How to put op codes in RAM

[Just Jeff]

Good Morning,

 

Can anyone please tell me a good way to get Dasm to put op codes and operands in RAM?  I'll be running some code there for speed but looking up the op codes and then storing that number seems like it might be more difficult than it has to be.  Best I can think of is defining some op codes as constants and then loading and storing them such as:

 

LDAImmediate     = $A9  ; Load the accumulator with an immediate

 

And then to write lda #20 in the RAM code, my ROM code would be something like:

 

lda #LDAImmediate

sta $80

lda #20

sta $81

 

Is this a decent method or is there something better?

 

[+SpiceWare]

I fixed the code blocks in this blog entry, it might help.

 

 

[+SpiceWare]

Note: I noticed a crucial bit of code was missing - the ROM copy (ZProutineROM) and size calculation (ZPsize).  I added that while you were reading the blog post.

[Just Jeff]

Thanks!  So that looks really straight forward if I understand it correctly.  Like this?:

 

ZProutineRAM    ds 16

    ldy #15
InitZP  
    lda ZProutineROM,y
    sta ZProutineRAM,y
    dey
    bpl InitZP

ZProutineROM:

;read 3 bytes of garbage from here up.  Be careful about the jump to RAM 
;address because it can change.  I think I might use iny and cpy #15 instead.
	lda #SomeNumber		; 2 bytes
	sta SomeRegister	; 2 bytes
	lda ($44,X)		; 6 bytes
	jmp KernelEnd		; 3 bytes

 

[+SpiceWare]

Looks like your code snippet got a bit mangled, the line with lda LDA, but yep that's the idea.

[Just Jeff]

OK yeah I fixed it- Thanks...  And I see the ZPsize too which would eliminate the jmp issue I mentioned.  Though that looks like it can be risky if I don't manage RAM appropriately.

[bogax]

2 hours ago, BNE Jeff said:

Thanks!  So that looks really straight forward if I understand it correctly.  Like this?:

 

ZProutineRAM    ds 16

    ldy #15
InitZP  
    lda ZProutineROM,y
    sta ZProutineRAM,y
    dey
    bpl InitZP

ZProutineROM:

;read 3 bytes of garbage from here up.  Be careful about the jump to RAM 
;address because it can change.  I think I might use iny and cpy #15 instead.
	lda #SomeNumber		; 2 bytes
	sta SomeRegister	; 2 bytes
	lda ($44,X)		; 6 bytes
	jmp KernelEnd		; 3 bytes

 

edit never mind

Edited November 10, 2019 by bogax
I goofed