fixed wrap around problem

[unix-history] / usr / src / usr.bin / window / wwscroll.c

#ifndef lint
static  char *sccsid = "@(#)wwscroll.c  3.3 83/08/16";
#endif

#include "ww.h"
#include "tt.h"

/*
* Scroll down one line, starting at 'line'.
* Don't adjust ww_scroll.
*/
wwscroll1(w, srow, erow, dir, leaveit)
register struct ww *w;
int srow, erow, dir;
char leaveit;
{
       register i;
       int startrow, endrow;
       int nvis;
       int nvismax;
       int deleted = 0;

       /*
        * See how many lines on the screen are affected.
        * And calculate srow, erow, and left at the same time.
        */
       for (i = srow; i <= erow && w->ww_nvis[i] == 0; i++)
               ;
       if ((startrow = i) > erow) {
               /* can't do any fancy stuff */
               endrow = startrow - 1;
               goto out;
       }
       for (i = erow; i >= srow && w->ww_nvis[i] == 0; i--)
               ;
       if ((endrow = i) == startrow)
               goto out;               /* just one line is easy */

       /*
        * See how much of this window is visible.
        */
       nvismax = wwncol * (endrow - startrow + 1);
       nvis = 0;
       for (i = startrow; i <= endrow; i++)
               nvis += w->ww_nvis[i];

       /*
        * If it's a good idea to use delete and insert line
        * and the terminal can, then do it.
        */
       if (nvis > nvismax / 2 && tt.tt_delline && tt.tt_insline) {
               register union ww_char *tmp;
               register union ww_char **cpp, **cqq;

               if (dir > 0) {
                       (*tt.tt_move)(startrow + w->ww_w.t, 0);
                       (*tt.tt_delline)();
                       if (endrow + w->ww_w.t != wwnrow - 1) {
                               (*tt.tt_move)(endrow + w->ww_w.t, 0);
                               (*tt.tt_insline)();
                       }
                       /*
                        * Fix up the old screen.
                        */
                       cpp = &wwos[startrow + w->ww_w.t];
                       cqq = cpp + 1;
                       tmp = *cpp;
                       for (i = endrow - startrow; --i >= 0;)
                               *cpp++ = *cqq++;
                       *cpp = tmp;
                       for (i = wwncol; --i >= 0;)
                               tmp++->c_w = ' ';
               } else {
                       if (endrow + w->ww_w.t != wwnrow - 1) {
                               (*tt.tt_move)(endrow + w->ww_w.t, 0);
                               (*tt.tt_delline)();
                       }
                       (*tt.tt_move)(startrow + w->ww_w.t, 0);
                       (*tt.tt_insline)();
                       /*
                        * Fix up the old screen.
                        */
                       cqq = &wwos[endrow + w->ww_w.t];
                       cpp = cqq + 1;
                       tmp = *cqq;
                       for (i = endrow - startrow; --i >= 0;)
                               *--cpp = *--cqq;
                       *cqq = tmp;
                       for (i = wwncol; --i >= 0;)
                               tmp++->c_w = ' ';
               }
               deleted++;
       }

       /*
        * Fix the new screen.
        */
       if (nvis == nvismax) {
               /*
                * Can shift whole lines.
                */
               if (dir > 0) {
                       {
                               register union ww_char *tmp;
                               register union ww_char **cpp, **cqq;

                               cpp = &wwns[startrow + w->ww_w.t];
                               cqq = cpp + 1;
                               tmp = *cpp;
                               for (i = endrow - startrow; --i >= 0;)
                                       *cpp++ = *cqq++;
                               *cpp = tmp;
                       }
                       {
                               register char *p, *q;

                               p = &wwtouched[startrow + w->ww_w.t];
                               q = p + 1;
                               for (i = endrow - startrow; --i >= 0;)
                                       *p++ = *q++;
                               *p = 1;
                       }
                       wwredrawwin1(w, srow, startrow - 1, w->ww_scroll + dir);
                       wwredrawwin1(w, endrow + 1, erow - leaveit,
                               w->ww_scroll + dir);
               } else {
                       {
                               register union ww_char *tmp;
                               register union ww_char **cpp, **cqq;

                               cqq = &wwns[endrow + w->ww_w.t];
                               cpp = cqq + 1;
                               tmp = *cqq;
                               for (i = endrow - startrow; --i >= 0;)
                                       *--cpp = *--cqq;
                               *cqq = tmp;
                       }
                       {
                               register char *p, *q;

                               q = &wwtouched[endrow + w->ww_w.t];
                               p = q + 1;
                               for (i = endrow - startrow; --i >= 0;)
                                       *--p = *--q;
                               *q = 1;
                       }
                       wwredrawwin1(w, srow + leaveit, startrow - 1,
                               w->ww_scroll + dir);
                       wwredrawwin1(w, endrow + 1, erow, w->ww_scroll + dir);
               }
       } else {
out:
               if (dir > 0)
                       wwredrawwin1(w, srow, erow - leaveit,
                               w->ww_scroll + dir);
               else
                       wwredrawwin1(w, srow + leaveit, erow,
                               w->ww_scroll + dir);
       }
       return deleted;
}