Import code from previous AssetBuilder version

thirdparty/libtommath/bn_mp_read_radix.c

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+#include "tommath_private.h"
+#ifdef BN_MP_READ_RADIX_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
+ */
+
+/* read a string [ASCII] in a given radix */
+int mp_read_radix(mp_int *a, const char *str, int radix)
+{
+   int     y, res, neg;
+   unsigned pos;
+   char    ch;
+
+   /* zero the digit bignum */
+   mp_zero(a);
+
+   /* make sure the radix is ok */
+   if ((radix < 2) || (radix > 64)) {
+      return MP_VAL;
+   }
+
+   /* if the leading digit is a
+    * minus set the sign to negative.
+    */
+   if (*str == '-') {
+      ++str;
+      neg = MP_NEG;
+   } else {
+      neg = MP_ZPOS;
+   }
+
+   /* set the integer to the default of zero */
+   mp_zero(a);
+
+   /* process each digit of the string */
+   while (*str != '\0') {
+      /* if the radix <= 36 the conversion is case insensitive
+       * this allows numbers like 1AB and 1ab to represent the same  value
+       * [e.g. in hex]
+       */
+      ch = (radix <= 36) ? (char)toupper((int)*str) : *str;
+      pos = (unsigned)(ch - '(');
+      if (mp_s_rmap_reverse_sz < pos) {
+         break;
+      }
+      y = (int)mp_s_rmap_reverse[pos];
+
+      /* if the char was found in the map
+       * and is less than the given radix add it
+       * to the number, otherwise exit the loop.
+       */
+      if ((y == 0xff) || (y >= radix)) {
+         break;
+      }
+      if ((res = mp_mul_d(a, (mp_digit)radix, a)) != MP_OKAY) {
+         return res;
+      }
+      if ((res = mp_add_d(a, (mp_digit)y, a)) != MP_OKAY) {
+         return res;
+      }
+      ++str;
+   }
+
+   /* if an illegal character was found, fail. */
+   if (!((*str == '\0') || (*str == '\r') || (*str == '\n'))) {
+      mp_zero(a);
+      return MP_VAL;
+   }
+
+   /* set the sign only if a != 0 */
+   if (mp_iszero(a) != MP_YES) {
+      a->sign = neg;
+   }
+   return MP_OKAY;
+}
+#endif
+
+/* ref:         HEAD -> master, tag: v1.1.0 */
+/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */