Prog8 language and compiler topic

[hstubbs3]

Funkheld

6502 CPU only has few registers... Accumulator (often called A), X and Y.. each is 1 byte - 0 to 255..
Multiple instructions allow indexing into memory using X or Y register ...

Actually, I gave some example of that in the other forum post, where you had asked about prog8 to save/load the current screen..

This bit here - uses X as a counter to track pages, y to index each byte of the page, and ZeroPage_PTR is 2 consecutive bytes in zero page of RAM ( $0000-$00FF ) set to some address like $HH00... the start of a page of memory..

LDX #num_pages
LDY #0
:
: LDA DATA0
STA (ZeroPage_PTR),y
iny
BNE :-
INC ZeroPage_PTR+1 ; this bit right here or you'll only keep overwriting that first page you're trying to write too.
DEX
BNE ;--


random index into array > 256 requires altering the highbyte... one _could_ create an array of arrays to manage the high byte themselves... IE say for 60 lines on screen, make an array sized 120 (60*2 bytes) to hold pointers to arrays with 160 bytes each (80 characters across the screen, char code + color data )

Then ... what line do you want? ... say 31... double it => 64 ... get bytes 64 and 65 into your pointer / memory address ... that would be the array to index for the other data ..

or if the arrays always start at beginning of page, would only need 1 byte for the first array, and access via the setting some ZP to $HH00 to index... but in this example, that would waste 96 bytes per line in memory...

(that bit -might- be more for desertfish to consider supporting a '2d' array of X pages... maybe in a way to span banks??? they are writing a compiler alone... it may be a bit much to ask )


I had provided some code for saving/loading the screen - maybe someone here could fill in the vars and such I wasn't sure on??

viewtopic.php?t=7266

sub screensave() {
ubyte *SAVEDSCREEN $someaddress_in_RAM ; // set the pointer here
for y1 in 0 to 60 {
cx16.vaddr_autoincr(1, VERA_TXTSCREEN + y1*$0100, 0, 2)
for x1 in 0 to 79 {
*SAVEDSCREEN = cx16.VERA_DATA0;
SAVEDSCREEN++;
}
}
}

sub screenload() {
ubyte *SAVEDSCREEN = $someaddress_in_RAM ; // set the pointer here
for y1 in 0 to 60 {
cx16.vaddr_autoincr(1, VERA_TXTSCREEN + y1*$0100, 0, 2)
for x1 in 0 to 79 {
cx16.VERA_DATA0 = *SAVEDSCREEN ;
SAVEDSCREEN++;
}
}
}

[funkheld]

Hello, thank you very much for the quick information.

Now I'm going to go to sleep and I'll work on it tomorrow.

Thank you.
greeting

[desertfish]

Prog8 version 10.2 has been released

https://github.com/irmen/prog8/releases/tag/v10.2

The most important change is that the compiler now treats booleans much stricter than before. No longer 'equivalent' to a byte 0 or 1. You'll need an explicit cast to convert between bytes and booleans now.

If you are using conditionals like "if integervariable {....}" you'll have to make it into a boolean comparison expression like so "if integervariable!=0 {....}" .

For all the gory details read the release notes on the github release page.

[funkheld]

hello, thank you for version 10.2

What a great job you're doing, great.



Thanks.
greeting

[desertfish]

Prog8 version 10.2.1 is released https://github.com/irmen/prog8/releases/tag/v10.2.1

Unfortunately a rather severe error was found after the 10.2 release, in the code generator for logical expressions (and/or). This is now fixed.

PS the error was already present since version 10.0, just not discovered until now...

[funkheld]

hello thanks for info.

greeting

[desertfish]

Prog8 version 10.3 has been released: https://github.com/irmen/prog8/releases/tag/v10.3

There's a change in this version that's not backwards compatible with older code, so it may be required to make some simple changes:

It is now possible (and required) to assign all values returned from a romsub/asmsub that returns multiple values.
The void keyword can now also be used in a new way: as a dummy assignment target for any value you are not interested in in such a multi-value assignment.

Please read the documentation in the manual for details about this new feature: https://prog8.readthedocs.io/en/latest/ ... ultiassign

[funkheld]

hello, thank you for the new version.

greeting

[BrokenAnsible]

This is such a great project. Thank you!