From 55f7d54ea98fcec0eb7e224e5d54e63c2a28de49 Mon Sep 17 00:00:00 2001
From: polymurph <eddyed.k@gmail.com>
Date: Mon, 23 Aug 2021 08:51:58 +0200
Subject: [PATCH] added BitField to utils

---
 utils/BitFiled.hpp | 76 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 utils/BitFiled.hpp

diff --git a/utils/BitFiled.hpp b/utils/BitFiled.hpp
new file mode 100644
index 0000000..c3f4a3a
--- /dev/null
+++ b/utils/BitFiled.hpp
@@ -0,0 +1,76 @@
+/**
+ * @file BitField.h
+ * @author Edwin Koch (eddyed.k@gmail.com)
+ * @brief 
+ * @version 0.1
+ * @date 2020-12-19
+ * 
+ * @copyright Copyright (c) 2020
+ * 
+ */
+
+// Based on:
+// https://www.youtube.com/watch?v=TYqbgvHfxjM
+// https://stackoverflow.com/questions/31726191/is-there-a-portable-alternative-to-c-bitfields
+// https://stackoverflow.com/questions/1392059/algorithm-to-generate-bit-mask
+#ifndef _BITFIELDS_HPP_
+#define _BITFIELDS_HPP_
+#include <stdint.h>
+/**
+ * @brief Template class for portable Bitfields
+ * 
+ * @tparam T type of variable in which the bitfield resides
+ * @tparam START bit index starting from LSB where the bitfield starts
+ * @tparam SIZE number of bits
+ */
+template<typename T, uint8_t START, uint8_t SIZE>
+struct BitField
+{   
+    /**
+     * @brief Construct a new Bit Field object
+     * 
+     */
+    BitField()
+    {
+        static_assert(SIZE != 0, "Bitfield SIZE must be > 0!");
+		static_assert(START < sizeof(T) * 8, "START exceeds number of bits of the chosen typename T!");
+    }
+    
+    /**
+     * @brief assignment operator
+     * 
+     * @param v value to be written in the bitfield
+     * @return BitField&
+     */
+    BitField& operator =(T v)
+    {
+        // use bit band alias if system permits
+        _raw = ((v & ((1ULL << SIZE)-1)) << START) | (_raw & ~(((1ULL << SIZE)-1) << START));
+        return *this;
+    }
+    
+    /**
+     * @brief return the value inside the bitfield
+     * 
+     * @return T 
+     */
+    operator T() const
+    {
+        return (_raw >> START) & ((1ULL << SIZE) - 1);
+    }
+    
+    /**
+     * @brief return the raw value
+     * 
+     * @return T 
+     */
+    T operator ()() const
+    {
+        return (_raw >> START) & ((1ULL << SIZE) - 1);
+    }
+    
+    private:
+    T _raw;
+};
+
+#endif // _BITFIELDS_HPP_