Merge pull request #19 from bdunahu/bdunahu

cache store, handle load requests to memory, write allocate policy
-- changes look good

1 files changed, 61 insertions, 5 deletions

diff --git a/src/storage/cache.cc b/src/storage/cache.cc
index 67cedda..2031367 100644
--- a/src/storage/cache.cc
+++ b/src/storage/cache.cc
@@ -1,22 +1,78 @@
 #include "cache.h"
 #include "definitions.h"
 #include "response.h"
+#include "utils.h"
 #include <bits/stdc++.h>
 
-Cache::Cache(int lines, Storage *lower, int delay)
+Cache::Cache(Storage *lower, int delay)
 {
 	this->data = new std::vector<std::array<signed int, LINE_SIZE>>;
-	this->data->resize(lines);
-	this->lower = lower;
+	this->data->resize(L1_CACHE_SIZE);
 	this->delay = delay;
-	this->lower = nullptr;
+	this->is_waiting = false;
+	this->lower = lower;
+	this->meta.fill({-1, -1});
+	this->requester = IDLE;
+	this->wait_time = this->delay;
 }
 
 Cache::~Cache() { delete this->data; }
 
 Response Cache::write(Accessor accessor, signed int data, int address)
 {
+	Response r = WAIT;
+
+	/* Do this first--then process the first cycle immediately. */
+	if (this->requester == IDLE)
+		this->requester = accessor;
+
+	if (this->requester == accessor) {
+		fetch_resource(address);
+		if (this->is_waiting)
+			r = BLOCKED;
+		else if (this->wait_time == 0) {
+			int tag, index, offset;
+			get_bit_fields(address, &tag, &index, &offset);
+			this->data->at(index).at(offset) = data;
+			this->meta[index].at(1) = 1;
+			r = OK;
+		}
+	}
+
+	return r;
+}
+
+Response Cache::read(
+	Accessor accessor, int address, std::array<signed int, LINE_SIZE> &data)
+{
 	return WAIT;
 }
 
-Response Cache::read(Accessor accessor, int address, std::array<signed int, LINE_SIZE>& data) { return WAIT; }
+void Cache::fetch_resource(int expected)
+{
+	Response r = OK;
+	int tag, index, offset;
+	std::array<signed int, LINE_SIZE> actual;
+	std::array<int, 2> *meta;
+
+	get_bit_fields(expected, &tag, &index, &offset);
+	meta = &this->meta.at(index);
+
+	if (meta->at(0) != tag) {
+		// address not in cache
+		if (meta->at(1) >= 0) {
+			// occupant is dirty
+			// TODO
+			r = WAIT;
+		} else {
+			actual = this->data->at(index);
+			r = this->lower->read(L1CACHE, expected, actual);
+			if (r == OK) {
+				meta->at(0) = tag;
+				meta->at(1) = -1;
+			}
+		}
+	}
+
+	this->is_waiting = (r == OK) ? false : true;
+}