Remove BigInt::operator[]. Use BigInt::word_at, which checks sizes

4 files changed, 12 insertions, 14 deletions

diff --git a/src/math/bigint/bigint.h b/src/math/bigint/bigint.h
index 6efe53e71..a74a5c280 100644
--- a/src/math/bigint/bigint.h
+++ b/src/math/bigint/bigint.h
@@ -124,13 +124,6 @@ class BOTAN_DLL BigInt
      bool operator !() const { return (!is_nonzero()); }
 
      /**
-     * [] operator (array access)
-     * @param i a word index
-     * @return the word at index i
-     */
-     const word& operator[](size_t i) const { return m_reg[i]; }
-
-     /**
      * Zeroize the BigInt. The size of the underlying register is not
      * modified.
      */
diff --git a/src/math/bigint/divide.cpp b/src/math/bigint/divide.cpp
index e6d768b1c..c54eb463b 100644
--- a/src/math/bigint/divide.cpp
+++ b/src/math/bigint/divide.cpp
@@ -1,6 +1,6 @@
 /*
 * Division Algorithm
-* (C) 1999-2007 Jack Lloyd
+* (C) 1999-2007,2012 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
 */
@@ -55,7 +55,7 @@ void divide(const BigInt& x, const BigInt& y_arg, BigInt& q, BigInt& r)
    else if(compare > 0)
       {
       size_t shifts = 0;
-      word y_top = y[y.sig_words()-1];
+      word y_top = y.word_at(y.sig_words()-1);
       while(y_top < MP_WORD_TOP_BIT) { y_top <<= 1; ++shifts; }
       y <<= shifts;
       r <<= shifts;
@@ -92,11 +92,15 @@ 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[j-t-1], y_t, y.word_at(t-1),
+         while(bigint_divcore(q_words[j-t-1],
+                              y_t, y.word_at(t-1),
                               x_j0, x_j1, r.word_at(j-2)))
+            {
             q_words[j-t-1] -= 1;
+            }
+
+         r -= (q_words[j-t-1] * y) << (MP_WORD_BITS * (j-t-1));
 
-         r -= (q[j-t-1] * y) << (MP_WORD_BITS * (j-t-1));
          if(r.is_negative())
             {
             r += y << (MP_WORD_BITS * (j-t-1));
diff --git a/src/math/numbertheory/numthry.cpp b/src/math/numbertheory/numthry.cpp
index c431fb63f..38d683f1c 100644
--- a/src/math/numbertheory/numthry.cpp
+++ b/src/math/numbertheory/numthry.cpp
@@ -148,7 +148,7 @@ size_t low_zero_bits(const BigInt& n)
       {
       for(size_t i = 0; i != n.size(); ++i)
          {
-         word x = n[i];
+         const word x = n.word_at(i);
 
          if(x)
             {
diff --git a/src/math/numbertheory/numthry.h b/src/math/numbertheory/numthry.h
index d21635f34..7d0330ef6 100644
--- a/src/math/numbertheory/numthry.h
+++ b/src/math/numbertheory/numthry.h
@@ -108,9 +108,10 @@ BigInt BOTAN_DLL power_mod(const BigInt& b,
 BigInt BOTAN_DLL ressol(const BigInt& x, const BigInt& p);
 
 /**
-* @param x an integer
+* @param x a positive integer
 * @return count of the zero bits in x, or, equivalently, the largest
-* value of n such that 2^n divides x evently
+*         value of n such that 2^n divides x evenly. Returns zero if
+*         n is less than or equal to zero.
 */
 size_t BOTAN_DLL low_zero_bits(const BigInt& x);