From ec29b81418af4a41e87925e0eb549cf273e234dd Mon Sep 17 00:00:00 2001
From: Jacob <jikomissar@wpi.edu>
Date: Fri, 29 Apr 2016 17:57:02 -0400
Subject: [PATCH] Slightly reorganized cache_access. Moved set re-linking to
 new function update_set.

---
 csim.c | 42 +++++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 15 deletions(-)

diff --git a/csim.c b/csim.c
index 0662f18..5cbffdf 100644
--- a/csim.c
+++ b/csim.c
@@ -73,6 +73,7 @@ void print_set(linked_line* line);
 /* Cache access functions */
 char cache_access(linked_line** cache, long address, int set_bits, int block_offset_bits, long num_lines);
 linked_line* find_line(linked_line* set_head, long tag);
+linked_line* update_set(linked_line* old_head, linked_line* new_head);
 //linked_line* move_to_head(linked_line* new_head, linked_line* old_head);
 
 
@@ -403,30 +404,21 @@ char cache_access(linked_line** cache, long address,
 	linked_line* line = find_line(set_head, tag);
 
 	if (!line->validity) {
-		out = 'M';
+		operation = 'M';
 	}
 	else if (line->tag == tag) {
-		out = 'H';
+		operation = 'H';
 	}
 	else {
-		out = 'E';
-	}
-
-	if(!(line == set_head)) {
-		line->newer->older = line->older;
-		if(line->older) {
-			line->older->newer = line->newer;
-		}
-		line->newer = NULL;
-		line->older = set_head;
-		set_head->newer = line;
-		cache[set] = line;
+		operation = 'E';
 	}
 
 	line->tag = tag;
 	line->validity = 1;
 
-	return out;
+	cache[set] = update_set(set_head, line);
+
+	return operation;
 }
 
 /**
@@ -448,4 +440,24 @@ linked_line* find_line(linked_line* line, long tag)
 	}
 }
 
+/**
+   Updates the use order of a set by moving the line being accessed in front of
+   the previously-accessed line and linking the neighbors of the new head.
+   @param old_head The previous most-recently modified line of the set.
+   @param new_head The line of the set being accessed.
+   @return new_head
+ */
+linked_line* update_set(linked_line* old_head, linked_line* new_head) {
+	if(!(new_head == old_head)) {
+		new_head->newer->older = new_head->older;
+		if(new_head->older) {
+			new_head->older->newer = new_head->newer;
+		}
+		new_head->newer = NULL;
+		new_head->older = old_head;
+		old_head->newer = new_head;
+	}
+	return new_head;
+}
+