Problem at startup on MorphOS platform

[papiosaur]

Hello,

i'm porting a2m on MorphOS but i have some trouble at startup. A screen with bizarre characters and CPU high.

An endian issue maybe? MorphOS is big endian.

Thanks for you return.

[StewBC]

Hi,

This sounds cool! I wish I had a PPC machine, then I could really help.

Since it doesn't sound like it crashed, I would think it's maybe a drawing issue? Maybe start by checking if int bpp = surface->format->BytesPerPixel; is 4. I assume that in the drawing code, and it may be aligned in some other way. Then everything will be off.

Somthing like this for the text case (how the emulator boots up) addresses that, also locks the surface, maps the colours to the surface, etc. This works on Windows and it's worth a test to see if it fixes anything on Morph OS.

void viewapl2_screen_txt(APPLE2 *m, int start, int end) {
SDL_Surface *surface = m->viewport->surface;
if (SDL_MUSTLOCK(surface)) SDL_LockSurface(surface);

uint8_t *base = (uint8_t*)surface->pixels;
const int bpp = surface->format->BytesPerPixel;
const int pitch_px = surface->pitch / bpp;
uint32_t c[2] = {
    SDL_MapRGB(surface->format, 0,0,0),
    SDL_MapRGB(surface->format, 255,255,255)
};
int page = m->viewport->shadow_active_page ? 0x0800 : 0x0400;

for (int y = start; y < end; y++) {
    uint32_t *p = (uint32_t*)(base + (y * 8) * surface->pitch);
    int address = page + txt_row_start[y];

    for (int x = 0; x < 40; x++) {
        uint32_t *pr = p;
        int character = m->RAM_MAIN[address + x];
        uint8_t inv = (~character >> 7) & 1;
        uint8_t *glyph = &m->roms.blocks[ROM_CHARACTER].bytes[character * 8];

        for (int r = 0; r < 8; r++) {
            uint8_t bits = *glyph++;
            for (int i = 6; i >= 0; i--) {
                pr[i] = c[inv ^ (bits & 1)];
                bits >>= 1;
            }
            pr = (uint32_t*)((uint8_t*)pr + surface->pitch);   // step one scanline
        }
        p += 7;   // next 7-pixel cell horizontally
    }
}
if (SDL_MUSTLOCK(surface)) SDL_UnlockSurface(surface);

}

Also try this in viewport.c, viewport_init

This clears the surface after creating it with SDL pixel format flags, not my method.

// Create RGB surface
v->surface = SDL_CreateRGBSurfaceWithFormat(0, 40*7, 24*8, 32, SDL_PIXELFORMAT_ARGB8888);
if(v->surface == NULL) {
    printf("Surface could not be created! SDL_Error: %s\n", SDL_GetError());
    goto error;
}
SDL_FillRect(v->surface, NULL, SDL_MapRGB(v->surface->format, 0,0,0));

v->surface640 = SDL_CreateRGBSurfaceWithFormat(0, 80*8, 24*8, 32, SDL_PIXELFORMAT_ARGB8888);
if(v->surface640 == NULL) {
    printf("Surface640 could not be created! SDL_Error: %s\n", SDL_GetError());
    goto error;
}
SDL_FillRect(v->surface640, NULL, SDL_MapRGB(v->surface640->format, 0,0,0));

---

Apparently this is a "sane" command line for Morph OS when doing a port like this:
-fsigned-char -fno-strict-aliasing -O2 -g -Wall -Wextra -Wcast-align

Did you hear the Apple II beep at startup? You can also email me directly (swessels@email.com) if you want to, I'd be happy to try and help. Wish I could run Morph OS though!

Last thought - This: https://github.com/StewBC/mminer-apple2/tree/master/src/mmm was a stepping stone to building a2m. I am not sure it makes a big difference, but it might be easier to get that working, and take what was learnt there and fix a2m.

Stefan