--- a/libtommath/bn_mp_gcd.c	Tue May 26 23:27:26 2020 +0800
+++ b/libtommath/bn_mp_gcd.c	Tue May 26 17:36:47 2020 +0200
@@ -1,37 +1,29 @@
 #include "tommath_private.h"
 #ifdef BN_MP_GCD_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 */
 
 /* Greatest Common Divisor using the binary method */
-int mp_gcd(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_gcd(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int  u, v;
-   int     k, u_lsb, v_lsb, res;
+   int     k, u_lsb, v_lsb;
+   mp_err err;
 
    /* either zero than gcd is the largest */
-   if (mp_iszero(a) == MP_YES) {
+   if (MP_IS_ZERO(a)) {
       return mp_abs(b, c);
    }
-   if (mp_iszero(b) == MP_YES) {
+   if (MP_IS_ZERO(b)) {
       return mp_abs(a, c);
    }
 
    /* get copies of a and b we can modify */
-   if ((res = mp_init_copy(&u, a)) != MP_OKAY) {
-      return res;
+   if ((err = mp_init_copy(&u, a)) != MP_OKAY) {
+      return err;
    }
 
-   if ((res = mp_init_copy(&v, b)) != MP_OKAY) {
+   if ((err = mp_init_copy(&v, b)) != MP_OKAY) {
       goto LBL_U;
    }
 
@@ -41,33 +33,33 @@
    /* B1.  Find the common power of two for u and v */
    u_lsb = mp_cnt_lsb(&u);
    v_lsb = mp_cnt_lsb(&v);
-   k     = MIN(u_lsb, v_lsb);
+   k     = MP_MIN(u_lsb, v_lsb);
 
    if (k > 0) {
       /* divide the power of two out */
-      if ((res = mp_div_2d(&u, k, &u, NULL)) != MP_OKAY) {
+      if ((err = mp_div_2d(&u, k, &u, NULL)) != MP_OKAY) {
          goto LBL_V;
       }
 
-      if ((res = mp_div_2d(&v, k, &v, NULL)) != MP_OKAY) {
+      if ((err = mp_div_2d(&v, k, &v, NULL)) != MP_OKAY) {
          goto LBL_V;
       }
    }
 
    /* divide any remaining factors of two out */
    if (u_lsb != k) {
-      if ((res = mp_div_2d(&u, u_lsb - k, &u, NULL)) != MP_OKAY) {
+      if ((err = mp_div_2d(&u, u_lsb - k, &u, NULL)) != MP_OKAY) {
          goto LBL_V;
       }
    }
 
    if (v_lsb != k) {
-      if ((res = mp_div_2d(&v, v_lsb - k, &v, NULL)) != MP_OKAY) {
+      if ((err = mp_div_2d(&v, v_lsb - k, &v, NULL)) != MP_OKAY) {
          goto LBL_V;
       }
    }
 
-   while (mp_iszero(&v) == MP_NO) {
+   while (!MP_IS_ZERO(&v)) {
       /* make sure v is the largest */
       if (mp_cmp_mag(&u, &v) == MP_GT) {
          /* swap u and v to make sure v is >= u */
@@ -75,30 +67,26 @@
       }
 
       /* subtract smallest from largest */
-      if ((res = s_mp_sub(&v, &u, &v)) != MP_OKAY) {
+      if ((err = s_mp_sub(&v, &u, &v)) != MP_OKAY) {
          goto LBL_V;
       }
 
       /* Divide out all factors of two */
-      if ((res = mp_div_2d(&v, mp_cnt_lsb(&v), &v, NULL)) != MP_OKAY) {
+      if ((err = mp_div_2d(&v, mp_cnt_lsb(&v), &v, NULL)) != MP_OKAY) {
          goto LBL_V;
       }
    }
 
    /* multiply by 2**k which we divided out at the beginning */
-   if ((res = mp_mul_2d(&u, k, c)) != MP_OKAY) {
+   if ((err = mp_mul_2d(&u, k, c)) != MP_OKAY) {
       goto LBL_V;
    }
    c->sign = MP_ZPOS;
-   res = MP_OKAY;
+   err = MP_OKAY;
 LBL_V:
    mp_clear(&u);
 LBL_U:
    mp_clear(&v);
-   return res;
+   return err;
 }
 #endif
-
-/* ref:         HEAD -> master, tag: v1.1.0 */
-/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
-/* commit time: 2019-01-28 20:32:32 +0100 */