1 files changed, 28 insertions, 0 deletions
diff --git a/mpi/mpiutil.c b/mpi/mpiutil.c
index 3a1d71fb4..8b2071afc 100644
--- a/mpi/mpiutil.c
+++ b/mpi/mpiutil.c
@@ -433,6 +433,34 @@ mpi_set( MPI w, MPI u)
 
 
 void
+mpi_set_cond( MPI w, MPI u, unsigned long set)
+{
+    mpi_size_t i;
+    mpi_size_t nlimbs = u->alloced;
+    mpi_limb_t mask = ((mpi_limb_t)0) - !!set;
+    mpi_limb_t x;
+
+    if (w->alloced != u->alloced)
+      log_bug ("mpi_set_cond: different sizes\n");
+
+    for (i = 0; i < nlimbs; i++)
+      {
+        x = mask & (w->d[i] ^ u->d[i]);
+        w->d[i] = w->d[i] ^ x;
+      }
+
+    x = mask & (w->nlimbs ^ u->nlimbs);
+    w->nlimbs = w->nlimbs ^ x;
+
+    x = mask & (w->nbits ^ u->nbits);
+    w->nbits = w->nbits ^ x;
+
+    x = mask & (w->sign ^ u->sign);
+    w->sign = w->sign ^ x;
+}
+
+
+void
 mpi_set_ui( MPI w, unsigned long u)
 {
     RESIZE_IF_NEEDED(w, 1);