--- a/libtommath/bn_mp_exteuclid.c	Wed Feb 28 22:11:39 2018 +0800
+++ b/libtommath/bn_mp_exteuclid.c	Thu Oct 15 19:55:15 2020 +0800
@@ -1,75 +1,69 @@
-#include <tommath_private.h>
+#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.
- *
- * 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 */
 
 /* Extended euclidean algorithm of (a, b) produces
    a*u1 + b*u2 = u3
  */
-int mp_exteuclid(mp_int *a, 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_int u1, u2, u3, v1, v2, v3, t1, t2, t3, q, tmp;
+   mp_err err;
 
    if ((err = mp_init_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL)) != MP_OKAY) {
       return err;
    }
 
    /* initialize, (u1,u2,u3) = (1,0,a) */
-   mp_set(&u1, 1);
-   if ((err = mp_copy(a, &u3)) != MP_OKAY)                                        { goto LBL_ERR; }
+   mp_set(&u1, 1uL);
+   if ((err = mp_copy(a, &u3)) != MP_OKAY)                        goto LBL_ERR;
 
    /* initialize, (v1,v2,v3) = (0,1,b) */
-   mp_set(&v2, 1);
-   if ((err = mp_copy(b, &v3)) != MP_OKAY)                                        { goto LBL_ERR; }
+   mp_set(&v2, 1uL);
+   if ((err = mp_copy(b, &v3)) != MP_OKAY)                        goto LBL_ERR;
 
    /* loop while v3 != 0 */
-   while (mp_iszero(&v3) == MP_NO) {
-       /* q = u3/v3 */
-       if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY)                         { goto LBL_ERR; }
+   while (!MP_IS_ZERO(&v3)) {
+      /* q = u3/v3 */
+      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; }
+      /* (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;
 
-       /* (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; }
+      /* (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;
 
-       /* (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; }
+      /* (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;
    }
 
    /* 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 */
-   if (U1 != NULL) { mp_exch(U1, &u1); }
-   if (U2 != NULL) { mp_exch(U2, &u2); }
-   if (U3 != NULL) { mp_exch(U3, &u3); }
+   if (U1 != NULL) {
+      mp_exch(U1, &u1);
+   }
+   if (U2 != NULL) {
+      mp_exch(U2, &u2);
+   }
+   if (U3 != NULL) {
+      mp_exch(U3, &u3);
+   }
 
    err = MP_OKAY;
 LBL_ERR:
@@ -77,7 +71,3 @@
    return err;
 }
 #endif
-
-/* ref:         $Format:%D$ */
-/* git commit:  $Format:%H$ */
-/* commit time: $Format:%ai$ */