1 files changed, 138 insertions, 0 deletions
diff --git a/lib/math/mp/mp_shift.cpp b/lib/math/mp/mp_shift.cpp
new file mode 100644
index 000000000..0531658ec
--- /dev/null
+++ b/lib/math/mp/mp_shift.cpp
@@ -0,0 +1,138 @@
+/*
+* MP Shift Algorithms
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/internal/mp_core.h>
+#include <botan/mem_ops.h>
+
+namespace Botan {
+
+extern "C" {
+
+/*
+* Single Operand Left Shift
+*/
+void bigint_shl1(word x[], size_t x_size, size_t word_shift, size_t bit_shift)
+   {
+   if(word_shift)
+      {
+      for(size_t j = 1; j != x_size + 1; ++j)
+         x[(x_size - j) + word_shift] = x[x_size - j];
+      clear_mem(x, word_shift);
+      }
+
+   if(bit_shift)
+      {
+      word carry = 0;
+      for(size_t j = word_shift; j != x_size + word_shift + 1; ++j)
+         {
+         word temp = x[j];
+         x[j] = (temp << bit_shift) | carry;
+         carry = (temp >> (MP_WORD_BITS - bit_shift));
+         }
+      }
+   }
+
+/*
+* Single Operand Right Shift
+*/
+void bigint_shr1(word x[], size_t x_size, size_t word_shift, size_t bit_shift)
+   {
+   if(x_size < word_shift)
+      {
+      clear_mem(x, x_size);
+      return;
+      }
+
+   if(word_shift)
+      {
+      copy_mem(x, x + word_shift, x_size - word_shift);
+      clear_mem(x + x_size - word_shift, word_shift);
+      }
+
+   if(bit_shift)
+      {
+      word carry = 0;
+
+      size_t top = x_size - word_shift;
+
+      while(top >= 4)
+         {
+         word w = x[top-1];
+         x[top-1] = (w >> bit_shift) | carry;
+         carry = (w << (MP_WORD_BITS - bit_shift));
+
+         w = x[top-2];
+         x[top-2] = (w >> bit_shift) | carry;
+         carry = (w << (MP_WORD_BITS - bit_shift));
+
+         w = x[top-3];
+         x[top-3] = (w >> bit_shift) | carry;
+         carry = (w << (MP_WORD_BITS - bit_shift));
+
+         w = x[top-4];
+         x[top-4] = (w >> bit_shift) | carry;
+         carry = (w << (MP_WORD_BITS - bit_shift));
+
+         top -= 4;
+         }
+
+      while(top)
+         {
+         word w = x[top-1];
+         x[top-1] = (w >> bit_shift) | carry;
+         carry = (w << (MP_WORD_BITS - bit_shift));
+
+         top--;
+         }
+      }
+   }
+
+/*
+* Two Operand Left Shift
+*/
+void bigint_shl2(word y[], const word x[], size_t x_size,
+                 size_t word_shift, size_t bit_shift)
+   {
+   for(size_t j = 0; j != x_size; ++j)
+      y[j + word_shift] = x[j];
+   if(bit_shift)
+      {
+      word carry = 0;
+      for(size_t j = word_shift; j != x_size + word_shift + 1; ++j)
+         {
+         word w = y[j];
+         y[j] = (w << bit_shift) | carry;
+         carry = (w >> (MP_WORD_BITS - bit_shift));
+         }
+      }
+   }
+
+/*
+* Two Operand Right Shift
+*/
+void bigint_shr2(word y[], const word x[], size_t x_size,
+                 size_t word_shift, size_t bit_shift)
+   {
+   if(x_size < word_shift) return;
+
+   for(size_t j = 0; j != x_size - word_shift; ++j)
+      y[j] = x[j + word_shift];
+   if(bit_shift)
+      {
+      word carry = 0;
+      for(size_t j = x_size - word_shift; j > 0; --j)
+         {
+         word w = y[j-1];
+         y[j-1] = (w >> bit_shift) | carry;
+         carry = (w << (MP_WORD_BITS - bit_shift));
+         }
+      }
+   }
+
+}
+
+}