--- a/libtommath/bn_s_mp_sqr.c	Wed Feb 28 22:11:39 2018 +0800
+++ b/libtommath/bn_s_mp_sqr.c	Thu Oct 15 19:55:15 2020 +0800
@@ -1,84 +1,69 @@
-#include <tommath_private.h>
+#include "tommath_private.h"
 #ifdef BN_S_MP_SQR_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 */
 
 /* low level squaring, b = a*a, HAC pp.596-597, Algorithm 14.16 */
-int s_mp_sqr (mp_int * a, mp_int * b)
+mp_err s_mp_sqr(const mp_int *a, mp_int *b)
 {
-  mp_int  t;
-  int     res, ix, iy, pa;
-  mp_word r;
-  mp_digit u, tmpx, *tmpt;
+   mp_int   t;
+   int      ix, iy, pa;
+   mp_err   err;
+   mp_word  r;
+   mp_digit u, tmpx, *tmpt;
 
-  pa = a->used;
-  if ((res = mp_init_size (&t, (2 * pa) + 1)) != MP_OKAY) {
-    return res;
-  }
-
-  /* default used is maximum possible size */
-  t.used = (2 * pa) + 1;
+   pa = a->used;
+   if ((err = mp_init_size(&t, (2 * pa) + 1)) != MP_OKAY) {
+      return err;
+   }
 
-  for (ix = 0; ix < pa; ix++) {
-    /* first calculate the digit at 2*ix */
-    /* calculate double precision result */
-    r = (mp_word)t.dp[2*ix] +
-        ((mp_word)a->dp[ix] * (mp_word)a->dp[ix]);
+   /* default used is maximum possible size */
+   t.used = (2 * pa) + 1;
+
+   for (ix = 0; ix < pa; ix++) {
+      /* first calculate the digit at 2*ix */
+      /* calculate double precision result */
+      r = (mp_word)t.dp[2*ix] +
+          ((mp_word)a->dp[ix] * (mp_word)a->dp[ix]);
 
-    /* store lower part in result */
-    t.dp[ix+ix] = (mp_digit) (r & ((mp_word) MP_MASK));
+      /* store lower part in result */
+      t.dp[ix+ix] = (mp_digit)(r & (mp_word)MP_MASK);
 
-    /* get the carry */
-    u           = (mp_digit)(r >> ((mp_word) DIGIT_BIT));
+      /* get the carry */
+      u           = (mp_digit)(r >> (mp_word)MP_DIGIT_BIT);
 
-    /* left hand side of A[ix] * A[iy] */
-    tmpx        = a->dp[ix];
+      /* left hand side of A[ix] * A[iy] */
+      tmpx        = a->dp[ix];
 
-    /* alias for where to store the results */
-    tmpt        = t.dp + ((2 * ix) + 1);
-    
-    for (iy = ix + 1; iy < pa; iy++) {
-      /* first calculate the product */
-      r       = ((mp_word)tmpx) * ((mp_word)a->dp[iy]);
+      /* alias for where to store the results */
+      tmpt        = t.dp + ((2 * ix) + 1);
+
+      for (iy = ix + 1; iy < pa; iy++) {
+         /* first calculate the product */
+         r       = (mp_word)tmpx * (mp_word)a->dp[iy];
 
-      /* now calculate the double precision result, note we use
-       * addition instead of *2 since it's easier to optimize
-       */
-      r       = ((mp_word) *tmpt) + r + r + ((mp_word) u);
+         /* now calculate the double precision result, note we use
+          * addition instead of *2 since it's easier to optimize
+          */
+         r       = (mp_word)*tmpt + r + r + (mp_word)u;
 
-      /* store lower part */
-      *tmpt++ = (mp_digit) (r & ((mp_word) MP_MASK));
+         /* store lower part */
+         *tmpt++ = (mp_digit)(r & (mp_word)MP_MASK);
 
-      /* get carry */
-      u       = (mp_digit)(r >> ((mp_word) DIGIT_BIT));
-    }
-    /* propagate upwards */
-    while (u != ((mp_digit) 0)) {
-      r       = ((mp_word) *tmpt) + ((mp_word) u);
-      *tmpt++ = (mp_digit) (r & ((mp_word) MP_MASK));
-      u       = (mp_digit)(r >> ((mp_word) DIGIT_BIT));
-    }
-  }
+         /* get carry */
+         u       = (mp_digit)(r >> (mp_word)MP_DIGIT_BIT);
+      }
+      /* propagate upwards */
+      while (u != 0uL) {
+         r       = (mp_word)*tmpt + (mp_word)u;
+         *tmpt++ = (mp_digit)(r & (mp_word)MP_MASK);
+         u       = (mp_digit)(r >> (mp_word)MP_DIGIT_BIT);
+      }
+   }
 
-  mp_clamp (&t);
-  mp_exch (&t, b);
-  mp_clear (&t);
-  return MP_OKAY;
+   mp_clamp(&t);
+   mp_exch(&t, b);
+   mp_clear(&t);
+   return MP_OKAY;
 }
 #endif
-
-/* ref:         $Format:%D$ */
-/* git commit:  $Format:%H$ */
-/* commit time: $Format:%ai$ */