assembly question

basil99 · **Joined:** Thu Mar 10, 2011 12:18 pm **Posts:** 6

Hi!
Have this simple assembly code in my PB programm

Code:

      EnableASM

      PUSHAD
      
      MOV esi, S
      MOV edi, D
      MOV ecx, DrawWidth
      
FDloop:

      MOV eax, [esi]
      ADD esi, 4
      MOV [edi], eax
      ADD edi, 4
      DEC ecx
      JNZ FDloop

      POPAD

      DisableASM

try to compile and get this error messge:

Purebasic assembler error: JNZ FDloop error : undefined symbol 'FDloop'.

Whats wrong here ? any ideas ? Plese point my stupid head )
Thanks

J. Baker · **Posted:** Sun Jul 01, 2012 9:37 am

!FDloop:

wilbert · **Posted:** Sun Jul 01, 2012 12:44 pm

JNZ l_fdloop

Is also a possibility

Quote:

When you reference a label, you must put the prefix 'l_' before the name. This is because PureBasic add a 'l_' before a BASIC label to avoid conflit with internal labels. The label need to be referenced in lowercase when using the inlined ASM.

basil99 · **Joined:** Thu Mar 10, 2011 12:18 pm **Posts:** 6

Thanks for replies.

l_FDloop don't work, but !FDloop does.
Anyway, I need further assistance.
This assembly code:

Code:

EnableASM

      PUSHAD
      
      MOV esi, S
      MOV edi, D
      MOV ecx, DrawWidth
      
!FDloop:

      MOV eax, [esi]
      ADD esi, 4
      MOV [edi], eax
      ADD edi, 4
      DEC ecx
      JNZ FDloop

      POPAD

      DisableASM

planned to be the assembly version of this PB code, that works fine:

Code:

      For x = 1 To DrawWidth

         B = PeekI( S )
         S = S + 4
         PokeI( D, B )
         D = D + 4

      next x

So, PB code works, Assembly code crashed. Whats wrong ? Thanks

Thorium · **Joined:** Sat Aug 15, 2009 6:59 pm **Posts:** 1024

If your code is in a procedure you mess up the stack index of the local variables with pushad. Thats why it crashes.

Try this:

Code:

!push esi
!push edi

!mov esi, [p.v_S+8]
!mov edi, [p.v_D+8]
!mov ecx, [p.v_DrawWidth+8]

!FDloop:
  !mov eax, [esi]
  !add esi, 4
  !mov [edi], eax
  !add edi, 4
  !dec ecx
!jnz FDLoop

!pop edi
!pop esi

basil99 · **Joined:** Thu Mar 10, 2011 12:18 pm **Posts:** 6

Thorium wrote:

If your code is in a procedure you mess up the stack index of the local variables with pushad. Thats why it crashes.

Try this:

Code:

!push esi
!push edi

!mov esi, [p.v_S+8]
!mov edi, [p.v_D+8]
!mov ecx, [p.v_DrawWidth+8]

!FDloop:
  !mov eax, [esi]
  !add esi, 4
  !mov [edi], eax
  !add edi, 4
  !dec ecx
!jnz FDLoop

!pop edi
!pop esi

Thanks, Thorium, tried it and get this error message:

!mov esi, [p.v_S+8] - error: undefined symbol 'p.v_S+8'

as for code, don't catch what you mean with "procedure". Code skeleton looks like this:

Code:

S1 = Calculate( S1 )
D1 = Calculate( D1 )
DrawWidth = Calculate( DrawWidth )
DrawHeight = Calculate( DrawHeight )
Sstep = Calculate( Sstep )
Dstep = Calculate( Dstep )

for y = 1 to DrawHeight

    S = S1
    D = D1

    for x = 1 to DrawWidth

                    Code, we're talking about

     next x

     S = S + Sstep
     D = D + Dstep

next y

sure, its a part of a procedure for a DLL i try to code )

wilbert · **Posted:** Mon Jul 02, 2012 10:56 am

Code:

EnableASM

      MOV eax, S
      MOV edx, D
      MOV ecx, DrawWidth

      PUSH ebx      

!FDloop:

      MOV ebx, [eax]
      ADD eax, 4
      MOV [edx], ebx
      ADD edx, 4
      DEC ecx
      JNZ FDloop

      POP ebx

      DisableASM

Thorium · **Joined:** Sat Aug 15, 2009 6:59 pm **Posts:** 1024

basil99 wrote:

Thanks, Thorium, tried it and get this error message:

!mov esi, [p.v_S+8] - error: undefined symbol 'p.v_S+8'

as for code, don't catch what you mean with "procedure". Code skeleton looks like this:

The undefined symbol is actualy without the +8 and means it's a global variable. for global variables use only v_ not p.v_, p.v_ is only for local variables.

With procedure i mean if the code is located inside a procedure and uses local variables. Because local variables are on the stack, the stack index for them shifts if you push something to the stack. So you must add the number of bytes to the variable pointer that was been pushed to the stack.

basil99 · **Joined:** Thu Mar 10, 2011 12:18 pm **Posts:** 6

Stiil confused (
Seems, need to explain more clear what i'm doing.

1. Third party code prepares a raw RGBA image ( actually BGRA ). I know image adress, image Width and Height, and image Pitch = len of one pixels line. Pitch in general is not equal to Width*4. Also, a destination adress is known, where i need to put "processed" image.

2. So, I decide to create a DLL for this, that would make all this job. Fiest step is just to copy source data into destination. Processing is another step, not significant to talk about here

3. Dll code is:

Code:

ProcedureDLL ImageProcessing(  Width, Height, SourceAdress, DestAdress, Pitch )

S1 = SourceAdress
D1 = DesrAdress
DrawWidth = Width
DrawHeight = Height
Sstep = Pitch
Dstep = Pitch

for y = 1 to DrawHeight

    S = S1
    D = D1

    for x = 1 to DrawWidth

                B = PeekI( S )
         S = S + 4
         PokeI( D, B )
         D = D + 4


     next x

     S = S + Sstep
     D = D + Dstep

next y



EndProcedure

and this works perfect. But asembly not (

Thorium · **Joined:** Sat Aug 15, 2009 6:59 pm **Posts:** 1024

Dont know how i should explain it differently.

But as i wrote, this works:

Code:

ProcedureDLL ImageProcessing(  Width, Height, SourceAdress, DestAdress, Pitch )

S1 = SourceAdress
D1 = DesrAdress
DrawWidth = Width
DrawHeight = Height
Sstep = Pitch
Dstep = Pitch

For y = 1 To DrawHeight

    S = S1
    D = D1

    !push esi
    !push edi
    
    !mov esi, [p.v_S+8]
    !mov edi, [p.v_D+8]
    !mov ecx, [p.v_DrawWidth+8]
    
    !FDLoop:
      !mov eax, [esi]
      !add esi, 4
      !mov [edi], eax
      !add edi, 4
      !dec ecx
    !jnz FDLoop
    
    !pop edi
    !pop esi

     S = S + Sstep
     D = D + Dstep

Next y

EndProcedure

basil99 · **Joined:** Thu Mar 10, 2011 12:18 pm **Posts:** 6

Great ! It works.
and I need to learn syntax better.
Thanks a lot for this

Pupil · **Joined:** Fri Apr 25, 2003 3:56 pm **Posts:** 715

If you're only moving data from one place to another, why not use the built in 'CopyMemory()' function instead?

If pitch is same for source and destination I think something like this would work OK:

Code:

CopyMemory(SourceAdress, DestAdress, (width*4+pitch)*height)

basil99 · **Joined:** Thu Mar 10, 2011 12:18 pm **Posts:** 6

Pupil wrote:

If you're only moving data from one place to another, why not use the built in 'CopyMemory()' function instead?

If pitch is same for source and destination I think something like this would work OK:

Code:

CopyMemory(SourceAdress, DestAdress, (width*4+pitch)*height)

Good idea, mate. I have smth more complex to do:

1) I need to make some operations with source image, like filter, effects etc

2) destination area may be an another image, smaller or bigger or equal then source one. So, some clipping is required ( omitted here )

3) Quick timing brings me the following : asm vesion 2.5-3 times faster then native PB peek/poke )

Psychophanta · **Posted:** Thu Jul 05, 2012 5:03 pm

PB does allow to define variables, but does not allow to define labels inside a EnableASM-DisableASM block.
This looks like a clear bug to me.

ultralazor · **Joined:** Sun Jun 27, 2010 9:00 am **Posts:** 186

Even better.. why not just use PB? Maybe for your users sake since you don't know how a stack frame works?

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