1 files changed, 91 insertions, 0 deletions
diff --git a/botan/build/botan/bit_ops.h b/botan/build/botan/bit_ops.h
new file mode 100644
index 0000000..c02ec53
--- /dev/null
+++ b/botan/build/botan/bit_ops.h
@@ -0,0 +1,91 @@
+/*
+* Bit/Word Operations
+* (C) 1999-2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_BIT_OPS_H__
+#define BOTAN_BIT_OPS_H__
+
+#include <botan/types.h>
+
+namespace Botan {
+
+/*
+* Return true iff arg is 2**n for some n > 0
+* T should be an unsigned integer type
+*/
+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)
+   {
+   const byte NIBBLE_WEIGHTS[] = {
+      0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4 };
+
+   u32bit weight = 0;
+   for(u32bit i = 0; i != 2*sizeof(T); ++i)
+      weight += NIBBLE_WEIGHTS[(n >> (4*i)) & 0x0F];
+   return weight;
+   }
+
+/*
+* Count the trailing zero bits in n
+*/
+template<typename T>
+inline u32bit ctz(T n)
+   {
+   for(u32bit i = 0; i != 8*sizeof(T); ++i)
+      if((n >> i) & 0x01)
+         return i;
+   return 8*sizeof(T);
+   }
+
+}
+
+#endif