Import code from previous AssetBuilder version

thirdparty/libtommath/bn_mp_mod_2d.c

@@ -0,0 +1,51 @@
+#include "tommath_private.h"
+#ifdef BN_MP_MOD_2D_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
+ */
+
+/* calc a value mod 2**b */
+int mp_mod_2d(const mp_int *a, int b, mp_int *c)
+{
+   int     x, res;
+
+   /* if b is <= 0 then zero the int */
+   if (b <= 0) {
+      mp_zero(c);
+      return MP_OKAY;
+   }
+
+   /* if the modulus is larger than the value than return */
+   if (b >= (a->used * DIGIT_BIT)) {
+      res = mp_copy(a, c);
+      return res;
+   }
+
+   /* copy */
+   if ((res = mp_copy(a, c)) != MP_OKAY) {
+      return res;
+   }
+
+   /* zero digits above the last digit of the modulus */
+   for (x = (b / DIGIT_BIT) + (((b % DIGIT_BIT) == 0) ? 0 : 1); x < c->used; x++) {
+      c->dp[x] = 0;
+   }
+   /* clear the digit that is not completely outside/inside the modulus */
+   c->dp[b / DIGIT_BIT] &=
+      ((mp_digit)1 << (mp_digit)(b % DIGIT_BIT)) - (mp_digit)1;
+   mp_clamp(c);
+   return MP_OKAY;
+}
+#endif
+
+/* ref:         HEAD -> master, tag: v1.1.0 */
+/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */