3 files changed, 69 insertions, 3 deletions
diff --git a/inc/cache.h b/inc/cache.h
index d470e6c..d9d8ba7 100644
--- a/inc/cache.h
+++ b/inc/cache.h
@@ -1,6 +1,9 @@
 #ifndef CACHE_H
 #define CACHE_H
-#include <storage.h>
+#include "definitions.h"
+#include "storage.h"
+#include <array>
+#include <bitset>
 
 class Cache : public Storage
 {
@@ -19,6 +22,15 @@ class Cache : public Storage
 
 	Response write(Accessor accessor, signed int data, int address) override;
 	Response read(Accessor accessor, int address, std::array<signed int, LINE_SIZE>& data) override;
+
+  private:
+	/**
+	 * An array of paired bits.
+	 * If the least significant bit of an element is set, the corresponding
+	 * element in `data` is invalid. If the most significant bit of an element
+	 * is set, the corresponding element in `data` is dirty.
+	 */
+	std::array<std::bitset<2>, L1_CACHE_SIZE> stat;
 };
 
 #endif /* CACHE_H_INCLUDED */
diff --git a/inc/definitions.h b/inc/definitions.h
index 1593162..877065e 100644
--- a/inc/definitions.h
+++ b/inc/definitions.h
@@ -1,10 +1,50 @@
 #ifndef DEFINITIONS_H
 #define DEFINITIONS_H
+#include <cmath>
 
 /**
- * Defines common macros.
+ * The number of bits to specify a word in a line
  */
+#define LINE_SPEC 2
+/**
+ * The total number of words in a line
+ */
+#define LINE_SIZE (int)pow(2, 2)
+
+/**
+ * The number of bits to specify a memory line
+ * calculated as: (/ (expt 2 15) 4)
+ */
+#define MEM_SPEC 13
+/**
+ * The total number of words in memory
+ */
+#define MEM_SIZE (int)pow(2, MEM_SPEC)
+
+/**
+ * The number of bits to specify a l1 cache line
+ */
+#define L1_CACHE_SPEC 5
+/**
+ * The total number of words in l1 cache
+ */
+#define L1_CACHE_SIZE (int)pow(2, L1_CACHE_SPEC)
 
-#define LINE_SIZE 4
+/**
+ * Return the N least-significant bits from integer K using a bit mask
+ * @param the integer to be parsed
+ * @param the number of bits to be parsed
+ * @return the N least-significant bits from K
+ */
+#define GET_LS_BITS(k, n) ((k) & ((1 << (n)) - 1))
+/**
+ * Return the bits from integer K starting at N and ending at M using a bit
+ * mask
+ * @param the integer to be parsed
+ * @param the index of the starting bit to be parsed
+ * @param the index of the ending bit to be parsed
+ * @return a section of bits from K
+ */
+#define GET_MID_BITS(k, m, n) GET_LS_BITS((k) >> (m), ((n) - (m)))
 
 #endif /* DEFINITIONS_H_INCLUDED */
diff --git a/inc/utils.h b/inc/utils.h
new file mode 100644
index 0000000..e258ed8
--- /dev/null
+++ b/inc/utils.h
@@ -0,0 +1,14 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+/**
+ * Parse an address into a tag, index into the cache table, and a line
+ * offset.
+ * @param the address to be parsed
+ * @param the resulting tag
+ * @param the resulting index
+ * @param the resulting offset
+ */
+void get_bit_fields(int address, int *tag, int *index, int *offset);
+
+#endif /* UTILS_H_INCLUDED */