Add BigInt::operator*= taking a word

Avoids memory allocation when multiplying by a small constant.

1 files changed, 17 insertions, 2 deletions

diff --git a/src/lib/math/bigint/big_ops2.cpp b/src/lib/math/bigint/big_ops2.cpp
index 2f81989c3..7653884c9 100644
--- a/src/lib/math/bigint/big_ops2.cpp
+++ b/src/lib/math/bigint/big_ops2.cpp
@@ -107,12 +107,12 @@ BigInt& BigInt::operator*=(const BigInt& y)
       }
    else if(x_sw == 1 && y_sw)
       {
-      grow_to(y_sw + 2);
+      grow_to(y_sw + 1);
       bigint_linmul3(mutable_data(), y.data(), y_sw, word_at(0));
       }
    else if(y_sw == 1 && x_sw)
       {
-      grow_to(x_sw + 2);
+      grow_to(x_sw + 1);
       bigint_linmul2(mutable_data(), x_sw, y.word_at(0));
       }
    else
@@ -125,6 +125,21 @@ BigInt& BigInt::operator*=(const BigInt& y)
    return (*this);
    }
 
+BigInt& BigInt::operator*=(word y)
+   {
+   if(y == 0)
+      {
+      clear();
+      set_sign(Positive);
+      }
+
+   const size_t x_sw = sig_words();
+   grow_to(x_sw + 1);
+   bigint_linmul2(mutable_data(), x_sw, y);
+
+   return (*this);
+   }
+
 /*
 * Division Operator
 */