[menu] Abstract out the generic concept of a jump scroller

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/src/include/ipxe/jumpscroll.h b/src/include/ipxe/jumpscroll.h
new file mode 100644
index 000000000..7a5b111c1
--- /dev/null
+++ b/src/include/ipxe/jumpscroll.h
@@ -0,0 +1,50 @@
+#ifndef _IPXE_JUMPSCROLL_H
+#define _IPXE_JUMPSCROLL_H
+
+/** @file
+ *
+ * Jump scrolling
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/** A jump scroller */
+struct jump_scroller {
+	/** Maximum number of visible rows */
+	unsigned int rows;
+	/** Total number of items */
+	unsigned int count;
+	/** Currently selected item */
+	unsigned int current;
+	/** First visible item */
+	unsigned int first;
+};
+
+/**
+ * Check if jump scroller is currently on first page
+ *
+ * @v scroll		Jump scroller
+ * @ret is_first	Scroller is currently on first page
+ */
+static inline int jump_scroll_is_first ( struct jump_scroller *scroll ) {
+
+	return ( scroll->first == 0 );
+}
+
+/**
+ * Check if jump scroller is currently on last page
+ *
+ * @v scroll		Jump scroller
+ * @ret is_last		Scroller is currently on last page
+ */
+static inline int jump_scroll_is_last ( struct jump_scroller *scroll ) {
+
+	return ( ( scroll->first + scroll->rows ) >= scroll->count );
+}
+
+extern int jump_scroll_key ( struct jump_scroller *scroll, int key );
+extern int jump_scroll_move ( struct jump_scroller *scroll, int move );
+extern int jump_scroll ( struct jump_scroller *scroll );
+
+#endif /* _IPXE_JUMPSCROLL_H */