1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include <tommath.h> 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef BN_MP_DIV_2D_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/* shift right by a certain bit count (store quotient in c, optional remainder in d) */ 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint mp_div_2d (mp_int * a, int b, mp_int * c, mp_int * d) 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_digit D, r, rr; 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int x, res; 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_int t; 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* if the shift count is <= 0 then we do no work */ 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (b <= 0) { 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project res = mp_copy (a, c); 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (d != NULL) { 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_zero (d); 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_init (&t)) != MP_OKAY) { 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* get the remainder */ 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (d != NULL) { 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_mod_2d (a, b, &t)) != MP_OKAY) { 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clear (&t); 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* copy */ 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_copy (a, c)) != MP_OKAY) { 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clear (&t); 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* shift by as many digits in the bit count */ 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (b >= (int)DIGIT_BIT) { 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_rshd (c, b / DIGIT_BIT); 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* shift any bit count < DIGIT_BIT */ 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project D = (mp_digit) (b % DIGIT_BIT); 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (D != 0) { 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project register mp_digit *tmpc, mask, shift; 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* mask */ 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mask = (((mp_digit)1) << D) - 1; 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* shift for lsb */ 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project shift = DIGIT_BIT - D; 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* alias */ 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project tmpc = c->dp + (c->used - 1); 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* carry */ 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project r = 0; 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = c->used - 1; x >= 0; x--) { 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* get the lower bits of this word in a temp */ 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project rr = *tmpc & mask; 77f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 78f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* shift the current word and mix in the carry bits from the previous word */ 79f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *tmpc = (*tmpc >> D) | (r << shift); 80f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project --tmpc; 81f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 82f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* set the carry to the carry bits of the current word found above */ 83f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project r = rr; 84f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 85f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 86f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clamp (c); 87f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (d != NULL) { 88f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_exch (&t, d); 89f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 90f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_clear (&t); 91f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return MP_OKAY; 92f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 93f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 94f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 95f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtommath/bn_mp_div_2d.c,v $ */ 96f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.3 $ */ 97f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:18:44 $ */ 98