Initial checkin1.5.6

1 files changed, 134 insertions, 0 deletions

diff --git a/src/mp_sqr.cpp b/src/mp_sqr.cpp
new file mode 100644
index 000000000..4d1c1504a
--- /dev/null
+++ b/src/mp_sqr.cpp
@@ -0,0 +1,134 @@
+/*************************************************
+* Karatsuba Squaring Source File                 *
+* (C) 1999-2006 The Botan Project                *
+*************************************************/
+
+#include <botan/mp_core.h>
+#include <botan/mem_ops.h>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* Karatsuba Squaring Operation                   *
+*************************************************/
+void karatsuba_sqr(word z[], const word x[], u32bit N, word workspace[])
+   {
+   const u32bit KARATSUBA_SQR_LOWER_SIZE = BOTAN_KARAT_SQR_THRESHOLD;
+
+   if(N == 6)
+      bigint_comba_sqr6(z, x);
+   else if(N == 8)
+      bigint_comba_sqr8(z, x);
+   else if(N < KARATSUBA_SQR_LOWER_SIZE || N % 2)
+      bigint_simple_mul(z, x, N, x, N);
+   else
+      {
+      const u32bit N2 = N / 2;
+
+      const word* x0 = x;
+      const word* x1 = x + N2;
+      word* z0 = z;
+      word* z1 = z + N;
+
+      const s32bit cmp = bigint_cmp(x0, N2, x1, N2);
+
+      clear_mem(workspace, 2*N);
+
+      if(cmp)
+         {
+         if(cmp > 0)
+            bigint_sub3(z0, x0, N2, x1, N2);
+         else
+            bigint_sub3(z0, x1, N2, x0, N2);
+
+         karatsuba_sqr(workspace, z0, N2, workspace+N);
+         }
+
+      karatsuba_sqr(z0, x0, N2, workspace+N);
+      karatsuba_sqr(z1, x1, N2, workspace+N);
+
+      word carry = bigint_add3_nc(workspace+N, z0, N, z1, N);
+      carry += bigint_add2_nc(z + N2, N, workspace + N, N);
+      bigint_add2_nc(z + N + N2, N2, &carry, 1);
+
+      if(cmp == 0)
+         bigint_add2(z + N2, 2*N-N2, workspace, N);
+      else
+         bigint_sub2(z + N2, 2*N-N2, workspace, N);
+      }
+   }
+
+/*************************************************
+* Pick a good size for the Karatsuba squaring    *
+*************************************************/
+u32bit karatsuba_size(u32bit z_size, u32bit x_size, u32bit x_sw)
+   {
+   if(x_sw == x_size)
+      {
+      if(x_sw % 2)
+         return 0;
+      return x_sw;
+      }
+
+   for(u32bit j = x_sw; j <= x_size; ++j)
+      {
+      if(j % 2)
+         continue;
+
+      if(2*j > z_size)
+         return 0;
+
+      if(j % 4 == 2 && (j+2) <= x_size && 2*(j+2) <= z_size)
+         return j+2;
+      return j;
+      }
+
+   return 0;
+   }
+
+/*************************************************
+* Handle small operand squarings                 *
+*************************************************/
+void handle_small_sqr(word z[], u32bit z_size,
+                      const word x[], u32bit x_size, u32bit x_sw)
+   {
+   if(x_sw == 1)
+      bigint_linmul3(z, x, x_sw, x[0]);
+   else if(x_sw <= 4 && x_size >= 4 && z_size >= 8)
+      bigint_comba_sqr4(z, x);
+   else if(x_sw <= 6 && x_size >= 6 && z_size >= 12)
+      bigint_comba_sqr6(z, x);
+   else if(x_sw <= 8 && x_size >= 8 && z_size >= 16)
+      bigint_comba_sqr8(z, x);
+   else
+      bigint_simple_mul(z, x, x_sw, x, x_sw);
+   }
+
+}
+
+/*************************************************
+* Squaring Algorithm Dispatcher                  *
+*************************************************/
+void bigint_sqr(word z[], u32bit z_size, word workspace[],
+                const word x[], u32bit x_size, u32bit x_sw)
+   {
+   if(x_size <= 8 || x_size <= 8)
+      {
+      handle_small_sqr(z, z_size, x, x_size, x_sw);
+      return;
+      }
+
+   const u32bit N = karatsuba_size(z_size, x_size, x_sw);
+
+   if(N)
+      {
+      clear_mem(workspace, 2*N);
+      karatsuba_sqr(z, x, N, workspace);
+      }
+   else
+      bigint_simple_mul(z, x, x_sw, x, x_sw);
+   }
+
+}