Gameboy Development Forum

Hi. Have you tried mode(M_TEXT_OUT); ?

According to the GBDK 2020 manual:

"APA Graphics Mode: When this mode is used (via drawing.h) custom VBL and LCD ISRs handlers will be installed ( drawing_vbl and drawing_lcd ). Changing the mode to ( mode(M_TEXT_OUT); ) will cause them to be de-installed. These handlers are used to change the tile data source at start-of-frame and mid-frame so that 384 background tiles can be used instead of the typical 256."

I wish I could be more help for you, but I'm also new to programming for the Game Boy and have little experience with APA mode. You probably know more about that than I do right now.

The thought occurred to me that you could probably do

void(*p)(void)=0x1a89;
remove_LCD(p);

to remove an interrupt handler if the address wouldn't change. But it does change.

The remove_LCD(drawing_lcd) and remove_VBL(drawing_vbl) might not work because I think the compiler prepends a '_', so drawing_lcd in C becomes _drawing_lcd in assembly. Maybe you could use inline assembly to do that. Or maybe there's a better solution that I don't know about.

I tried switching out of APA mode from one of my APA test programs that I had started as a pong game, and I had problems too.

But when I add the following lines just before the infinite loop in the main of the apa_image example, it seems to work fine. So if all you want to do is show a full screen splash image, maybe try using that example with this code as a template (at gbdk/examples/gb/apa_image/src).

delay(500);
mode(M_TEXT_OUT);
for(uint8_t y=0;y<16;++y){
 gotoxy(6,y);
 printf("Hello #%d\n",y);
}

Yes, changing the mode will allow it to exit APA.

Scroll down a little from the top of the docs page for drawing.h:
https://gbdk-2020.github.io/gbdk-2020/d … ng_8h.html

Note: Using drawing.h will cause it's custom VBL and LCD ISRs (drawing_vbl and drawing_lcd) to be installed.
Changing the mode (mode(M_TEXT_OUT); ) will cause them to be de-installed.

Perhaps Toxa knows a better way to do it (other than writing a version in asm source file), but this might work:

    // Turn off LCD Interrupt
    // This disables and then re-enables interrupts so it must be outside the critical section.
    set_interrupts(IE_REG & ~LCD_IFLAG);

    // Remove the two APA interrupt routines
    // Turn off LCD Interrupt
    // This disables and then re-enables interrupts so it must be outside the critical section.
    set_interrupts(IE_REG & ~LCD_IFLAG);

    // Remove the two APA interrupt routines (with interrupts turned off)
    CRITICAL {
        __asm \
            push BC
            push HL
            LD      BC, #.drawing_vbl
            LD      HL, #.int_0x40
            CALL    .remove_int

            LD      BC, #.drawing_lcd
            LD      HL, #.int_0x48
            CALL    .remove_int
            pop HL
            pop BC
        __endasm;
    }

Last edited by bbbbbr (2023-01-09 23:47:14)

@bbbbbr WOW ! Great ! Works !
Many thanks ... Perhaps people at GBDK should add this method to their lib for beginers like me ...

Hi,

I search a way to exit APA mode too. I have used drawing.h and draw_image(). But I don't have good result to get out of this mode for simply drawing sprite and background tiles like in start of a game.

I have something simple here but I don't know Why I need to put printf(" "); (with a space character for make it work).

void disable_APA(void){
    DISPLAY_OFF;
    mode(M_TEXT_OUT); 
    printf(" ");
    DISPLAY_ON;
}

That can be done also with:

void disable_APA(void){
    DISPLAY_OFF;
    mode(M_TEXT_OUT); 
    putchar(' ');
}

After it make routines for load BKG and SPRITES and show it. If someones can explain me why somes sprites stay on memory when I don't use printf(" "); or putchar(' '); ?

Here is the result in video:
APA Mode to Tile Mode

Last edited by Kitsune64 (2023-11-03 16:18:28)