--- a/libtommath/bn_mp_mod_2d.c	Tue May 26 23:27:26 2020 +0800
+++ b/libtommath/bn_mp_mod_2d.c	Tue May 26 17:36:47 2020 +0200
@@ -1,21 +1,13 @@
 #include "tommath_private.h"
 #ifdef BN_MP_MOD_2D_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.
- *
- * SPDX-License-Identifier: Unlicense
- */
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
 
 /* calc a value mod 2**b */
-int mp_mod_2d(const mp_int *a, int b, mp_int *c)
+mp_err mp_mod_2d(const mp_int *a, int b, mp_int *c)
 {
-   int     x, res;
+   int x;
+   mp_err err;
 
    /* if b is <= 0 then zero the int */
    if (b <= 0) {
@@ -24,28 +16,23 @@
    }
 
    /* if the modulus is larger than the value than return */
-   if (b >= (a->used * DIGIT_BIT)) {
-      res = mp_copy(a, c);
-      return res;
+   if (b >= (a->used * MP_DIGIT_BIT)) {
+      return mp_copy(a, c);
    }
 
    /* copy */
-   if ((res = mp_copy(a, c)) != MP_OKAY) {
-      return res;
+   if ((err = mp_copy(a, c)) != MP_OKAY) {
+      return err;
    }
 
    /* zero digits above the last digit of the modulus */
-   for (x = (b / DIGIT_BIT) + (((b % DIGIT_BIT) == 0) ? 0 : 1); x < c->used; x++) {
-      c->dp[x] = 0;
-   }
+   x = (b / MP_DIGIT_BIT) + (((b % MP_DIGIT_BIT) == 0) ? 0 : 1);
+   MP_ZERO_DIGITS(c->dp + x, c->used - x);
+
    /* clear the digit that is not completely outside/inside the modulus */
-   c->dp[b / DIGIT_BIT] &=
-      ((mp_digit)1 << (mp_digit)(b % DIGIT_BIT)) - (mp_digit)1;
+   c->dp[b / MP_DIGIT_BIT] &=
+      ((mp_digit)1 << (mp_digit)(b % MP_DIGIT_BIT)) - (mp_digit)1;
    mp_clamp(c);
    return MP_OKAY;
 }
 #endif
-
-/* ref:         HEAD -> master, tag: v1.1.0 */
-/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
-/* commit time: 2019-01-28 20:32:32 +0100 */