[MSX-C] Q&A official thread

Check the VDP register values in your favorite emulator and compare with value you are expecting.

try this

#include 
#include 

BOOL skip, scale;
#define TRUE	1		/* constants for BOOL */
#define FALSE	0

TINY smode;

VOID disscr();
VOID enascr();

VOID wait()
{
	char toets='\0';
	while (toets == '\0' )
		{
			if ( kbhit()) {
				toets=chget();
			}

		}
}


VOID display( file )
char *file;

{
    FILE *ptr;
    char buf;
    char *stBuf[256];
    char *cpBuf[128];
    TINY it=1;
    TINY CT=0;
    NAT il=0;
    NAT teller,size, acttel;
    skip = scale = FALSE;

    teller = size = acttel = 0;
    screen((TINY)8);
    di();
    outp(0x99,(TINY)8);
    outp(0x99,(TINY)128+25); /* screen 12 ???*/
    ei();
    if ( (ptr = fopen(file,"rb")) == NULL ) {
        screen((TINY)0);
        puts("Couldn't open file");
        exit(0);
    }
    memset(cpBuf,(char)0,128);
    /* skip header*/
    fread(&buf,1,1,ptr);
    /* skip location in memory*/
    fread(&buf,2,1,ptr);
    disscr();
    setwrt(0);    
    /* read size*/
    fread(&size,2,1,ptr);
    /* go */
    for (teller = 0; teller < size; teller+=256) {
            fread(stBuf,256,1,ptr);
            if ( scale ) {
                for (il=0; il < 256;il++) {
                    if (it == 1) {
                        if (CT < 127) cpBuf[CT] = stBuf[il];
                        it++;
                        CT++;
                    } else {
                        it=1;
                    }
                }
                if (!skip) { 
                    ldirvm(acttel,cpBuf,128);
                }
                if (skip) {
                    skip = FALSE;
                } else {
                    skip = TRUE;
                    acttel+=256;
                }
                it=1;
                CT=0;
        } else {
            ldirvm(teller, stBuf, 256);
        }
    }
    fclose(ptr);
    enascr();
    wait();
    screen((TINY)0);
}


VOID main(argc, argv) 
int argc;
char *argv[];
{
    unsigned teller=0;
    unsigned size=0;
    int c=0;
    smode = 8;

    wrtvdp((TINY)9,(TINY)130);
    wait();
    if ( argc > 0 ) {
        while ( --argc > 0 && (*++argv)[0] == '-' )
		while (c = *++argv[0])
			switch (c) {
				case 's':
					scale = TRUE;
					break;
				case '8':
					smode = 8;
					break;
                case 'c':
                    smode=12;
                    break;
			}
        ginit();
        color ((TINY)15,(TINY)0,(TINY)0);
        printf("loading :%s\n",(*argv));
        display(*argv);    
        exit(0); 
} else
    {
        printf("usage: picview -2 file\n");
        printf(" -2 half size\n");
        exit(0);
    }
}

BL bit is set through function enascr() and disscr(). It is one. The only big problem I have now: the picture loads fine, I can see it, all colours are replaces by shades of green. R#0 0x0E and R#1 0x60. OpenMSX shows that the color palet is not only green. BL stays 1 all the time.

I don't know the details of the MSX-C functions you mention, but if I were in your shoes, I would use the VDP register viewer widget of the openMSX debugger. It shows all the VDP options according to registers bit value and you can change those bits live to see how it affects your rendering. You should start by using the VRAM viewer to see if your graphics data is correct.

If you share your executable, we could help you more easily.

Sadly openmsx debugger doesn't work on newest Mac OS. Crash.