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-rw-r--r--lib/libcurses/refresh.c723
1 files changed, 723 insertions, 0 deletions
diff --git a/lib/libcurses/refresh.c b/lib/libcurses/refresh.c
new file mode 100644
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--- /dev/null
+++ b/lib/libcurses/refresh.c
@@ -0,0 +1,723 @@
+/*
+ * Copyright (c) 1981, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)refresh.c 8.1 (Berkeley) 7/20/93";
+#endif /* not lint */
+
+#include <curses.h>
+#include <string.h>
+
+static int curwin;
+static short ly, lx;
+
+static void domvcur __P((int, int, int, int));
+static int makech __P((WINDOW *, int));
+static void quickch __P((WINDOW *));
+static void scrolln __P((WINDOW *, int, int, int, int, int));
+
+/*
+ * wrefresh --
+ * Make the current screen look like "win" over the area coverd by
+ * win.
+ */
+int
+wrefresh(win)
+ register WINDOW *win;
+{
+ register __LINE *wlp;
+ register int retval;
+ register short wy;
+ int dnum;
+
+ /* Initialize loop parameters. */
+ ly = curscr->cury;
+ lx = curscr->curx;
+ wy = 0;
+ curwin = (win == curscr);
+
+ if (!curwin)
+ for (wy = 0; wy < win->maxy; wy++) {
+ wlp = win->lines[wy];
+ if (wlp->flags & __ISDIRTY)
+ wlp->hash =
+ __hash((char *) wlp->line, win->maxx * __LDATASIZE);
+ }
+
+ if (win->flags & __CLEAROK || curscr->flags & __CLEAROK || curwin) {
+ if ((win->flags & __FULLWIN) || curscr->flags & __CLEAROK) {
+ tputs(CL, 0, __cputchar);
+ ly = 0;
+ lx = 0;
+ if (!curwin) {
+ curscr->flags &= ~__CLEAROK;
+ curscr->cury = 0;
+ curscr->curx = 0;
+ werase(curscr);
+ }
+ __touchwin(win);
+ }
+ win->flags &= ~__CLEAROK;
+ }
+ if (!CA) {
+ if (win->curx != 0)
+ putchar('\n');
+ if (!curwin)
+ werase(curscr);
+ }
+#ifdef DEBUG
+ __CTRACE("wrefresh: (%0.2o): curwin = %d\n", win, curwin);
+ __CTRACE("wrefresh: \tfirstch\tlastch\n");
+#endif
+
+#ifndef NOQCH
+ if ((win->flags & __FULLWIN) && !curwin) {
+ /*
+ * Invoke quickch() only if more than a quarter of the lines
+ * in the window are dirty.
+ */
+ for (wy = 0, dnum = 0; wy < win->maxy; wy++)
+ if (win->lines[wy]->flags & (__ISDIRTY | __FORCEPAINT))
+ dnum++;
+ if (!__noqch && dnum > (int) win->maxy / 4)
+ quickch(win);
+ }
+#endif
+
+#ifdef DEBUG
+{ int i, j;
+ __CTRACE("#####################################\n");
+ for (i = 0; i < curscr->maxy; i++) {
+ __CTRACE("C: %d:", i);
+ __CTRACE(" 0x%x \n", curscr->lines[i]->hash);
+ for (j = 0; j < curscr->maxx; j++)
+ __CTRACE("%c",
+ curscr->lines[i]->line[j].ch);
+ __CTRACE("\n");
+ for (j = 0; j < curscr->maxx; j++)
+ __CTRACE("%x",
+ curscr->lines[i]->line[j].attr);
+ __CTRACE("\n");
+ __CTRACE("W: %d:", i);
+ __CTRACE(" 0x%x \n", win->lines[i]->hash);
+ __CTRACE(" 0x%x ", win->lines[i]->flags);
+ for (j = 0; j < win->maxx; j++)
+ __CTRACE("%c",
+ win->lines[i]->line[j].ch);
+ __CTRACE("\n");
+ for (j = 0; j < win->maxx; j++)
+ __CTRACE("%x",
+ win->lines[i]->line[j].attr);
+ __CTRACE("\n");
+ }
+}
+#endif /* DEBUG */
+
+ for (wy = 0; wy < win->maxy; wy++) {
+#ifdef DEBUG
+ __CTRACE("%d\t%d\t%d\n",
+ wy, *win->lines[wy]->firstchp, *win->lines[wy]->lastchp);
+#endif
+ if (!curwin)
+ curscr->lines[wy]->hash = win->lines[wy]->hash;
+ if (win->lines[wy]->flags & (__ISDIRTY | __FORCEPAINT)) {
+ if (makech(win, wy) == ERR)
+ return (ERR);
+ else {
+ if (*win->lines[wy]->firstchp >= win->ch_off)
+ *win->lines[wy]->firstchp = win->maxx +
+ win->ch_off;
+ if (*win->lines[wy]->lastchp < win->maxx +
+ win->ch_off)
+ *win->lines[wy]->lastchp = win->ch_off;
+ if (*win->lines[wy]->lastchp <
+ *win->lines[wy]->firstchp) {
+#ifdef DEBUG
+ __CTRACE("wrefresh: line %d notdirty \n", wy);
+#endif
+ win->lines[wy]->flags &= ~__ISDIRTY;
+ }
+ }
+
+ }
+#ifdef DEBUG
+ __CTRACE("\t%d\t%d\n", *win->lines[wy]->firstchp,
+ *win->lines[wy]->lastchp);
+#endif
+ }
+
+#ifdef DEBUG
+ __CTRACE("refresh: ly=%d, lx=%d\n", ly, lx);
+#endif
+
+ if (win == curscr)
+ domvcur(ly, lx, win->cury, win->curx);
+ else {
+ if (win->flags & __LEAVEOK) {
+ curscr->cury = ly;
+ curscr->curx = lx;
+ ly -= win->begy;
+ lx -= win->begx;
+ if (ly >= 0 && ly < win->maxy && lx >= 0 &&
+ lx < win->maxx) {
+ win->cury = ly;
+ win->curx = lx;
+ } else
+ win->cury = win->curx = 0;
+ } else {
+ domvcur(ly, lx, win->cury + win->begy,
+ win->curx + win->begx);
+ curscr->cury = win->cury + win->begy;
+ curscr->curx = win->curx + win->begx;
+ }
+ }
+ retval = OK;
+
+ (void)fflush(stdout);
+ return (retval);
+}
+
+/*
+ * makech --
+ * Make a change on the screen.
+ */
+static int
+makech(win, wy)
+ register WINDOW *win;
+ int wy;
+{
+ static __LDATA blank = {' ', 0};
+ register int nlsp, clsp; /* Last space in lines. */
+ register int wx, lch, y;
+ register __LDATA *nsp, *csp, *cp, *cep;
+ u_int force;
+ char *ce;
+
+ /* Is the cursor still on the end of the last line? */
+ if (wy > 0 && win->lines[wy - 1]->flags & __ISPASTEOL) {
+ domvcur(ly, lx, ly + 1, 0);
+ ly++;
+ lx = 0;
+ }
+ wx = *win->lines[wy]->firstchp - win->ch_off;
+ if (wx < 0)
+ wx = 0;
+ else if (wx >= win->maxx)
+ return (OK);
+ lch = *win->lines[wy]->lastchp - win->ch_off;
+ if (lch < 0)
+ return (OK);
+ else if (lch >= (int) win->maxx)
+ lch = win->maxx - 1;
+ y = wy + win->begy;
+
+ if (curwin)
+ csp = &blank;
+ else
+ csp = &curscr->lines[wy + win->begy]->line[wx + win->begx];
+
+ nsp = &win->lines[wy]->line[wx];
+ force = win->lines[wy]->flags & __FORCEPAINT;
+ win->lines[wy]->flags &= ~__FORCEPAINT;
+ if (CE && !curwin) {
+ for (cp = &win->lines[wy]->line[win->maxx - 1];
+ cp->ch == ' ' && cp->attr == 0; cp--)
+ if (cp <= win->lines[wy]->line)
+ break;
+ nlsp = cp - win->lines[wy]->line;
+ }
+ if (!curwin)
+ ce = CE;
+ else
+ ce = NULL;
+
+ if (force) {
+ if (CM)
+ tputs(tgoto(CM, lx, ly), 0, __cputchar);
+ else {
+ tputs(HO, 0, __cputchar);
+ __mvcur(0, 0, ly, lx, 1);
+ }
+ }
+ while (wx <= lch) {
+ if (!force && memcmp(nsp, csp, sizeof(__LDATA)) == 0) {
+ if (wx <= lch) {
+ while (wx <= lch &&
+ memcmp(nsp, csp, sizeof(__LDATA)) == 0) {
+ nsp++;
+ if (!curwin)
+ csp++;
+ ++wx;
+ }
+ continue;
+ }
+ break;
+ }
+ domvcur(ly, lx, y, wx + win->begx);
+
+#ifdef DEBUG
+ __CTRACE("makech: 1: wx = %d, ly= %d, lx = %d, newy = %d, newx = %d, force =%d\n",
+ wx, ly, lx, y, wx + win->begx, force);
+#endif
+ ly = y;
+ lx = wx + win->begx;
+ while ((force || memcmp(nsp, csp, sizeof(__LDATA)) != 0)
+ && wx <= lch) {
+
+ if (ce != NULL && win->maxx + win->begx ==
+ curscr->maxx && wx >= nlsp && nsp->ch == ' ') {
+ /* Check for clear to end-of-line. */
+ cep = &curscr->lines[wy]->line[win->maxx - 1];
+ while (cep->ch == ' ' && cep->attr == 0)
+ if (cep-- <= csp)
+ break;
+ clsp = cep - curscr->lines[wy]->line -
+ win->begx * __LDATASIZE;
+#ifdef DEBUG
+ __CTRACE("makech: clsp = %d, nlsp = %d\n", clsp, nlsp);
+#endif
+ if ((clsp - nlsp >= strlen(CE)
+ && clsp < win->maxx * __LDATASIZE) ||
+ wy == win->maxy - 1) {
+#ifdef DEBUG
+ __CTRACE("makech: using CE\n");
+#endif
+ tputs(CE, 0, __cputchar);
+ lx = wx + win->begx;
+ while (wx++ <= clsp) {
+ csp->ch = ' ';
+ csp->attr = 0;
+ csp++;
+ }
+ return (OK);
+ }
+ ce = NULL;
+ }
+
+ /* Enter/exit standout mode as appropriate. */
+ if (SO && (nsp->attr & __STANDOUT) !=
+ (curscr->flags & __WSTANDOUT)) {
+ if (nsp->attr & __STANDOUT) {
+ tputs(SO, 0, __cputchar);
+ curscr->flags |= __WSTANDOUT;
+ } else {
+ tputs(SE, 0, __cputchar);
+ curscr->flags &= ~__WSTANDOUT;
+ }
+ }
+
+ wx++;
+ if (wx >= win->maxx && wy == win->maxy - 1 && !curwin)
+ if (win->flags & __SCROLLOK) {
+ if (curscr->flags & __WSTANDOUT
+ && win->flags & __ENDLINE)
+ if (!MS) {
+ tputs(SE, 0,
+ __cputchar);
+ curscr->flags &=
+ ~__WSTANDOUT;
+ }
+ if (!(win->flags & __SCROLLWIN)) {
+ if (!curwin) {
+ csp->attr = nsp->attr;
+ putchar(csp->ch = nsp->ch);
+ } else
+ putchar(nsp->ch);
+ }
+ if (wx + win->begx < curscr->maxx) {
+ domvcur(ly, wx + win->begx,
+ win->begy + win->maxy - 1,
+ win->begx + win->maxx - 1);
+ }
+ ly = win->begy + win->maxy - 1;
+ lx = win->begx + win->maxx - 1;
+ return (OK);
+ }
+ if (wx < win->maxx || wy < win->maxy - 1 ||
+ !(win->flags & __SCROLLWIN)) {
+ if (!curwin) {
+ csp->attr = nsp->attr;
+ putchar(csp->ch = nsp->ch);
+ csp++;
+ } else
+ putchar(nsp->ch);
+ }
+#ifdef DEBUG
+ __CTRACE("makech: putchar(%c)\n", nsp->ch & 0177);
+#endif
+ if (UC && (nsp->attr & __STANDOUT)) {
+ putchar('\b');
+ tputs(UC, 0, __cputchar);
+ }
+ nsp++;
+#ifdef DEBUG
+ __CTRACE("makech: 2: wx = %d, lx = %d\n", wx, lx);
+#endif
+ }
+ if (lx == wx + win->begx) /* If no change. */
+ break;
+ lx = wx + win->begx;
+ if (lx >= COLS && AM)
+ lx = COLS - 1;
+ else if (wx >= win->maxx) {
+ domvcur(ly, lx, ly, win->maxx + win->begx - 1);
+ lx = win->maxx + win->begx - 1;
+ }
+
+#ifdef DEBUG
+ __CTRACE("makech: 3: wx = %d, lx = %d\n", wx, lx);
+#endif
+ }
+ return (OK);
+}
+
+/*
+ * domvcur --
+ * Do a mvcur, leaving standout mode if necessary.
+ */
+static void
+domvcur(oy, ox, ny, nx)
+ int oy, ox, ny, nx;
+{
+ if (curscr->flags & __WSTANDOUT && !MS) {
+ tputs(SE, 0, __cputchar);
+ curscr->flags &= ~__WSTANDOUT;
+ }
+
+ __mvcur(oy, ox, ny, nx, 1);
+}
+
+/*
+ * Quickch() attempts to detect a pattern in the change of the window
+ * in order to optimize the change, e.g., scroll n lines as opposed to
+ * repainting the screen line by line.
+ */
+
+static void
+quickch(win)
+ WINDOW *win;
+{
+#define THRESH (int) win->maxy / 4
+
+ register __LINE *clp, *tmp1, *tmp2;
+ register int bsize, curs, curw, starts, startw, i, j;
+ int n, target, cur_period, bot, top, sc_region;
+ __LDATA buf[1024];
+ u_int blank_hash;
+
+ /*
+ * Find how many lines from the top of the screen are unchanged.
+ */
+ for (top = 0; top < win->maxy; top++)
+ if (win->lines[top]->flags & __FORCEPAINT ||
+ win->lines[top]->hash != curscr->lines[top]->hash
+ || memcmp(win->lines[top]->line,
+ curscr->lines[top]->line,
+ win->maxx * __LDATASIZE) != 0)
+ break;
+ else
+ win->lines[top]->flags &= ~__ISDIRTY;
+ /*
+ * Find how many lines from bottom of screen are unchanged.
+ */
+ for (bot = win->maxy - 1; bot >= 0; bot--)
+ if (win->lines[bot]->flags & __FORCEPAINT ||
+ win->lines[bot]->hash != curscr->lines[bot]->hash
+ || memcmp(win->lines[bot]->line,
+ curscr->lines[bot]->line,
+ win->maxx * __LDATASIZE) != 0)
+ break;
+ else
+ win->lines[bot]->flags &= ~__ISDIRTY;
+
+#ifdef NO_JERKINESS
+ /*
+ * If we have a bottom unchanged region return. Scrolling the
+ * bottom region up and then back down causes a screen jitter.
+ * This will increase the number of characters sent to the screen
+ * but it looks better.
+ */
+ if (bot < win->maxy - 1)
+ return;
+#endif /* NO_JERKINESS */
+
+ /*
+ * Search for the largest block of text not changed.
+ * Invariants of the loop:
+ * - Startw is the index of the beginning of the examined block in win.
+ * - Starts is the index of the beginning of the examined block in
+ * curscr.
+ * - Curs is the index of one past the end of the exmined block in win.
+ * - Curw is the index of one past the end of the exmined block in
+ * curscr.
+ * - bsize is the current size of the examined block.
+ */
+ for (bsize = bot - top; bsize >= THRESH; bsize--) {
+ for (startw = top; startw <= bot - bsize; startw++)
+ for (starts = top; starts <= bot - bsize;
+ starts++) {
+ for (curw = startw, curs = starts;
+ curs < starts + bsize; curw++, curs++)
+ if (win->lines[curw]->flags &
+ __FORCEPAINT ||
+ (win->lines[curw]->hash !=
+ curscr->lines[curs]->hash ||
+ memcmp(win->lines[curw]->line,
+ curscr->lines[curs]->line,
+ win->maxx * __LDATASIZE) != 0))
+ break;
+ if (curs == starts + bsize)
+ goto done;
+ }
+ }
+ done:
+ /* Did not find anything */
+ if (bsize < THRESH)
+ return;
+
+#ifdef DEBUG
+ __CTRACE("quickch:bsize=%d,starts=%d,startw=%d,curw=%d,curs=%d,top=%d,bot=%d\n",
+ bsize, starts, startw, curw, curs, top, bot);
+#endif
+
+ /*
+ * Make sure that there is no overlap between the bottom and top
+ * regions and the middle scrolled block.
+ */
+ if (bot < curs)
+ bot = curs - 1;
+ if (top > starts)
+ top = starts;
+
+ n = startw - starts;
+
+#ifdef DEBUG
+ __CTRACE("#####################################\n");
+ for (i = 0; i < curscr->maxy; i++) {
+ __CTRACE("C: %d:", i);
+ __CTRACE(" 0x%x \n", curscr->lines[i]->hash);
+ for (j = 0; j < curscr->maxx; j++)
+ __CTRACE("%c",
+ curscr->lines[i]->line[j].ch);
+ __CTRACE("\n");
+ for (j = 0; j < curscr->maxx; j++)
+ __CTRACE("%x",
+ curscr->lines[i]->line[j].attr);
+ __CTRACE("\n");
+ __CTRACE("W: %d:", i);
+ __CTRACE(" 0x%x \n", win->lines[i]->hash);
+ __CTRACE(" 0x%x ", win->lines[i]->flags);
+ for (j = 0; j < win->maxx; j++)
+ __CTRACE("%c",
+ win->lines[i]->line[j].ch);
+ __CTRACE("\n");
+ for (j = 0; j < win->maxx; j++)
+ __CTRACE("%x",
+ win->lines[i]->line[j].attr);
+ __CTRACE("\n");
+ }
+#endif
+
+ /* So we don't have to call __hash() each time */
+ for (i = 0; i < win->maxx; i++) {
+ buf[i].ch = ' ';
+ buf[i].attr = 0;
+ }
+ blank_hash = __hash((char *) buf, win->maxx * __LDATASIZE);
+
+ /*
+ * Perform the rotation to maintain the consistency of curscr.
+ * This is hairy since we are doing an *in place* rotation.
+ * Invariants of the loop:
+ * - I is the index of the current line.
+ * - Target is the index of the target of line i.
+ * - Tmp1 points to current line (i).
+ * - Tmp2 and points to target line (target);
+ * - Cur_period is the index of the end of the current period.
+ * (see below).
+ *
+ * There are 2 major issues here that make this rotation non-trivial:
+ * 1. Scrolling in a scrolling region bounded by the top
+ * and bottom regions determined (whose size is sc_region).
+ * 2. As a result of the use of the mod function, there may be a
+ * period introduced, i.e., 2 maps to 4, 4 to 6, n-2 to 0, and
+ * 0 to 2, which then causes all odd lines not to be rotated.
+ * To remedy this, an index of the end ( = beginning) of the
+ * current 'period' is kept, cur_period, and when it is reached,
+ * the next period is started from cur_period + 1 which is
+ * guaranteed not to have been reached since that would mean that
+ * all records would have been reached. (think about it...).
+ *
+ * Lines in the rotation can have 3 attributes which are marked on the
+ * line so that curscr is consistent with the visual screen.
+ * 1. Not dirty -- lines inside the scrolled block, top region or
+ * bottom region.
+ * 2. Blank lines -- lines in the differential of the scrolling
+ * region adjacent to top and bot regions
+ * depending on scrolling direction.
+ * 3. Dirty line -- all other lines are marked dirty.
+ */
+ sc_region = bot - top + 1;
+ i = top;
+ tmp1 = curscr->lines[top];
+ cur_period = top;
+ for (j = top; j <= bot; j++) {
+ target = (i - top + n + sc_region) % sc_region + top;
+ tmp2 = curscr->lines[target];
+ curscr->lines[target] = tmp1;
+ /* Mark block as clean and blank out scrolled lines. */
+ clp = curscr->lines[target];
+#ifdef DEBUG
+ __CTRACE("quickch: n=%d startw=%d curw=%d i = %d target=%d ",
+ n, startw, curw, i, target);
+#endif
+ if ((target >= startw && target < curw) || target < top
+ || target > bot) {
+#ifdef DEBUG
+ __CTRACE("-- notdirty");
+#endif
+ win->lines[target]->flags &= ~__ISDIRTY;
+ } else if ((n > 0 && target >= top && target < top + n) ||
+ (n < 0 && target <= bot && target > bot + n)) {
+ if (clp->hash != blank_hash || memcmp(clp->line,
+ buf, win->maxx * __LDATASIZE) !=0) {
+ (void)memcpy(clp->line, buf,
+ win->maxx * __LDATASIZE);
+#ifdef DEBUG
+ __CTRACE("-- blanked out: dirty");
+#endif
+ clp->hash = blank_hash;
+ __touchline(win, target, 0, win->maxx - 1, 0);
+ } else {
+ __touchline(win, target, 0, win->maxx - 1, 0);
+#ifdef DEBUG
+ __CTRACE(" -- blank line already: dirty");
+#endif
+ }
+ } else {
+#ifdef DEBUG
+ __CTRACE(" -- dirty");
+#endif
+ __touchline(win, target, 0, win->maxx - 1, 0);
+ }
+#ifdef DEBUG
+ __CTRACE("\n");
+#endif
+ if (target == cur_period) {
+ i = target + 1;
+ tmp1 = curscr->lines[i];
+ cur_period = i;
+ } else {
+ tmp1 = tmp2;
+ i = target;
+ }
+ }
+#ifdef DEBUG
+ __CTRACE("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$\n");
+ for (i = 0; i < curscr->maxy; i++) {
+ __CTRACE("C: %d:", i);
+ for (j = 0; j < curscr->maxx; j++)
+ __CTRACE("%c",
+ curscr->lines[i]->line[j].ch);
+ __CTRACE("\n");
+ __CTRACE("W: %d:", i);
+ for (j = 0; j < win->maxx; j++)
+ __CTRACE("%c",
+ win->lines[i]->line[j].ch);
+ __CTRACE("\n");
+ }
+#endif
+ if (n != 0) {
+ WINDOW *wp;
+ scrolln(win, starts, startw, curs, bot, top);
+ /*
+ * Need to repoint any subwindow lines to the rotated
+ * line structured.
+ */
+ for (wp = win->nextp; wp != win; wp = wp->nextp)
+ __set_subwin(win, wp);
+ }
+}
+
+/*
+ * Scrolln performs the scroll by n lines, where n is starts - startw.
+ */
+static void
+scrolln(win, starts, startw, curs, bot, top)
+ WINDOW *win;
+ int starts, startw, curs, bot, top;
+{
+ int i, oy, ox, n;
+
+ oy = curscr->cury;
+ ox = curscr->curx;
+ n = starts - startw;
+
+ if (n > 0) {
+ __mvcur(oy, ox, top, 0, 1);
+ /* Scroll up the block */
+ if (DL)
+ tputs(__tscroll(DL, n), 0, __cputchar);
+ else
+ for(i = 0; i < n; i++)
+ tputs(dl, 0, __cputchar);
+
+ /*
+ * Push down the bottom region.
+ */
+ __mvcur(top, 0, bot - n + 1, 0, 1);
+ if (AL)
+ tputs(__tscroll(AL, n), 0, __cputchar);
+ else
+ for(i = 0; i < n; i++)
+ tputs(al, 0, __cputchar);
+ __mvcur(bot - n + 1, 0, oy, ox, 1);
+ } else {
+ /* Preserve the bottom lines */
+ __mvcur(oy, ox, bot + n + 1, 0, 1); /* n < 0 */
+ if (DL)
+ tputs(__tscroll(DL, -n), 0, __cputchar);
+ else
+ for(i = n; i < 0; i++)
+ tputs(dl, 0, __cputchar);
+ __mvcur(bot + n + 1, 0, top, 0, 1);
+
+ /* Scroll the block down */
+ if (AL)
+ tputs(__tscroll(AL, -n), 0, __cputchar);
+ else
+ for(i = n; i < 0; i++)
+ tputs(al, 0, __cputchar);
+ __mvcur(top, 0, oy, ox, 1);
+ }
+}
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