAT

              org       0
mylocalasm    mov       dira,#1
:loop         mov       outa,#1
              mov       outa,#0
              jmp       #:loop

              org       0
myobjasm      mov       dira,#2
:loop         mov       outa,#2
              nop
              mov       outa,#0
              jmp       #:loop

''___________________________________________

'' my_object.spin (separate file)

PUB start(asmaddr)

  cognew(asmaddr, 0)

It's not exactly what you'd call "object encapsulation" but it does force all the assembly code into one contiguous block.

-Phil

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'Still some PropSTICK Kit bare PCBs left!

mpark

Where were you when I needed this last year?!

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Michael Park

PS, BTW, and FYI:
To search the forum, use search.parallax.com (do not use the Search button).
Check out the Propeller Wiki: propeller.wikispaces.com/

Rayman

For a second, I though deSilva was back [noparse]:)[/noparse] Then, I saw it was last year...

simonl

@Rayman: Me too!

@deSilva: You're still missed

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Cheers,

Simon

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