check boundary conditions properly

[unix-history] / usr / src / lib / libcurses / overlay.c

# include       "curses.ext"
# include       <ctype.h>

# define        min(a,b)        (a < b ? a : b)
# define        max(a,b)        (a < b ? a : b)

/*
*      This routine writes win1 on win2 non-destructively.
*
* %G% (Berkeley) @(#)overlay.c 1.3
*/
overlay(win1, win2)
reg WINDOW      *win1, *win2; {

       reg char        *sp, *end;
       reg int         x, y, endy, endx, starty, startx;

# ifdef DEBUG
       fprintf(outf, "OVERLAY(%0.2o, %0.2o);\n", win1, win2);
# endif
       starty = max(win1->_begy, win2->_begy) - win1->_begy;
       startx = max(win1->_begx, win2->_begx) - win1->_begx;
       endy = min(win1->_maxy, win2->_maxy) - win1->_begy - 1;
       endx = min(win1->_maxx, win2->_maxx) - win1->_begx - 1;
       for (y = starty; y < endy; y++) {
               end = &win1->_y[y][endx];
               x = startx + win1->_begx;
               for (sp = &win1->_y[y][startx]; sp <= end; sp++) {
                       if (!isspace(*sp))
                               mvwaddch(win2, y + win1->_begy, x, *sp);
                       x++;
               }
       }
}