1 files changed, 117 insertions, 0 deletions
diff --git a/src/mp_misc.cpp b/src/mp_misc.cpp
new file mode 100644
index 000000000..4b5cf1fc9
--- /dev/null
+++ b/src/mp_misc.cpp
@@ -0,0 +1,117 @@
+/*************************************************
+* MP Misc Functions Source File                  *
+* (C) 1999-2006 The Botan Project                *
+*************************************************/
+
+#include <botan/mp_core.h>
+#include <botan/mp_asm.h>
+
+namespace Botan {
+
+extern "C" {
+
+/*************************************************
+* Core Division Operation                        *
+*************************************************/
+u32bit bigint_divcore(word q, word y1, word y2,
+                      word x1, word x2, word x3)
+   {
+   word y0 = 0;
+   y2 = word_madd2(q, y2, 0, &y0);
+   y1 = word_madd2(q, y1, y0, &y0);
+
+   if(y0 > x1) return 1;
+   if(y0 < x1) return 0;
+   if(y1 > x2)  return 1;
+   if(y1 < x2)  return 0;
+   if(y2 > x3)  return 1;
+   if(y2 < x3)  return 0;
+   return 0;
+   }
+
+/*************************************************
+* Compare two MP integers                        *
+*************************************************/
+s32bit bigint_cmp(const word x[], u32bit x_size,
+                  const word y[], u32bit y_size)
+   {
+   if(x_size < y_size) { return (-bigint_cmp(y, y_size, x, x_size)); }
+
+   while(x_size > y_size)
+      {
+      if(x[x_size-1])
+         return 1;
+      x_size--;
+      }
+   for(u32bit j = x_size; j > 0; --j)
+      {
+      if(x[j-1] > y[j-1]) return 1;
+      if(x[j-1] < y[j-1]) return -1;
+      }
+   return 0;
+   }
+
+/*************************************************
+* Do a 2-word/1-word Division                    *
+*************************************************/
+word bigint_divop(word n1, word n0, word d)
+   {
+   word high = n1 % d;
+   word quotient = 0;
+   for(u32bit j = 0; j != MP_WORD_BITS; ++j)
+      {
+      const word mask = (word)1 << (MP_WORD_BITS-1-j);
+      const bool high_top_bit = (high & MP_WORD_TOP_BIT) ? true : false;
+
+      high = (high << 1) | ((n0 & mask) >> (MP_WORD_BITS-1-j));
+
+      if(high_top_bit || high >= d)
+         {
+         high -= d;
+         quotient |= mask;
+         }
+      }
+   return quotient;
+   }
+
+/*************************************************
+* Do a 2-word/1-word Modulo                      *
+*************************************************/
+word bigint_modop(word n1, word n0, word d)
+   {
+   word z = bigint_divop(n1, n0, d);
+   word dummy = 0;
+   z = word_madd2(z, d, 0, &dummy);
+   return (n0-z);
+   }
+
+/*************************************************
+* Do a word*word->2-word Multiply                *
+*************************************************/
+void bigint_wordmul(word a, word b, word* out_low, word* out_high)
+   {
+   const u32bit MP_HWORD_BITS = MP_WORD_BITS / 2;
+   const word MP_HWORD_MASK = ((word)1 << MP_HWORD_BITS) - 1;
+
+   const word a_hi = (a >> MP_HWORD_BITS);
+   const word a_lo = (a & MP_HWORD_MASK);
+   const word b_hi = (b >> MP_HWORD_BITS);
+   const word b_lo = (b & MP_HWORD_MASK);
+
+   word x0 = a_hi * b_hi;
+   word x1 = a_lo * b_hi;
+   word x2 = a_hi * b_lo;
+   word x3 = a_lo * b_lo;
+
+   x2 += x3 >> (MP_HWORD_BITS);
+   x2 += x1;
+   if(x2 < x1)
+      x0 += ((word)1 << MP_HWORD_BITS);
+
+   *out_high = x0 + (x2 >> MP_HWORD_BITS);
+   *out_low = ((x2 & MP_HWORD_MASK) << MP_HWORD_BITS) + (x3 & MP_HWORD_MASK);
+   }
+
+}
+
+}