1 files changed, 58 insertions, 6 deletions
diff --git a/include/bit_ops.h b/include/bit_ops.h
index 41c401028..42b922620 100644
--- a/include/bit_ops.h
+++ b/include/bit_ops.h
@@ -11,13 +11,65 @@
 namespace Botan {
 
 /*************************************************
-* Simple Bit Manipulation                        *
+* Return true iff arg is 2**n for some n > 0     *
+* T should be an unsigned integer type           *
+* 
 *************************************************/
-bool power_of_2(u64bit);
-u32bit high_bit(u64bit);
-u32bit low_bit(u64bit);
-u32bit significant_bytes(u64bit);
-u32bit hamming_weight(u64bit);
+template<typename T>
+inline bool power_of_2(T arg)
+   {
+   return ((arg != 0 && arg != 1) && ((arg & (arg-1)) == 0));
+   }
+
+/*************************************************
+* Return the index of the highest set bit
+* T is an unsigned integer type
+*************************************************/
+template<typename T>
+inline u32bit high_bit(T n)
+   {
+   for(u32bit i = 8*sizeof(T); i > 0; --i)
+      if((n >> (i - 1)) & 0x01)
+         return i;
+   return 0;
+   }
+
+/*************************************************
+* Return the index of the lowest set bit         *
+*************************************************/
+template<typename T>
+inline u32bit low_bit(T n)
+   {
+   for(u32bit i = 0; i != 8*sizeof(T); ++i)
+      if((n >> i) & 0x01)
+         return (i + 1);
+   return 0;
+   }
+
+/*************************************************
+* Return the number of significant bytes in n    *
+*************************************************/
+template<typename T>
+inline u32bit significant_bytes(T n)
+   {
+   for(u32bit j = 0; j != sizeof(T); ++j)
+      if(get_byte(j, n))
+         return sizeof(T)-j;
+   return 0;
+   }
+
+/*************************************************
+* Return the Hamming weight of n                 *
+*************************************************/
+template<typename T>
+inline u32bit hamming_weight(T n)
+   {
+   u32bit weight = 0;
+   for(u32bit j = 0; j != 8*sizeof(T); ++j)
+      if((n >> j) & 0x01)
+         ++weight;
+   return weight;
+   }
 
 }