From 61208c9c1a674783bdeda1fc3e9149edb6fcdb54 Mon Sep 17 00:00:00 2001
From: Ali Gholami Rudi <ali@rudi.ir>
Date: Wed, 14 Aug 2013 21:33:19 +0430
Subject: [PATCH] term: more efficient management of scrolling history

---
 fbpad.h |  3 ++-
 term.c  | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/fbpad.h b/fbpad.h
index 57fd6d8..b06dc4e 100644
--- a/fbpad.h
+++ b/fbpad.h
@@ -8,7 +8,7 @@
 #define NCOLS		256		/* maximum number of screen columns */
 #define NROWS		128		/* maximum number of screen rows */
 #define NDOTS		1024		/* maximum pixels in glyphs */
-#define NHIST		32		/* scrolling history lines */
+#define NHIST		128		/* scrolling history lines */
 
 /* isdw.c */
 #define DWCHAR		0x40000000u	/* 2nd half of a fullwidth char */
@@ -33,6 +33,7 @@ struct term {
 	char fgs[NROWS * NCOLS];
 	char bgs[NROWS * NCOLS];
 	struct term_state cur, sav;
+	int histtail;			/* the next history row */
 	int fd;
 	int pid;
 	int top, bot;
diff --git a/term.c b/term.c
index b266c10..7d9f105 100644
--- a/term.c
+++ b/term.c
@@ -431,13 +431,16 @@ static void blank_rows(int sr, int er)
 	draw_cursor(1);
 }
 
+#define HISTROW(pos)	(term->hist + ((term->histtail + NHIST - (pos)) % NHIST) * pad_cols())
+
 static void scrl_rows(int nr)
 {
-	int nc = nr * pad_cols();
-	memmove(term->hist, term->hist + nc,
-			(LEN(term->hist) - nc) * sizeof(term->hist[0]));
-	memcpy(term->hist + LEN(term->hist) - nc, term->screen,
-			nc * sizeof(term->hist[0]));
+	int i;
+	for (i = 0; i < nr; i++) {
+		memcpy(HISTROW(0), screen + i * pad_cols(),
+				pad_cols() * sizeof(screen[0]));
+		term->histtail = (term->histtail + 1) % NHIST;
+	}
 }
 
 void term_hist(int scrl)
@@ -448,12 +451,12 @@ void term_hist(int scrl)
 	lazy_start();
 	memset(dirty, 1, sizeof(dirty));
 	for (i = 0; i < pad_rows(); i++) {
-		int off = (i - scrl) * pad_cols();
 		if (i < scrl) {
-			_scr = term->hist + LEN(term->hist) + off;
+			_scr = HISTROW(scrl - i);
 			_fgs = NULL;
 			_bgs = NULL;
 		} else {
+			int off = (i - scrl) * pad_cols();
 			_scr = term->screen + off;
 			_fgs = term->fgs + off;
 			_bgs = term->bgs + off;
-- 
2.11.4.GIT