lda #(^VRAM_addr + 2) ?

[Dacobi]

Hi 

I'm trying to port some code to C and I've got most of it working.

But I don't understand the (^ADDRESS + 2) syntax. What does it do? and what would it be in C?

The code where it's used is for the address and bank.

If I just use  cbm_k_load(2, address);  it doesn't work.

[Greg King]

On 12/27/2021 at 3:29 PM, JimmyDansbo said:

I would think that it should be cbm_k_load((address+2)>>16, address)

No, the addition must be done last.  It's used to move past numbers that Commodore already used to control Kernal's LOAD behavior:

• 0 -> normal load
• 1 -> normal verify

• 2 -> VRAM address high bit (0)
• 3 -> VRAM address high bit (1)

[JimmyDansbo]

Just like < and > gives you the low- and high- byte of a constant, ^ gives you the bank.

The manual for CA65 has a bit of information.

https://cc65.github.io/doc/ca65.html#ss5.5

[Dacobi]

On 12/27/2021 at 8:23 PM, JimmyDansbo said:

Just like < and > gives you the low- and high- byte of a constant, ^ gives you the bank

So in C that would be cbm_k_load((address>>16)+2, address) ?

[JimmyDansbo]

I would think that it should be cbm_k_load((address+2)>>16, address)