--- a/libtommath/bn_mp_lshd.c	Wed Feb 28 22:11:39 2018 +0800
+++ b/libtommath/bn_mp_lshd.c	Thu Oct 15 19:55:15 2020 +0800
@@ -1,67 +1,51 @@
-#include <tommath_private.h>
+#include "tommath_private.h"
 #ifdef BN_MP_LSHD_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 */
 
 /* shift left a certain amount of digits */
-int mp_lshd (mp_int * a, int b)
+mp_err mp_lshd(mp_int *a, int b)
 {
-  int     x, res;
-
-  /* if its less than zero return */
-  if (b <= 0) {
-    return MP_OKAY;
-  }
+   int x;
+   mp_err err;
+   mp_digit *top, *bottom;
 
-  /* grow to fit the new digits */
-  if (a->alloc < (a->used + b)) {
-     if ((res = mp_grow (a, a->used + b)) != MP_OKAY) {
-       return res;
-     }
-  }
+   /* if its less than zero return */
+   if (b <= 0) {
+      return MP_OKAY;
+   }
+   /* no need to shift 0 around */
+   if (MP_IS_ZERO(a)) {
+      return MP_OKAY;
+   }
 
-  {
-    mp_digit *top, *bottom;
-
-    /* increment the used by the shift amount then copy upwards */
-    a->used += b;
+   /* grow to fit the new digits */
+   if (a->alloc < (a->used + b)) {
+      if ((err = mp_grow(a, a->used + b)) != MP_OKAY) {
+         return err;
+      }
+   }
 
-    /* top */
-    top = a->dp + a->used - 1;
+   /* increment the used by the shift amount then copy upwards */
+   a->used += b;
 
-    /* base */
-    bottom = (a->dp + a->used - 1) - b;
+   /* top */
+   top = a->dp + a->used - 1;
+
+   /* base */
+   bottom = (a->dp + a->used - 1) - b;
 
-    /* much like mp_rshd this is implemented using a sliding window
-     * except the window goes the otherway around.  Copying from
-     * the bottom to the top.  see bn_mp_rshd.c for more info.
-     */
-    for (x = a->used - 1; x >= b; x--) {
+   /* much like mp_rshd this is implemented using a sliding window
+    * except the window goes the otherway around.  Copying from
+    * the bottom to the top.  see bn_mp_rshd.c for more info.
+    */
+   for (x = a->used - 1; x >= b; x--) {
       *top-- = *bottom--;
-    }
+   }
 
-    /* zero the lower digits */
-    top = a->dp;
-    for (x = 0; x < b; x++) {
-      *top++ = 0;
-    }
-  }
-  return MP_OKAY;
+   /* zero the lower digits */
+   MP_ZERO_DIGITS(a->dp, b);
+
+   return MP_OKAY;
 }
 #endif
-
-/* ref:         $Format:%D$ */
-/* git commit:  $Format:%H$ */
-/* commit time: $Format:%ai$ */