1 files changed, 38 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_add.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_add.c
new file mode 100644
index 0000000..dfa78de
--- /dev/null
+++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_add.c
@@ -0,0 +1,38 @@
+#include "tommath_private.h"
+#ifdef BN_MP_ADD_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+/* high level addition (handles signs) */
+mp_err mp_add(const mp_int *a, const mp_int *b, mp_int *c)
+{
+   mp_sign sa, sb;
+   mp_err err;
+
+   /* get sign of both inputs */
+   sa = a->sign;
+   sb = b->sign;
+
+   /* handle two cases, not four */
+   if (sa == sb) {
+      /* both positive or both negative */
+      /* add their magnitudes, copy the sign */
+      c->sign = sa;
+      err = s_mp_add(a, b, c);
+   } else {
+      /* one positive, the other negative */
+      /* subtract the one with the greater magnitude from */
+      /* the one of the lesser magnitude.  The result gets */
+      /* the sign of the one with the greater magnitude. */
+      if (mp_cmp_mag(a, b) == MP_LT) {
+         c->sign = sb;
+         err = s_mp_sub(b, a, c);
+      } else {
+         c->sign = sa;
+         err = s_mp_sub(a, b, c);
+      }
+   }
+   return err;
+}
+
+#endif