1 files changed, 44 insertions, 0 deletions
diff --git a/src/utility.h b/src/utility.h
index 50f27c11b..f4c7c3017 100644
--- a/src/utility.h
+++ b/src/utility.h
@@ -1757,6 +1757,50 @@ protected:
 	float m_accumulator;
 };
 
+/*
+	Splits a list into "pages". For example, the list [1,2,3,4,5] split
+	into two pages would be [1,2,3],[4,5]. This function computes the
+	minimum and maximum indices of a single page.
+
+	length: Length of the list that should be split
+	page: Page number, 1 <= page <= pagecount
+	pagecount: The number of pages, >= 1
+	minindex: Receives the minimum index (inclusive).
+	maxindex: Receives the maximum index (exclusive).
+
+	Ensures 0 <= minindex <= maxindex <= length.
+*/
+inline void paging(u32 length, u32 page, u32 pagecount, u32 &minindex, u32 &maxindex)
+{
+	if(length < 1 || pagecount < 1 || page < 1 || page > pagecount)
+	{
+		// Special cases or invalid parameters
+		minindex = maxindex = 0;
+	}
+	else if(pagecount <= length)
+	{
+		// Less pages than entries in the list:
+		// Each page contains at least one entry
+		minindex = (length * (page-1) + (pagecount-1)) / pagecount;
+		maxindex = (length * page + (pagecount-1)) / pagecount;
+	}
+	else
+	{
+		// More pages than entries in the list:
+		// Make sure the empty pages are at the end
+		if(page < length)
+		{
+			minindex = page-1;
+			maxindex = page;
+		}
+		else
+		{
+			minindex = 0;
+			maxindex = 0;
+		}
+	}
+}
+
 std::string translatePassword(std::string playername, std::wstring password);
 
 enum PointedThingType