From e3b9c0140a8804bff247ba6541b6d39dab91e147 Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Wed, 6 Jan 2021 23:20:29 -0800
Subject: [PATCH] [fb] Simplify scrollback line counting

Using a start and a count was redundant when we know how many lines are
in the buffer already.
---
 src/drivers/fb/scrollback.cpp | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/drivers/fb/scrollback.cpp b/src/drivers/fb/scrollback.cpp
index 170dd09..69aa017 100644
--- a/src/drivers/fb/scrollback.cpp
+++ b/src/drivers/fb/scrollback.cpp
@@ -8,7 +8,6 @@
 scrollback::scrollback(unsigned lines, unsigned cols, unsigned margin) :
 	m_rows {lines},
 	m_cols {cols},
-	m_start {0},
 	m_count {0},
 	m_margin {margin}
 {
@@ -23,24 +22,20 @@ scrollback::scrollback(unsigned lines, unsigned cols, unsigned margin) :
 void
 scrollback::add_line(const char *line, size_t len)
 {
-	unsigned i = 0;
-	if (m_count < m_rows)
-		i = m_count++;
-	else
-		i = m_start++;
+	unsigned i = m_count++ % m_rows;
 
 	if (len > m_cols)
 		len = m_cols;
 
-	memcpy(m_lines[i % m_rows], line, len);
+	memcpy(m_lines[i], line, len);
 	if (len < m_cols)
-		memset(m_lines[i % m_rows]+len, ' ', m_cols - len);
+		memset(m_lines[i]+len, ' ', m_cols - len);
 }
 
 char *
 scrollback::get_line(unsigned i)
 {
-	return m_lines[(i+m_start)%m_rows];
+	return m_lines[(i+m_count)%m_rows];
 }
 
 void