1/* mpi-inline.h - Internal to the Multi Precision Integers 2 * Copyright (C) 1994, 1996, 1998, 1999 Free Software Foundation, Inc. 3 * 4 * This file is part of GnuPG. 5 * 6 * GnuPG is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * GnuPG is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 19 * 20 * Note: This code is heavily based on the GNU MP Library. 21 * Actually it's the same code with only minor changes in the 22 * way the data is stored; this is to support the abstraction 23 * of an optional secure memory allocation which may be used 24 * to avoid revealing of sensitive data due to paging etc. 25 * The GNU MP Library itself is published under the LGPL; 26 * however I decided to publish this code under the plain GPL. 27 */ 28 29#ifndef G10_MPI_INLINE_H 30#define G10_MPI_INLINE_H 31 32#ifndef G10_MPI_INLINE_DECL 33#define G10_MPI_INLINE_DECL extern inline 34#endif 35 36G10_MPI_INLINE_DECL mpi_limb_t 37mpihelp_add_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, 38 mpi_size_t s1_size, mpi_limb_t s2_limb) 39{ 40 mpi_limb_t x; 41 42 x = *s1_ptr++; 43 s2_limb += x; 44 *res_ptr++ = s2_limb; 45 if (s2_limb < x) { /* sum is less than the left operand: handle carry */ 46 while (--s1_size) { 47 x = *s1_ptr++ + 1; /* add carry */ 48 *res_ptr++ = x; /* and store */ 49 if (x) /* not 0 (no overflow): we can stop */ 50 goto leave; 51 } 52 return 1; /* return carry (size of s1 to small) */ 53 } 54 55leave: 56 if (res_ptr != s1_ptr) { /* not the same variable */ 57 mpi_size_t i; /* copy the rest */ 58 for (i = 0; i < s1_size - 1; i++) 59 res_ptr[i] = s1_ptr[i]; 60 } 61 return 0; /* no carry */ 62} 63 64G10_MPI_INLINE_DECL mpi_limb_t 65mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, 66 mpi_ptr_t s2_ptr, mpi_size_t s2_size) 67{ 68 mpi_limb_t cy = 0; 69 70 if (s2_size) 71 cy = mpihelp_add_n(res_ptr, s1_ptr, s2_ptr, s2_size); 72 73 if (s1_size - s2_size) 74 cy = mpihelp_add_1(res_ptr + s2_size, s1_ptr + s2_size, 75 s1_size - s2_size, cy); 76 return cy; 77} 78 79G10_MPI_INLINE_DECL mpi_limb_t 80mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, 81 mpi_size_t s1_size, mpi_limb_t s2_limb) 82{ 83 mpi_limb_t x; 84 85 x = *s1_ptr++; 86 s2_limb = x - s2_limb; 87 *res_ptr++ = s2_limb; 88 if (s2_limb > x) { 89 while (--s1_size) { 90 x = *s1_ptr++; 91 *res_ptr++ = x - 1; 92 if (x) 93 goto leave; 94 } 95 return 1; 96 } 97 98leave: 99 if (res_ptr != s1_ptr) { 100 mpi_size_t i; 101 for (i = 0; i < s1_size - 1; i++) 102 res_ptr[i] = s1_ptr[i]; 103 } 104 return 0; 105} 106 107G10_MPI_INLINE_DECL mpi_limb_t 108mpihelp_sub(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size, 109 mpi_ptr_t s2_ptr, mpi_size_t s2_size) 110{ 111 mpi_limb_t cy = 0; 112 113 if (s2_size) 114 cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size); 115 116 if (s1_size - s2_size) 117 cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size, 118 s1_size - s2_size, cy); 119 return cy; 120} 121 122#endif /*G10_MPI_INLINE_H */ 123