--- a/libtommath/bn_mp_neg.c	Wed Feb 28 22:11:39 2018 +0800
+++ b/libtommath/bn_mp_neg.c	Thu Oct 15 19:55:15 2020 +0800
@@ -1,40 +1,24 @@
-#include <tommath_private.h>
+#include "tommath_private.h"
 #ifdef BN_MP_NEG_C
-/* LibTomMath, multiple-precision integer library -- Tom St Denis
- *
- * LibTomMath is a library that provides multiple-precision
- * integer arithmetic as well as number theoretic functionality.
- *
- * The library was designed directly after the MPI library by
- * Michael Fromberger but has been written from scratch with
- * additional optimizations in place.
- *
- * The library is free for all purposes without any express
- * guarantee it works.
- *
- * Tom St Denis, [email protected], http://libtom.org
- */
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
 
 /* b = -a */
-int mp_neg (mp_int * a, mp_int * b)
+mp_err mp_neg(const mp_int *a, mp_int *b)
 {
-  int     res;
-  if (a != b) {
-     if ((res = mp_copy (a, b)) != MP_OKAY) {
-        return res;
-     }
-  }
+   mp_err err;
+   if (a != b) {
+      if ((err = mp_copy(a, b)) != MP_OKAY) {
+         return err;
+      }
+   }
 
-  if (mp_iszero(b) != MP_YES) {
-     b->sign = (a->sign == MP_ZPOS) ? MP_NEG : MP_ZPOS;
-  } else {
-     b->sign = MP_ZPOS;
-  }
+   if (!MP_IS_ZERO(b)) {
+      b->sign = (a->sign == MP_ZPOS) ? MP_NEG : MP_ZPOS;
+   } else {
+      b->sign = MP_ZPOS;
+   }
 
-  return MP_OKAY;
+   return MP_OKAY;
 }
 #endif
-
-/* ref:         $Format:%D$ */
-/* git commit:  $Format:%H$ */
-/* commit time: $Format:%ai$ */