Cleanup BigInt::cmp

Move bigint_divcore to divide.cpp which is the only place it is
used. Probably not computationally intensive enough to really be worth
optimizing in asm.

2 files changed, 38 insertions, 7 deletions

diff --git a/src/math/bigint/bigint.cpp b/src/math/bigint/bigint.cpp
index 7ff1183a3..45c351256 100644
--- a/src/math/bigint/bigint.cpp
+++ b/src/math/bigint/bigint.cpp
@@ -107,16 +107,23 @@ void BigInt::grow_to(size_t n)
 /*
 * Comparison Function
 */
-s32bit BigInt::cmp(const BigInt& n, bool check_signs) const
+s32bit BigInt::cmp(const BigInt& other, bool check_signs) const
    {
    if(check_signs)
       {
-      if(n.is_positive() && this->is_negative()) return -1;
-      if(n.is_negative() && this->is_positive()) return 1;
-      if(n.is_negative() && this->is_negative())
-         return (-bigint_cmp(data(), sig_words(), n.data(), n.sig_words()));
+      if(other.is_positive() && this->is_negative())
+         return -1;
+
+      if(other.is_negative() && this->is_positive())
+         return 1;
+
+      if(other.is_negative() && this->is_negative())
+         return (-bigint_cmp(this->data(), this->sig_words(),
+                             other.data(), other.sig_words()));
       }
-   return bigint_cmp(data(), sig_words(), n.data(), n.sig_words());
+
+   return bigint_cmp(this->data(), this->sig_words(),
+                     other.data(), other.sig_words());
    }
 
 /*
diff --git a/src/math/bigint/divide.cpp b/src/math/bigint/divide.cpp
index c54eb463b..c8b82422a 100644
--- a/src/math/bigint/divide.cpp
+++ b/src/math/bigint/divide.cpp
@@ -7,6 +7,7 @@
 
 #include <botan/divide.h>
 #include <botan/internal/mp_core.h>
+#include <botan/internal/mp_asmi.h>
 
 namespace Botan {
 
@@ -26,6 +27,29 @@ void sign_fixup(const BigInt& x, const BigInt& y, BigInt& q, BigInt& r)
       q.flip_sign();
    }
 
+bool division_check(word q, word y2, word y1,
+                    word x3, word x2, word x1)
+   {
+   // Compute (y3,y2,y1) = (y2,y1) * q
+
+   word y3 = 0;
+   y1 = word_madd2(q, y1, &y3);
+   y2 = word_madd2(q, y2, &y3);
+
+   // Return (y3,y2,y1) >? (x3,x2,x1)
+
+   if(y3 > x3) return true;
+   if(y3 < x3) return false;
+
+   if(y2 > x2) return true;
+   if(y2 < x2) return false;
+
+   if(y1 > x1) return true;
+   if(y1 < x1) return false;
+
+   return false;
+   }
+
 }
 
 /*
@@ -92,7 +116,7 @@ void divide(const BigInt& x, const BigInt& y_arg, BigInt& q, BigInt& r)
          else
             q_words[j-t-1] = bigint_divop(x_j0, x_j1, y_t);
 
-         while(bigint_divcore(q_words[j-t-1],
+         while(division_check(q_words[j-t-1],
                               y_t, y.word_at(t-1),
                               x_j0, x_j1, r.word_at(j-2)))
             {