From cb64e374dd6767732de6530904ad8452f447ac6f Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Mon, 8 Aug 2016 21:01:40 +0200
Subject: [PATCH] New features of the block cache

---
 kernel/include/block_cache.hpp |  3 +++
 kernel/src/block_cache.cpp     | 45 ++++++++++++++++++++++------------
 2 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/kernel/include/block_cache.hpp b/kernel/include/block_cache.hpp
index cc4aaedb..2f19ba72 100644
--- a/kernel/include/block_cache.hpp
+++ b/kernel/include/block_cache.hpp
@@ -22,6 +22,9 @@ struct block_cache {
 
     void init(uint64_t payload_size, uint64_t blocks);
 
+    char* block_if_present(uint16_t device, uint64_t sector);
+    char* block_if_present(uint64_t key);
+
     char* block(uint16_t device, uint64_t sector, bool& valid);
     char* block(uint64_t key, bool& valid);
 };
diff --git a/kernel/src/block_cache.cpp b/kernel/src/block_cache.cpp
index b5cbe376..c6951c79 100644
--- a/kernel/src/block_cache.cpp
+++ b/kernel/src/block_cache.cpp
@@ -48,6 +48,32 @@ void block_cache::init(uint64_t payload_size, uint64_t blocks){
     rear = previous;
 }
 
+char* block_cache::block_if_present(uint16_t device, uint64_t sector){
+    return block_if_present((uint64_t(device) << 16) + sector);
+}
+
+char* block_cache::block_if_present(uint64_t orig_key){
+    auto key = orig_key % (blocks * 2);
+
+    if(hash_table[key]){
+        auto* entry = static_cast<uint64_t*>(hash_table[key]);
+
+        if(entry[0] == orig_key){
+            return reinterpret_cast<char*>(reinterpret_cast<size_t>(hash_table[key]) + 4 * sizeof(uint64_t));
+        } else {
+            while(entry[1]){
+               entry = reinterpret_cast<uint64_t*>(entry[1]);
+
+               if(entry[0] == orig_key){
+                   return reinterpret_cast<char*>(reinterpret_cast<size_t>(entry) + 4 * sizeof(uint64_t));
+               }
+            }
+        }
+    }
+
+    return nullptr;
+}
+
 char* block_cache::block(uint16_t device, uint64_t sector, bool& valid){
     return block((uint64_t(device) << 16) + sector, valid);
 }
@@ -57,22 +83,11 @@ char* block_cache::block(uint64_t orig_key, bool& valid){
 
     // First, try to get it directly from the hash table
 
-    if(hash_table[key]){
-        auto* entry = static_cast<uint64_t*>(hash_table[key]);
+    auto direct = block_if_present(orig_key);
 
-        if(entry[0] == orig_key){
-            valid = true;
-            return reinterpret_cast<char*>(reinterpret_cast<size_t>(hash_table[key]) + 4 * sizeof(uint64_t));
-        } else {
-            while(entry[1]){
-               entry = reinterpret_cast<uint64_t*>(entry[1]);
-
-               if(entry[0] == orig_key){
-                   valid = true;
-                   return reinterpret_cast<char*>(reinterpret_cast<size_t>(entry) + 4 * sizeof(uint64_t));
-               }
-            }
-        }
+    if(direct){
+        valid = true;
+        return direct;
     }
 
     // At this point, we will allocate a new block