source: buchla-68k/vlib/vtext.c@ c65a0e2

/*
   =============================================================================
        vtext.c -- output a text string to the VSDD in 1 byte / character mode
        Version 3 -- 1987-06-02 -- D.N. Lynx Crowe

        Assumes VSDD is pointing at bank 0.
   =============================================================================
*/

static int      msk[] = { 0xFF00, 0x00FF };

vtext(obj, nc, row, col, ip)
register unsigned *obj, nc, row, col;
register char *ip;
{
        register unsigned *op;

        while (*ip) {

                op = obj + ((nc >> 1) * row) + (col >> 1);

                *op = (*op & (unsigned)msk[col & 1]) |
                      ((*ip++ & 0x00FF) << ((col & 1) ? 8 : 0));

                col++;
        }
}