1 files changed, 99 insertions, 0 deletions
diff --git a/src/math/mp/mp_monty.cpp b/src/math/mp/mp_monty.cpp
new file mode 100644
index 000000000..d37fb5844
--- /dev/null
+++ b/src/math/mp/mp_monty.cpp
@@ -0,0 +1,99 @@
+/*
+* Montgomery Reduction
+* (C) 1999-2011 Jack Lloyd
+*     2006 Luca Piccarreta
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/internal/mp_core.h>
+#include <botan/internal/mp_asm.h>
+#include <botan/internal/mp_asmi.h>
+#include <botan/mem_ops.h>
+
+namespace Botan {
+
+extern "C" {
+
+/*
+* Montgomery Reduction Algorithm
+*/
+void bigint_monty_redc(word z[], size_t z_size,
+                       const word p[], size_t p_size,
+                       word p_dash, word ws[])
+   {
+   const size_t blocks_of_8 = p_size - (p_size % 8);
+
+   for(size_t i = 0; i != p_size; ++i)
+      {
+      word* z_i = z + i;
+
+      const word y = z_i[0] * p_dash;
+
+      /*
+      bigint_linmul3(ws, p, p_size, y);
+      bigint_add2(z_i, z_size - i, ws, p_size+1);
+      */
+
+      word carry = 0;
+
+      for(size_t j = 0; j != blocks_of_8; j += 8)
+         carry = word8_madd3(z_i + j, p + j, y, carry);
+
+      for(size_t j = blocks_of_8; j != p_size; ++j)
+         z_i[j] = word_madd3(p[j], y, z_i[j], &carry);
+
+      word z_sum = z_i[p_size] + carry;
+      carry = (z_sum < z_i[p_size]);
+      z_i[p_size] = z_sum;
+
+      for(size_t j = p_size + 1; carry && j != z_size - i; ++j)
+         {
+         ++z_i[j];
+         carry = !z_i[j];
+         }
+      }
+
+   word borrow = 0;
+   for(size_t i = 0; i != p_size; ++i)
+      ws[i] = word_sub(z[p_size + i], p[i], &borrow);
+
+   ws[p_size] = word_sub(z[p_size+p_size], 0, &borrow);
+
+   copy_mem(ws + p_size + 1, z + p_size, p_size + 1);
+
+   copy_mem(z, ws + borrow*(p_size+1), p_size + 1);
+   clear_mem(z + p_size + 1, z_size - p_size - 1);
+   }
+
+void bigint_monty_mul(word z[], size_t z_size,
+                      const word x[], size_t x_size, size_t x_sw,
+                      const word y[], size_t y_size, size_t y_sw,
+                      const word p[], size_t p_size, word p_dash,
+                      word ws[])
+   {
+   bigint_mul(&z[0], z_size, &ws[0],
+              &x[0], x_size, x_sw,
+              &y[0], y_size, y_sw);
+
+   bigint_monty_redc(&z[0], z_size,
+                     &p[0], p_size, p_dash,
+                     &ws[0]);
+   }
+
+void bigint_monty_sqr(word z[], size_t z_size,
+                      const word x[], size_t x_size, size_t x_sw,
+                      const word p[], size_t p_size, word p_dash,
+                      word ws[])
+   {
+   bigint_sqr(&z[0], z_size, &ws[0],
+              &x[0], x_size, x_sw);
+
+   bigint_monty_redc(&z[0], z_size,
+                     &p[0], p_size, p_dash,
+                     &ws[0]);
+   }
+
+}
+
+}