Import code from previous AssetBuilder version

2025-07-02 01:01:54 +00:00 · 2019-09-24 10:45:09 +02:00
parent 5609557516
commit 0d8432d4f7
919 changed files with 154412 additions and 26 deletions
--- a/thirdparty/libtommath/bn_mp_montgomery_reduce.c
+++ b/thirdparty/libtommath/bn_mp_montgomery_reduce.c
@ -0,0 +1,115 @@
+#include "tommath_private.h"
+#ifdef BN_MP_MONTGOMERY_REDUCE_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
+ */
+
+/* computes xR**-1 == x (mod N) via Montgomery Reduction */
+int mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho)
+{
+   int     ix, res, digs;
+   mp_digit mu;
+
+   /* can the fast reduction [comba] method be used?
+    *
+    * Note that unlike in mul you're safely allowed *less*
+    * than the available columns [255 per default] since carries
+    * are fixed up in the inner loop.
+    */
+   digs = (n->used * 2) + 1;
+   if ((digs < (int)MP_WARRAY) &&
+       (x->used <= (int)MP_WARRAY) &&
+       (n->used <
+        (int)(1u << (((size_t)CHAR_BIT * sizeof(mp_word)) - (2u * (size_t)DIGIT_BIT))))) {
+      return fast_mp_montgomery_reduce(x, n, rho);
+   }
+
+   /* grow the input as required */
+   if (x->alloc < digs) {
+      if ((res = mp_grow(x, digs)) != MP_OKAY) {
+         return res;
+      }
+   }
+   x->used = digs;
+
+   for (ix = 0; ix < n->used; ix++) {
+      /* mu = ai * rho mod b
+       *
+       * The value of rho must be precalculated via
+       * montgomery_setup() such that
+       * it equals -1/n0 mod b this allows the
+       * following inner loop to reduce the
+       * input one digit at a time
+       */
+      mu = (mp_digit)(((mp_word)x->dp[ix] * (mp_word)rho) & MP_MASK);
+
+      /* a = a + mu * m * b**i */
+      {
+         int iy;
+         mp_digit *tmpn, *tmpx, u;
+         mp_word r;
+
+         /* alias for digits of the modulus */
+         tmpn = n->dp;
+
+         /* alias for the digits of x [the input] */
+         tmpx = x->dp + ix;
+
+         /* set the carry to zero */
+         u = 0;
+
+         /* Multiply and add in place */
+         for (iy = 0; iy < n->used; iy++) {
+            /* compute product and sum */
+            r       = ((mp_word)mu * (mp_word)*tmpn++) +
+                      (mp_word)u + (mp_word)*tmpx;
+
+            /* get carry */
+            u       = (mp_digit)(r >> (mp_word)DIGIT_BIT);
+
+            /* fix digit */
+            *tmpx++ = (mp_digit)(r & (mp_word)MP_MASK);
+         }
+         /* At this point the ix'th digit of x should be zero */
+
+
+         /* propagate carries upwards as required*/
+         while (u != 0u) {
+            *tmpx   += u;
+            u        = *tmpx >> DIGIT_BIT;
+            *tmpx++ &= MP_MASK;
+         }
+      }
+   }
+
+   /* at this point the n.used'th least
+    * significant digits of x are all zero
+    * which means we can shift x to the
+    * right by n.used digits and the
+    * residue is unchanged.
+    */
+
+   /* x = x/b**n.used */
+   mp_clamp(x);
+   mp_rshd(x, n->used);
+
+   /* if x >= n then x = x - n */
+   if (mp_cmp_mag(x, n) != MP_LT) {
+      return s_mp_sub(x, n, x);
+   }
+
+   return MP_OKAY;
+}
+#endif
+
+/* ref:         HEAD -> master, tag: v1.1.0 */
+/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */