From 1501b3fbbdf405aae7dc996a60bd22a49c884110 Mon Sep 17 00:00:00 2001
From: Nicholas Marriott <nicm@openbsd.org>
Date: Thu, 20 Aug 2009 19:14:42 +0000
Subject: [PATCH] A few trivial optimisations: no need to check for zero size
 if calling buffer_ensure in buffer.c; expand grid lines by a greater increase
 than one each time; and don't read UTF-8 data unless it actually needs to be
 checked when overwriting a cell.

---
 buffer.c       |  5 +----
 grid.c         |  4 ++++
 screen-write.c | 26 +++++++++++++++-----------
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/buffer.c b/buffer.c
index f52d6352..5505bf74 100644
--- a/buffer.c
+++ b/buffer.c
@@ -100,9 +100,6 @@ buffer_remove(struct buffer *b, size_t size)
 void
 buffer_write(struct buffer *b, const void *data, size_t size)
 {
-	if (size == 0)
-		fatalx("zero size");
-
 	buffer_ensure(b, size);
 	memcpy(BUFFER_IN(b), data, size);
 	buffer_add(b, size);
@@ -127,7 +124,7 @@ buffer_write8(struct buffer *b, uint8_t n)
 {
 	buffer_ensure(b, 1);
 	BUFFER_IN(b)[0] = n;
-	buffer_add(b, 1);
+	b->size++;
 }
 
 /* Extract an 8-bit value. */
diff --git a/grid.c b/grid.c
index 50b3569a..31cc430b 100644
--- a/grid.c
+++ b/grid.c
@@ -198,6 +198,10 @@ grid_expand_line(struct grid *gd, u_int py, u_int sx)
 	if (sx <= gl->cellsize)
 		return;
 
+	if (gl->cellsize > gd->sx / 2)
+		sx = gd->sx;
+	else
+		sx = 1 + gl->cellsize * 2;
 	gl->celldata = xrealloc(gl->celldata, sx, sizeof *gl->celldata);
 	for (xx = gl->cellsize; xx < sx; xx++)
 		grid_put_cell(gd, xx, py, &grid_default_cell);
diff --git a/screen-write.c b/screen-write.c
index d735d450..dd553f17 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -858,7 +858,8 @@ screen_write_overwrite(struct screen_write_ctx *ctx)
 	u_int			 xx;
 
 	gc = grid_view_peek_cell(gd, s->cx, s->cy);
-	gu = grid_view_peek_utf8(gd, s->cx, s->cy);
+	if (gc->flags & GRID_FLAG_UTF8)
+		gu = grid_view_peek_utf8(gd, s->cx, s->cy);
 
 	if (gc->flags & GRID_FLAG_PADDING) {
 		/*
@@ -885,16 +886,19 @@ screen_write_overwrite(struct screen_write_ctx *ctx)
 				break;
 			grid_view_set_cell(gd, xx, s->cy, &grid_default_cell);
 		}
-	} else if (gc->flags & GRID_FLAG_UTF8 && gu->width > 1) {
-		/*
-		 * An UTF-8 wide cell; overwrite following padding cells only.
-		 */
-		xx = s->cx;
-		while (++xx < screen_size_x(s)) {
-			gc = grid_view_peek_cell(gd, xx, s->cy);
-			if (!(gc->flags & GRID_FLAG_PADDING))
-				break;
-			grid_view_set_cell(gd, xx, s->cy, &grid_default_cell);
+	} else if (gc->flags & GRID_FLAG_UTF8) {
+		gu = grid_view_peek_utf8(gd, s->cx, s->cy);
+		if (gu->width > 1) {
+			/*
+			 * An UTF-8 wide cell; overwrite following padding cells only.
+			 */
+			xx = s->cx;
+			while (++xx < screen_size_x(s)) {
+				gc = grid_view_peek_cell(gd, xx, s->cy);
+				if (!(gc->flags & GRID_FLAG_PADDING))
+					break;
+				grid_view_set_cell(gd, xx, s->cy, &grid_default_cell);
+			}
 		}
 	}
 }