Hi everyone !
I would first like to apologize for my bad English, I'll try to do my best but it's quite hard for me .

So, here is my question/problem : do you know if it is possible to access the saveVram "memory zone".
I explain : during some tests, to optimize drawing, I wanted to compare some pixels with a reference (the background) I have stored before with SaveVRAM_1(); I first tried to do a simple GetPoint routine, but instead of having the VRAM address, I used the saveVram address I founded in the Simon Loathar doc, and confirmed by this topic.
The problem is that I got a System Error everytime I tried this, so, because my routine doesn't look so bad (just from my point of view ), I began to wonder if this sort of memory reading was possible.

Here is the routine I told you :


Code:


I didn't know what address i had to use (0xA80A2AD5 or 0x880A2AD5), I've tried both and got a Sys Error for both. I don't understand a lot the notion of cacheable address, perheaps that's why I got this problems :p.

I believe this is possible because with Insight, we can view this area of memory, but perheaps this isn't accessible for my little skills , but that's why I post here.

So here was my problem, I thank in advance people who read this.
And a bit late "Merry christmas !"

Edit : I tried to correct some sentences, it seems to me that they were not very english.

Hi Nemhardy,

a short pointer mustn't be odd.

0xA80A2AD5 or 0x880A2AD5 can only be considered as char pointer.

Oh, of course, I should have thought of that. Thanks so much for answering, Simon. More generally, a pointer to an integer type of length N bytes must have the bottom log2(N) bits as 0. In other words, a char pointer can be aligned anywhere, a short pointer must be aligned on even addresses, an int pointer must be aligned on pointers that are multiples of 4, and so on.

Thank Simon and Kerm for this answer ! I'm now understanding some things and doing some tests.

Once again thank's a lot !

You're welcome, and glad to hear it. Don't hesitate to post any follow-up questions that you might run into.