--- a/libtommath/bn_mp_div_d.c	Tue May 26 23:27:26 2020 +0800
+++ b/libtommath/bn_mp_div_d.c	Tue May 26 17:36:47 2020 +0200
@@ -1,42 +1,16 @@
 #include "tommath_private.h"
 #ifdef BN_MP_DIV_D_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
- */
-
-static int s_is_power_of_two(mp_digit b, int *p)
-{
-   int x;
-
-   /* fast return if no power of two */
-   if ((b == 0u) || ((b & (b-1u)) != 0u)) {
-      return 0;
-   }
-
-   for (x = 0; x < DIGIT_BIT; x++) {
-      if (b == ((mp_digit)1<<(mp_digit)x)) {
-         *p = x;
-         return 1;
-      }
-   }
-   return 0;
-}
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
 
 /* single digit division (based on routine from MPI) */
-int mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d)
+mp_err mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d)
 {
    mp_int  q;
    mp_word w;
    mp_digit t;
-   int     res, ix;
+   mp_err err;
+   int ix;
 
    /* cannot divide by zero */
    if (b == 0u) {
@@ -44,7 +18,7 @@
    }
 
    /* quick outs */
-   if ((b == 1u) || (mp_iszero(a) == MP_YES)) {
+   if ((b == 1u) || MP_IS_ZERO(a)) {
       if (d != NULL) {
          *d = 0;
       }
@@ -55,7 +29,11 @@
    }
 
    /* power of two ? */
-   if (s_is_power_of_two(b, &ix) == 1) {
+   if ((b & (b - 1u)) == 0u) {
+      ix = 1;
+      while ((ix < MP_DIGIT_BIT) && (b != (((mp_digit)1)<<ix))) {
+         ix++;
+      }
       if (d != NULL) {
          *d = a->dp[0] & (((mp_digit)1<<(mp_digit)ix) - 1uL);
       }
@@ -65,23 +43,21 @@
       return MP_OKAY;
    }
 
-#ifdef BN_MP_DIV_3_C
    /* three? */
-   if (b == 3u) {
+   if (MP_HAS(MP_DIV_3) && (b == 3u)) {
       return mp_div_3(a, c, d);
    }
-#endif
 
    /* no easy answer [c'est la vie].  Just division */
-   if ((res = mp_init_size(&q, a->used)) != MP_OKAY) {
-      return res;
+   if ((err = mp_init_size(&q, a->used)) != MP_OKAY) {
+      return err;
    }
 
    q.used = a->used;
    q.sign = a->sign;
    w = 0;
    for (ix = a->used - 1; ix >= 0; ix--) {
-      w = (w << (mp_word)DIGIT_BIT) | (mp_word)a->dp[ix];
+      w = (w << (mp_word)MP_DIGIT_BIT) | (mp_word)a->dp[ix];
 
       if (w >= b) {
          t = (mp_digit)(w / b);
@@ -102,11 +78,7 @@
    }
    mp_clear(&q);
 
-   return res;
+   return err;
 }
 
 #endif
-
-/* ref:         HEAD -> master, tag: v1.1.0 */
-/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
-/* commit time: 2019-01-28 20:32:32 +0100 */