From 4f57e7b3d22f63e8e0e7ac8f8ce870f1943d687a Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@googlemail.com>
Date: Tue, 14 Aug 2012 17:02:56 +0200
Subject: [PATCH] console: provide scrollback-buffer helpers

These helpers allow moving around in the scrollback-buffer. Scrolling
bigger portions of the screen is quite slowly as we have to traverse a
list. However, nothing compared to screen-rendering so we can ignore this.
But O(n) is always bad...

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
---
 src/console.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/console.h |  6 ++++++
 2 files changed, 65 insertions(+)

diff --git a/src/console.c b/src/console.c
index a0fa2ef..9d7b0e7 100644
--- a/src/console.c
+++ b/src/console.c
@@ -627,6 +627,65 @@ void kmscon_console_clear_sb(struct kmscon_console *con)
 	con->sb_pos = NULL;
 }
 
+void kmscon_console_sb_up(struct kmscon_console *con, unsigned int num)
+{
+	if (!con || !num)
+		return;
+
+	while (num--) {
+		if (con->sb_pos) {
+			if (!con->sb_pos->prev)
+				return;
+
+			con->sb_pos = con->sb_pos->prev;
+		} else if (!con->sb_last) {
+			return;
+		} else {
+			con->sb_pos = con->sb_last;
+		}
+	}
+}
+
+void kmscon_console_sb_down(struct kmscon_console *con, unsigned int num)
+{
+	if (!con || !num)
+		return;
+
+	while (num--) {
+		if (con->sb_pos) {
+			con->sb_pos = con->sb_pos->next;
+			if (!con->sb_pos)
+				return;
+		} else {
+			return;
+		}
+	}
+}
+
+void kmscon_console_sb_page_up(struct kmscon_console *con, unsigned int num)
+{
+	if (!con || !num)
+		return;
+
+	kmscon_console_sb_up(con, num * con->size_y);
+}
+
+void kmscon_console_sb_page_down(struct kmscon_console *con, unsigned int num)
+{
+	if (!con || !num)
+		return;
+
+	kmscon_console_sb_down(con, num * con->size_y);
+}
+
+void kmscon_console_sb_reset(struct kmscon_console *con)
+{
+	if (!con)
+		return;
+
+	con->sb_pos = NULL;
+}
+
 void kmscon_console_set_def_attr(struct kmscon_console *con,
 				 const struct font_char_attr *attr)
 {
diff --git a/src/console.h b/src/console.h
index b7cd340..ec1bf72 100644
--- a/src/console.h
+++ b/src/console.h
@@ -63,6 +63,12 @@ int kmscon_console_set_margins(struct kmscon_console *con,
 void kmscon_console_set_max_sb(struct kmscon_console *con, unsigned int max);
 void kmscon_console_clear_sb(struct kmscon_console *con);
 
+void kmscon_console_sb_up(struct kmscon_console *con, unsigned int num);
+void kmscon_console_sb_down(struct kmscon_console *con, unsigned int num);
+void kmscon_console_sb_page_up(struct kmscon_console *con, unsigned int num);
+void kmscon_console_sb_page_down(struct kmscon_console *con, unsigned int num);
+void kmscon_console_sb_reset(struct kmscon_console *con);
+
 void kmscon_console_set_def_attr(struct kmscon_console *con,
 				 const struct font_char_attr *attr);
 void kmscon_console_reset(struct kmscon_console *con);