1 files changed, 49 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_div_2.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_div_2.c
new file mode 100644
index 00000000000..f56ea819992
--- /dev/null
+++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_div_2.c
@@ -0,0 +1,49 @@
+#include "tommath_private.h"
+#ifdef BN_MP_DIV_2_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+/* b = a/2 */
+mp_err mp_div_2(const mp_int *a, mp_int *b)
+{
+   int     x, oldused;
+   mp_digit r, rr, *tmpa, *tmpb;
+   mp_err err;
+
+   /* copy */
+   if (b->alloc < a->used) {
+      if ((err = mp_grow(b, a->used)) != MP_OKAY) {
+         return err;
+      }
+   }
+
+   oldused = b->used;
+   b->used = a->used;
+
+   /* source alias */
+   tmpa = a->dp + b->used - 1;
+
+   /* dest alias */
+   tmpb = b->dp + b->used - 1;
+
+   /* carry */
+   r = 0;
+   for (x = b->used - 1; x >= 0; x--) {
+      /* get the carry for the next iteration */
+      rr = *tmpa & 1u;
+
+      /* shift the current digit, add in carry and store */
+      *tmpb-- = (*tmpa-- >> 1) | (r << (MP_DIGIT_BIT - 1));
+
+      /* forward carry to next iteration */
+      r = rr;
+   }
+
+   /* zero excess digits */
+   MP_ZERO_DIGITS(b->dp + b->used, oldused - b->used);
+
+   b->sign = a->sign;
+   mp_clamp(b);
+   return MP_OKAY;
+}
+#endif