OCB optimizations

From ~5 cbp to ~2.5 cbp on Skylake

3 files changed, 70 insertions, 68 deletions

diff --git a/src/lib/utils/bit_ops.h b/src/lib/utils/bit_ops.h
index a59404c75..2da0e55fb 100644
--- a/src/lib/utils/bit_ops.h
+++ b/src/lib/utils/bit_ops.h
@@ -102,6 +102,17 @@ inline size_t ctz(T n)
    return 8*sizeof(T);
    }
 
+#if defined(BOTAN_BUILD_COMPILER_IS_GCC)
+
+template<>
+inline size_t ctz(uint32_t n)
+   {
+   return __builtin_ctz(n);
+   }
+
+#endif
+
+
 template<typename T>
 size_t ceil_log2(T x)
    {
diff --git a/src/lib/utils/mem_ops.cpp b/src/lib/utils/mem_ops.cpp
index 29c93eb15..3fd463195 100644
--- a/src/lib/utils/mem_ops.cpp
+++ b/src/lib/utils/mem_ops.cpp
@@ -53,65 +53,4 @@ bool constant_time_compare(const uint8_t x[],
    return difference == 0;
    }
 
-void xor_buf(uint8_t x[],
-             const uint8_t y[],
-             size_t len)
-   {
-   while(len >= 16)
-      {
-      x[0] ^= y[0];
-      x[1] ^= y[1];
-      x[2] ^= y[2];
-      x[3] ^= y[3];
-      x[4] ^= y[4];
-      x[5] ^= y[5];
-      x[6] ^= y[6];
-      x[7] ^= y[7];
-      x[8] ^= y[8];
-      x[9] ^= y[9];
-      x[10] ^= y[10];
-      x[11] ^= y[11];
-      x[12] ^= y[12];
-      x[13] ^= y[13];
-      x[14] ^= y[14];
-      x[15] ^= y[15];
-      x += 16; y += 16; len -= 16;
-      }
-
-   for(size_t i = 0; i != len; ++i)
-      {
-      x[i] ^= y[i];
-      }
-   }
-
-void xor_buf(uint8_t out[],
-             const uint8_t in[],
-             const uint8_t in2[],
-             size_t length)
-   {
-   while(length >= 16)
-      {
-      out[0] = in[0] ^ in2[0];
-      out[1] = in[1] ^ in2[1];
-      out[2] = in[2] ^ in2[2];
-      out[3] = in[3] ^ in2[3];
-      out[4] = in[4] ^ in2[4];
-      out[5] = in[5] ^ in2[5];
-      out[6] = in[6] ^ in2[6];
-      out[7] = in[7] ^ in2[7];
-      out[8] = in[8] ^ in2[8];
-      out[9] = in[9] ^ in2[9];
-      out[10] = in[10] ^ in2[10];
-      out[11] = in[11] ^ in2[11];
-      out[12] = in[12] ^ in2[12];
-      out[13] = in[13] ^ in2[13];
-      out[14] = in[14] ^ in2[14];
-      out[15] = in[15] ^ in2[15];
-      in += 16; in2 += 16; out += 16; length -= 16;
-      }
-
-   for(size_t i = 0; i != length; ++i)
-      out[i] = in[i] ^ in2[i];
-   }
-
 }
diff --git a/src/lib/utils/mem_ops.h b/src/lib/utils/mem_ops.h
index ed4d6cb27..175f38e2f 100644
--- a/src/lib/utils/mem_ops.h
+++ b/src/lib/utils/mem_ops.h
@@ -160,9 +160,36 @@ template<typename T> inline bool same_mem(const T* p1, const T* p2, size_t n)
 * @param in the read-only input buffer
 * @param length the length of the buffers
 */
-BOTAN_PUBLIC_API(2,3) void xor_buf(uint8_t out[],
-                       const uint8_t in[],
-                       size_t length);
+inline void xor_buf(uint8_t out[],
+                    const uint8_t in[],
+                    size_t length)
+   {
+   while(length >= 16)
+      {
+      out[0] ^= in[0];
+      out[1] ^= in[1];
+      out[2] ^= in[2];
+      out[3] ^= in[3];
+      out[4] ^= in[4];
+      out[5] ^= in[5];
+      out[6] ^= in[6];
+      out[7] ^= in[7];
+      out[8] ^= in[8];
+      out[9] ^= in[9];
+      out[10] ^= in[10];
+      out[11] ^= in[11];
+      out[12] ^= in[12];
+      out[13] ^= in[13];
+      out[14] ^= in[14];
+      out[15] ^= in[15];
+      out += 16; in += 16; length -= 16;
+      }
+
+   for(size_t i = 0; i != length; ++i)
+      {
+      out[i] ^= in[i];
+      }
+   }
 
 /**
 * XOR arrays. Postcondition out[i] = in[i] ^ in2[i] forall i = 0...length
@@ -171,10 +198,35 @@ BOTAN_PUBLIC_API(2,3) void xor_buf(uint8_t out[],
 * @param in2 the second output buffer
 * @param length the length of the three buffers
 */
-BOTAN_PUBLIC_API(2,3) void xor_buf(uint8_t out[],
-                       const uint8_t in[],
-                       const uint8_t in2[],
-                       size_t length);
+inline void xor_buf(uint8_t out[],
+                    const uint8_t in[],
+                    const uint8_t in2[],
+                    size_t length)
+   {
+   while(length >= 16)
+      {
+      out[0] = in[0] ^ in2[0];
+      out[1] = in[1] ^ in2[1];
+      out[2] = in[2] ^ in2[2];
+      out[3] = in[3] ^ in2[3];
+      out[4] = in[4] ^ in2[4];
+      out[5] = in[5] ^ in2[5];
+      out[6] = in[6] ^ in2[6];
+      out[7] = in[7] ^ in2[7];
+      out[8] = in[8] ^ in2[8];
+      out[9] = in[9] ^ in2[9];
+      out[10] = in[10] ^ in2[10];
+      out[11] = in[11] ^ in2[11];
+      out[12] = in[12] ^ in2[12];
+      out[13] = in[13] ^ in2[13];
+      out[14] = in[14] ^ in2[14];
+      out[15] = in[15] ^ in2[15];
+      in += 16; in2 += 16; out += 16; length -= 16;
+      }
+
+   for(size_t i = 0; i != length; ++i)
+      out[i] = in[i] ^ in2[i];
+   }
 
 template<typename Alloc, typename Alloc2>
 void xor_buf(std::vector<uint8_t, Alloc>& out,