diff bn_mp_fread.c @ 282:91fbc376f010 libtommath-orig libtommath-0.35

Import of libtommath 0.35 From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:16:18 +0000
parents
children 97db060d0ef5
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bn_mp_fread.c	Wed Mar 08 13:16:18 2006 +0000
@@ -0,0 +1,63 @@
+#include <tommath.h>
+#ifdef BN_MP_FREAD_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://math.libtomcrypt.org
+ */
+
+/* read a bigint from a file stream in ASCII */
+int mp_fread(mp_int *a, int radix, FILE *stream)
+{
+   int err, ch, neg, y;
+   
+   /* clear a */
+   mp_zero(a);
+   
+   /* if first digit is - then set negative */
+   ch = fgetc(stream);
+   if (ch == '-') {
+      neg = MP_NEG;
+      ch = fgetc(stream);
+   } else {
+      neg = MP_ZPOS;
+   }
+   
+   for (;;) {
+      /* find y in the radix map */
+      for (y = 0; y < radix; y++) {
+          if (mp_s_rmap[y] == ch) {
+             break;
+          }
+      }
+      if (y == radix) {
+         break;
+      }
+      
+      /* shift up and add */
+      if ((err = mp_mul_d(a, radix, a)) != MP_OKAY) {
+         return err;
+      }
+      if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
+         return err;
+      }
+      
+      ch = fgetc(stream);
+   }
+   if (mp_cmp_d(a, 0) != MP_EQ) {
+      a->sign = neg;
+   }
+   
+   return MP_OKAY;
+}
+
+#endif