diff --git a/a8/fifobuffer.cc b/a8/fifobuffer.cc
index 03af6f0..79351d8 100644
--- a/a8/fifobuffer.cc
+++ b/a8/fifobuffer.cc
@@ -1,10 +1,15 @@
+#include <cmath>
+
 #include <a8/a8.h>
 
 #include <a8/fifobuffer.h>
+#include <a8/list.h>
+
+const int BASE_BLOCK_SIZE = 128;
 
 struct BufHead
 {
-    int len = 0;
+    list_head entry;
 };
 
 namespace a8
@@ -17,8 +22,8 @@ namespace a8
         }
         buf_ = (char*)malloc(buf_len);
         buf_len_ = buf_len;
-        for (size_t i = 0; i < chunk_pool_.size(); ++i) {
-            INIT_LIST_HEAD(&chunk_pool_[i]);
+        for (size_t i = 0; i < free_list_.size(); ++i) {
+            INIT_LIST_HEAD(&free_list_[i]);
         }
     }
 
@@ -31,10 +36,46 @@ namespace a8
 
     char* FifoBuffer::Alloc(int len)
     {
+        if (len <= 0) {
+            abort();
+        }
+        int real_len = sizeof(BufHead) + len;
+        if (real_len > 1024 * 64) {
+            return (char*)malloc(len);
+        } else {
+            size_t index = GetIndex(real_len);
+        }
     }
 
     void FifoBuffer::Free(char* p)
     {
     }
 
+    size_t FifoBuffer::GetIndex(size_t size)
+    {
+        if (size <= 128 * std::pow(2, 0)) {
+            return 0;
+        } else if (size <= 128 * std::pow(2, 1)) {
+            return 1;
+        } else if (size <= 128 * std::pow(2, 2)) {
+            return 2;
+        } else if (size <= 128 * std::pow(2, 3)) {
+            return 3;
+        } else if (size <= 128 * std::pow(2, 4)) {
+            return 4;
+        } else if (size <= 128 * std::pow(2, 5)) {
+            return 5;
+        } else if (size <= 128 * std::pow(2, 6)) {
+            return 6;
+        } else if (size <= 128 * std::pow(2, 7)) {
+            return 7;
+        } else if (size <= 128 * std::pow(2, 8)) {
+            return 8;
+        } else if (size <= 128 * std::pow(2, 9)) {
+            return 9;
+        } else {
+            abort();
+        }
+    }
+
 }
diff --git a/a8/fifobuffer.h b/a8/fifobuffer.h
index d34b899..e9b4ec9 100644
--- a/a8/fifobuffer.h
+++ b/a8/fifobuffer.h
@@ -15,13 +15,17 @@ namespace a8
         char* Alloc(int len);
         void Free(char* p);
 
+    private:
+
+        size_t GetIndex(size_t size);
+
     private:
 
         char* buf_ = nullptr;
         int buf_len_ = 0;
 
         a8::SpinLock lock_;
-        std::array<list_head, 10> chunk_pool_;
+        std::array<list_head, 10> free_list_;
     };
 
 }