Avoid needless alloc and copy

2 files changed, 11 insertions, 7 deletions

diff --git a/src/lib/math/bigint/bigint.h b/src/lib/math/bigint/bigint.h
index 0b826c8f5..8c627c584 100644
--- a/src/lib/math/bigint/bigint.h
+++ b/src/lib/math/bigint/bigint.h
@@ -445,6 +445,12 @@ class BOTAN_PUBLIC_API(2,0) BigInt final
         m_reg[i] = w;
         }
 
+     void set_words(const word w[], size_t len)
+        {
+        m_reg.resize(len);
+        copy_mem(mutable_data(), w, len);
+        }
+
      /**
      * Tests if the sign of the integer is negative
      * @result true, iff the integer has a negative sign
diff --git a/src/lib/pubkey/ec_group/point_gfp.cpp b/src/lib/pubkey/ec_group/point_gfp.cpp
index 5bbef15e7..4c048427f 100644
--- a/src/lib/pubkey/ec_group/point_gfp.cpp
+++ b/src/lib/pubkey/ec_group/point_gfp.cpp
@@ -95,9 +95,8 @@ void PointGFp::add_affine(const word x_words[], size_t x_size,
 
    if(is_zero())
       {
-      // FIXME avoid the copy here
-      m_coord_x = BigInt(x_words, x_size);
-      m_coord_y = BigInt(y_words, y_size);
+      m_coord_x.set_words(x_words, x_size);
+      m_coord_y.set_words(y_words, y_size);
       m_coord_z = m_curve.get_1_rep();
       return;
       }
@@ -178,10 +177,9 @@ void PointGFp::add(const word x_words[], size_t x_size,
 
    if(is_zero())
       {
-      // FIXME avoid the copy here
-      m_coord_x = BigInt(x_words, x_size);
-      m_coord_y = BigInt(y_words, y_size);
-      m_coord_z = BigInt(z_words, z_size);
+      m_coord_x.set_words(x_words, x_size);
+      m_coord_y.set_words(y_words, y_size);
+      m_coord_z.set_words(z_words, z_size);
       return;
       }