From fc43e3161605eb847146163c136cbe02740aeed1 Mon Sep 17 00:00:00 2001
From: ache <ache@FreeBSD.org>
Date: Thu, 27 Oct 1994 22:36:56 +0000
Subject: [PATCH] Fix scroll bug bringed by vi(1), from phk's flame (I still
 wait for apologies)

---
 lib/libcurses/curses.c  | 2 +-
 lib/libcurses/curses.h  | 2 +-
 lib/libcurses/refresh.c | 8 ++++----
 lib/libcurses/setterm.c | 4 ++--
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/libcurses/curses.c b/lib/libcurses/curses.c
index e3081c0f575c..13ee80ee0402 100644
--- a/lib/libcurses/curses.c
+++ b/lib/libcurses/curses.c
@@ -52,7 +52,7 @@ int     __usecs = 0;                    /*
 					 * region (used only if insert/delete
 					 * line capabilities absent)
 					 */
-char	AM, BS, CA, DA, EO, HC, IN, MI, MS, NC, NS, OS, PC,
+char    AM, BS, CA, DA, DB, EO, HC, IN, MI, MS, NC, NS, OS, PC,
 	UL, XB, XN, XT, XS, XX;
 char	*AL, *BC, *BT, *CD, *CE, *CL, *CM, *CR, *CS, *DC, *DL,
 	*DM, *DO, *ED, *EI, *K0, *K1, *K2, *K3, *K4, *K5, *K6,
diff --git a/lib/libcurses/curses.h b/lib/libcurses/curses.h
index 9e1818385050..f7c7f0f0f566 100644
--- a/lib/libcurses/curses.h
+++ b/lib/libcurses/curses.h
@@ -120,7 +120,7 @@ extern int	 My_term;		/* Use Def_term regardless. */
 extern char	*Def_term;		/* Default terminal type. */
 
 /* Termcap capabilities. */
-extern char	AM, BS, CA, DA, EO, HC, IN, MI, MS, NC, NS, OS,
+extern char     AM, BS, CA, DA, DB, EO, HC, IN, MI, MS, NC, NS, OS,
 		PC, UL, XB, XN, XT, XS, XX;
 extern char	*AL, *BC, *BT, *CD, *CE, *CL, *CM, *CR, *CS, *DC, *DL,
 		*DM, *DO, *ED, *EI, *K0, *K1, *K2, *K3, *K4, *K5, *K6,
diff --git a/lib/libcurses/refresh.c b/lib/libcurses/refresh.c
index b6d432b9c31a..4cb87a3a760c 100644
--- a/lib/libcurses/refresh.c
+++ b/lib/libcurses/refresh.c
@@ -744,8 +744,8 @@ scrolln(starts, startw, curs, bot, top)
 	}
 
 	if (n > 0) {
-		/* Scroll up the block. */
-		if (SF != NULL && top == 0) {
+		/* Scroll up the screen. */
+		if ((!DB && SF != NULL || n == 1) && bot == curscr->maxy - 1 && top == 0) {
 			__mvcur(oy, ox, curscr->maxy - 1, 0, 1);
 			if (n == 1)
 				goto f_nl1;
@@ -799,8 +799,8 @@ scrolln(starts, startw, curs, bot, top)
 		 * !!!
 		 * n < 0
 		 */
-		/* Preserve the bottom lines. */
-		if (SR != NULL && bot == curscr->maxy - 1) {
+		/* Scroll down the screen. */
+		if (!DA && SR != NULL && bot == curscr->maxy - 1 && top == 0) {
 			__mvcur(oy, ox, 0, 0, 1);
 			if (sr != NULL && -n == 1)
 				goto b_sr1;
diff --git a/lib/libcurses/setterm.c b/lib/libcurses/setterm.c
index ab84e9db4965..c1da04dc99b1 100644
--- a/lib/libcurses/setterm.c
+++ b/lib/libcurses/setterm.c
@@ -50,8 +50,8 @@ extern short ospeed;
 static void zap __P((void));
 
 static char	*sflags[] = {
-		/*       am   bs   da   eo   hc   in   mi   ms  */
-			&AM, &BS, &DA, &EO, &HC, &IN, &MI, &MS,
+		/*       am   bs   da   db   eo   hc   in   mi   ms  */
+			&AM, &BS, &DA, &DB, &EO, &HC, &IN, &MI, &MS,
 		/*	 nc   ns   os   ul   xb   xn   xt   xs   xx  */
 			&NC, &NS, &OS, &UL, &XB, &XN, &XT, &XS, &XX
 		};