From a298ad9ba29a71edd23ed0129c6fe0c0a3f02159 Mon Sep 17 00:00:00 2001
From: Pavel Kirienko <pavel.kirienko@gmail.com>
Date: Wed, 16 Apr 2014 17:19:05 +0400
Subject: [PATCH] Transport CRC will not use table in UAVCAN_TINY builds

---
 libuavcan/include/uavcan/transport/crc.hpp | 21 +++++++++++++++++++++
 libuavcan/src/transport/uc_crc.cpp         |  5 ++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/libuavcan/include/uavcan/transport/crc.hpp b/libuavcan/include/uavcan/transport/crc.hpp
index 91c6be0423..c025ec13f3 100644
--- a/libuavcan/include/uavcan/transport/crc.hpp
+++ b/libuavcan/include/uavcan/transport/crc.hpp
@@ -26,7 +26,10 @@ namespace uavcan
  */
 class UAVCAN_EXPORT TransferCRC
 {
+#if !UAVCAN_TINY
     static const uint16_t Table[256];
+#endif
+
     uint16_t value_;
 
 public:
@@ -36,10 +39,28 @@ public:
         : value_(0xFFFF)
     { }
 
+#if UAVCAN_TINY
+    void add(uint8_t byte)
+    {
+        value_ ^= byte << 8;
+        for (uint8_t bit = 8; bit > 0; --bit)
+        {
+            if (value_ & 0x8000)
+            {
+                value_ = (value_ << 1) ^ 0x1021;
+            }
+            else
+            {
+                value_ = (value_ << 1);
+            }
+        }
+    }
+#else
     void add(uint8_t byte)
     {
         value_ = ((value_ << 8) ^ Table[((value_ >> 8) ^ byte) & 0xFF]) & 0xFFFF;
     }
+#endif
 
     void add(const uint8_t* bytes, unsigned len)
     {
diff --git a/libuavcan/src/transport/uc_crc.cpp b/libuavcan/src/transport/uc_crc.cpp
index 39856e116e..0ef8f7ef80 100644
--- a/libuavcan/src/transport/uc_crc.cpp
+++ b/libuavcan/src/transport/uc_crc.cpp
@@ -2,12 +2,13 @@
  * Copyright (C) 2014 Pavel Kirienko <pavel.kirienko@gmail.com>
  */
 
-#include <cassert>
 #include <uavcan/transport/crc.hpp>
 
 namespace uavcan
 {
 
+#if !UAVCAN_TINY
+
 // print ', '.join(map(lambda x: '%04x' % x, map(lambda x: int(x, 0), c.crc_ccitt_tab)))
 const uint16_t TransferCRC::Table[256] =
 {
@@ -45,4 +46,6 @@ const uint16_t TransferCRC::Table[256] =
     0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
 };
 
+#endif
+
 }