1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include <tommath.h>
2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef BN_MP_GET_INT_C
3f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* LibTomMath, multiple-precision integer library -- Tom St Denis
4f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *
5f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * LibTomMath is a library that provides multiple-precision
6f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * integer arithmetic as well as number theoretic functionality.
7f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *
8f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library was designed directly after the MPI library by
9f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Michael Fromberger but has been written from scratch with
10f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * additional optimizations in place.
11f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *
12f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library is free for all purposes without any express
13f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * guarantee it works.
14f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *
15f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
16f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */
17f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
18f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* get the lower 32-bits of an mp_int */
19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectunsigned long mp_get_int(mp_int * a)
20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{
21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  int i;
22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  unsigned long res;
23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  if (a->used == 0) {
25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project     return 0;
26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  }
27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  /* get number of digits of the lsb we have to read */
29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  i = MIN(a->used,(int)((sizeof(unsigned long)*CHAR_BIT+DIGIT_BIT-1)/DIGIT_BIT))-1;
30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  /* get most significant digit of result */
32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  res = DIGIT(a,i);
33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  while (--i >= 0) {
35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project    res = (res << DIGIT_BIT) | DIGIT(a,i);
36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  }
37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  /* force result to 32-bits always so it is consistent on non 32-bit platforms */
39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project  return res & 0xFFFFFFFFUL;
40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project}
41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif
42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project
43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtommath/bn_mp_get_int.c,v $ */
44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.3 $ */
45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:18:44 $ */
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