--- a/libtommath/bn_mp_exteuclid.c	Tue May 26 23:27:26 2020 +0800
+++ b/libtommath/bn_mp_exteuclid.c	Tue May 26 17:36:47 2020 +0200
@@ -1,24 +1,15 @@
 #include "tommath_private.h"
 #ifdef BN_MP_EXTEUCLID_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 */
 
 /* Extended euclidean algorithm of (a, b) produces
    a*u1 + b*u2 = u3
  */
-int mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
+mp_err mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
 {
    mp_int u1, u2, u3, v1, v2, v3, t1, t2, t3, q, tmp;
-   int err;
+   mp_err err;
 
    if ((err = mp_init_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL)) != MP_OKAY) {
       return err;
@@ -26,77 +17,41 @@
 
    /* initialize, (u1,u2,u3) = (1,0,a) */
    mp_set(&u1, 1uL);
-   if ((err = mp_copy(a, &u3)) != MP_OKAY) {
-      goto LBL_ERR;
-   }
+   if ((err = mp_copy(a, &u3)) != MP_OKAY)                        goto LBL_ERR;
 
    /* initialize, (v1,v2,v3) = (0,1,b) */
    mp_set(&v2, 1uL);
-   if ((err = mp_copy(b, &v3)) != MP_OKAY) {
-      goto LBL_ERR;
-   }
+   if ((err = mp_copy(b, &v3)) != MP_OKAY)                        goto LBL_ERR;
 
    /* loop while v3 != 0 */
-   while (mp_iszero(&v3) == MP_NO) {
+   while (!MP_IS_ZERO(&v3)) {
       /* q = u3/v3 */
-      if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
+      if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY)          goto LBL_ERR;
 
       /* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */
-      if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
+      if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY)               goto LBL_ERR;
+      if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY)              goto LBL_ERR;
+      if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY)               goto LBL_ERR;
+      if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY)              goto LBL_ERR;
+      if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY)               goto LBL_ERR;
+      if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY)              goto LBL_ERR;
 
       /* (u1,u2,u3) = (v1,v2,v3) */
-      if ((err = mp_copy(&v1, &u1)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_copy(&v2, &u2)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_copy(&v3, &u3)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
+      if ((err = mp_copy(&v1, &u1)) != MP_OKAY)                   goto LBL_ERR;
+      if ((err = mp_copy(&v2, &u2)) != MP_OKAY)                   goto LBL_ERR;
+      if ((err = mp_copy(&v3, &u3)) != MP_OKAY)                   goto LBL_ERR;
 
       /* (v1,v2,v3) = (t1,t2,t3) */
-      if ((err = mp_copy(&t1, &v1)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_copy(&t2, &v2)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_copy(&t3, &v3)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
+      if ((err = mp_copy(&t1, &v1)) != MP_OKAY)                   goto LBL_ERR;
+      if ((err = mp_copy(&t2, &v2)) != MP_OKAY)                   goto LBL_ERR;
+      if ((err = mp_copy(&t3, &v3)) != MP_OKAY)                   goto LBL_ERR;
    }
 
    /* make sure U3 >= 0 */
    if (u3.sign == MP_NEG) {
-      if ((err = mp_neg(&u1, &u1)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_neg(&u2, &u2)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
-      if ((err = mp_neg(&u3, &u3)) != MP_OKAY) {
-         goto LBL_ERR;
-      }
+      if ((err = mp_neg(&u1, &u1)) != MP_OKAY)                    goto LBL_ERR;
+      if ((err = mp_neg(&u2, &u2)) != MP_OKAY)                    goto LBL_ERR;
+      if ((err = mp_neg(&u3, &u3)) != MP_OKAY)                    goto LBL_ERR;
    }
 
    /* copy result out */
@@ -116,7 +71,3 @@
    return err;
 }
 #endif
-
-/* ref:         HEAD -> master, tag: v1.1.0 */
-/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
-/* commit time: 2019-01-28 20:32:32 +0100 */