Xpantastic!

I wasn't very clear about my decompiler and what it does, etc, so I'll 
explain.

Example here:

    http://www.decompiler.org/zol.usub_4BE6.txt [original 6502 code]
    http://www.decompiler.org/zol.usub_4be6.code.txt [decompiled code]

The whole idea is to get rid of all register assignments, and also 
eliminate the use of the stack. Also, it deals with CPU flags.

It does this by having 3 kinds of variable:

    *LLocal (a register used as a loop counter)
    *BLocal (branch local; a register or stack is assigned in an If or 
If/Else block)
    *FLocal (a register or stack is the return value from a function)

Any Global variable, which in most CPUs is just RAM, is not filtered out.

Loops are found, as are any amount of nested If/Else's, and Goto's are 
eliminated. (except for jumps from inside a loop).

The point of my decompiler, then, is not to output code that would 
compile in a C compiler, but to make assembly code much easier to read - 
and much faster to understand. Then you modify the assembly code to do 
what you want.

As an example, I've decompiled a game and I could see what the function 
(which draws the game screen) did, and how it worked, very quickly.

Also, it can output annotated assembly language, and it can output 
addresses before each line of code, so you can load the decompiled code 
into a disassembler, and it shows you the code alongside the code in memory.

As for the 6809, I'll look into getting a disassembler for it and get to 
writing a module.

Cheers,

Jeremy.

@Jeremy

We are waiting for you with a great impatience :-)
Just a question about global variables. They are prefixed with 'Global'. Is the number just after 'Global', the address in the RAM / IO space ?

Hi Jeremy,

Yes, that looks great. The indentation alone is a massive help. Is that some sort of VB-like format it's generating? Can you output a more abstract, structured format (e.g. in XML)?

We're drifting somewhat off-topic for this list, so feel free to email me privately if you like.

Cheers,

John :^P  

On Tuesday, 3 April 2012 at 16:52, Jeremy Smith wrote:

>  
> I wasn't very clear about my decompiler and what it does, etc, so I'll  
> explain.
>  
> Example here:
>  
> http://www.decompiler.org/zol.usub_4BE6.txt [original 6502 code]
> http://www.decompiler.org/zol.usub_4be6.code.txt [decompiled code]
>  
> The whole idea is to get rid of all register assignments, and also  
> eliminate the use of the stack. Also, it deals with CPU flags.
>  
> It does this by having 3 kinds of variable:
>  
> *LLocal (a register used as a loop counter)
> *BLocal (branch local; a register or stack is assigned in an If or  
> If/Else block)
> *FLocal (a register or stack is the return value from a function)
>  
> Any Global variable, which in most CPUs is just RAM, is not filtered out.
>  
> Loops are found, as are any amount of nested If/Else's, and Goto's are  
> eliminated. (except for jumps from inside a loop).
>  
> The point of my decompiler, then, is not to output code that would  
> compile in a C compiler, but to make assembly code much easier to read -  
> and much faster to understand. Then you modify the assembly code to do  
> what you want.
>  
> As an example, I've decompiled a game and I could see what the function  
> (which draws the game screen) did, and how it worked, very quickly.
>  
> Also, it can output annotated assembly language, and it can output  
> addresses before each line of code, so you can load the decompiled code  
> into a disassembler, and it shows you the code alongside the code in memory.
>  
> As for the 6809, I'll look into getting a disassembler for it and get to  
> writing a module.
>  
> Cheers,
>  
> Jeremy.
>  
>

Do It Yourself Synth wrote:

>@Jeremy
>
>We are waiting for you with a great impatience :-)
>  
>
I'm onto it!;-)

>Just a question about global variables. They are prefixed with 'Global'. Is the number just after 'Global', the address in the RAM / IO space ?
>  
>
Yes.

Sometimes a pair of Globals (hi/lo bytes) are converted into a single 
16-bit word.

Also, I had 'ram[200]' at first but preferred the 'Global200' syntax.

Of course, however you want to display the RAM/IO address access is up 
to you.

Cheers,

Jeremy.