1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include <tommath.h> 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef BN_MP_SQRT_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/* this function is less generic than mp_n_root, simpler and faster */ 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint mp_sqrt(mp_int *arg, mp_int *ret) 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int res; 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_int t1,t2; 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* must be positive */ 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (arg->sign == MP_NEG) { 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return MP_VAL; 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* easy out */ 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_iszero(arg) == MP_YES) { 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_zero(ret); 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return MP_OKAY; 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_init_copy(&t1, arg)) != MP_OKAY) { 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_init(&t2)) != MP_OKAY) { 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E2; 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* First approx. (not very bad for large arg) */ 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_rshd (&t1,t1.used/2); 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* t1 > 0 */ 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_div(arg,&t1,&t2,NULL)) != MP_OKAY) { 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E1; 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_add(&t1,&t2,&t1)) != MP_OKAY) { 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E1; 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_div_2(&t1,&t1)) != MP_OKAY) { 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E1; 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* And now t1 > sqrt(arg) */ 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project do { 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_div(arg,&t1,&t2,NULL)) != MP_OKAY) { 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E1; 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_add(&t1,&t2,&t1)) != MP_OKAY) { 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E1; 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((res = mp_div_2(&t1,&t1)) != MP_OKAY) { 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto E1; 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* t1 >= sqrt(arg) >= t2 at this point */ 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } while (mp_cmp_mag(&t1,&t2) == MP_GT); 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project mp_exch(&t1,ret); 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source ProjectE1: mp_clear(&t2); 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source ProjectE2: mp_clear(&t1); 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 77f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 78f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 79f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtommath/bn_mp_sqrt.c,v $ */ 80f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.3 $ */ 81f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:18:44 $ */ 82