release/src/router/dropbear/libtommath/bn_mp_read_signed_bin.c

   1 #include <tommath.h>
   2 #ifdef BN_MP_READ_SIGNED_BIN_C
   3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
   4  *
   5  * LibTomMath is a library that provides multiple-precision
   6  * integer arithmetic as well as number theoretic functionality.
   7  *
   8  * The library was designed directly after the MPI library by
   9  * Michael Fromberger but has been written from scratch with
  10  * additional optimizations in place.
  11  *
  12  * The library is free for all purposes without any express
  13  * guarantee it works.
  14  *
  15  * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
  16  */
  17
  18 /* read signed bin, big endian, first byte is 0==positive or 1==negative */
  19 int mp_read_signed_bin (mp_int * a, const unsigned char *b, int c)
  20 {
  21   int     res;
  22
  23   /* read magnitude */
  24   if ((res = mp_read_unsigned_bin (a, b + 1, c - 1)) != MP_OKAY) {
  25     return res;
  26   }
  27
  28   /* first byte is 0 for positive, non-zero for negative */
  29   if (b[0] == 0) {
  30      a->sign = MP_ZPOS;
  31   } else {
  32      a->sign = MP_NEG;
  33   }
  34
  35   return MP_OKAY;
  36 }
  37 #endif
  38
  39 /* $Source: /cvs/libtom/libtommath/bn_mp_read_signed_bin.c,v $ */
  40 /* $Revision: 1.4 $ */
  41 /* $Date: 2006/03/31 14:18:44 $ */