2 files changed, 117 insertions, 0 deletions
diff --git a/src/lib/utils/donna128.h b/src/lib/utils/donna128.h
new file mode 100644
index 000000000..f2b2d88ea
--- /dev/null
+++ b/src/lib/utils/donna128.h
@@ -0,0 +1,116 @@
+/*
+* A minimal 128-bit integer type for curve25519-donna
+* (C) 2014 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_CURVE25519_DONNA128_H__
+#define BOTAN_CURVE25519_DONNA128_H__
+
+#include <botan/mul128.h>
+
+namespace Botan {
+
+class donna128
+   {
+   public:
+      donna128(u64bit ll = 0, u64bit hh = 0) { l = ll; h = hh; }
+
+      donna128(const donna128&) = default;
+      donna128& operator=(const donna128&) = default;
+
+      friend donna128 operator>>(const donna128& x, size_t shift)
+         {
+         donna128 z = x;
+         const u64bit carry = z.h << (64 - shift);
+         z.h = (z.h >> shift);
+         z.l = (z.l >> shift) | carry;
+         return z;
+         }
+
+      friend donna128 operator<<(const donna128& x, size_t shift)
+         {
+         donna128 z = x;
+         const u64bit carry = z.l >> (64 - shift);
+         z.l = (z.l << shift);
+         z.h = (z.h << shift) | carry;
+         return z;
+         }
+
+      friend u64bit operator&(const donna128& x, u64bit mask)
+         {
+         return x.l & mask;
+         }
+
+      u64bit operator&=(u64bit mask)
+         {
+         h = 0;
+         l &= mask;
+         return l;
+         }
+
+      donna128& operator+=(const donna128& x)
+         {
+         l += x.l;
+         h += (l < x.l);
+         h += x.h;
+         return *this;
+         }
+
+      donna128& operator+=(u64bit x)
+         {
+         l += x;
+         h += (l < x);
+         return *this;
+         }
+
+      u64bit lo() const { return l; }
+      u64bit hi() const { return h; }
+   private:
+      u64bit h = 0, l = 0;
+   };
+
+inline donna128 operator*(const donna128& x, u64bit y)
+   {
+   BOTAN_ASSERT(x.hi() == 0, "High 64 bits of donna128 set to zero during multiply");
+
+   u64bit lo = 0, hi = 0;
+   mul64x64_128(x.lo(), y, &lo, &hi);
+   return donna128(lo, hi);
+   }
+
+inline donna128 operator+(const donna128& x, const donna128& y)
+   {
+   donna128 z = x;
+   z += y;
+   return z;
+   }
+
+inline donna128 operator+(const donna128& x, u64bit y)
+   {
+   donna128 z = x;
+   z += y;
+   return z;
+   }
+
+inline donna128 operator|(const donna128& x, const donna128& y)
+   {
+   return donna128(x.lo() | y.lo(), x.hi() | y.hi());
+   }
+
+inline u64bit carry_shift(const donna128& a, size_t shift)
+   {
+   return (a >> shift).lo();
+   }
+
+inline u64bit combine_lower(const donna128 a, size_t s1,
+                            const donna128 b, size_t s2)
+   {
+   donna128 z = (a >> s1) | (b << s2);
+   return z.lo();
+   }
+
+}
+
+#endif
diff --git a/src/lib/utils/info.txt b/src/lib/utils/info.txt
index 9ba51f193..84e1c8740 100644
--- a/src/lib/utils/info.txt
+++ b/src/lib/utils/info.txt
@@ -4,6 +4,7 @@ load_on always
 
 <header:internal>
 bit_ops.h
+donna128.h
 prefetch.h
 rounding.h
 semaphore.h