1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include <tommath.h> 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef BN_MP_LSHD_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 left a certain amount of digits */ 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint mp_lshd (mp_int * a, int b) 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int x, res; 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* if its less than zero return */ 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (b <= 0) { 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return MP_OKAY; 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* grow to fit the new digits */ 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (a->alloc < a->used + b) { 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_grow (a, a->used + b)) != MP_OKAY) { 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project { 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project register mp_digit *top, *bottom; 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* increment the used by the shift amount then copy upwards */ 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project a->used += b; 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* top */ 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project top = a->dp + a->used - 1; 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* base */ 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project bottom = a->dp + a->used - 1 - b; 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* much like mp_rshd this is implemented using a sliding window 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * except the window goes the otherway around. Copying from 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * the bottom to the top. see bn_mp_rshd.c for more info. 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */ 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = a->used - 1; x >= b; x--) { 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *top-- = *bottom--; 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* zero the lower digits */ 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project top = a->dp; 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = 0; x < b; x++) { 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *top++ = 0; 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return MP_OKAY; 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtommath/bn_mp_lshd.c,v $ */ 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.3 $ */ 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:18:44 $ */ 68