2 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 #include "internal/cryptlib.h"
13 BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
27 for (i = a->top - 1; i >= 0; i--) {
29 ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w;
30 ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w;
32 ret = (BN_ULLONG) (((ret << (BN_ULLONG) BN_BITS2) | a->d[i]) %
36 return ((BN_ULONG)ret);
39 BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
48 /* actually this an error (division by zero) */
53 /* normalize input (so bn_div_words doesn't complain) */
54 j = BN_BITS2 - BN_num_bits_word(w);
56 if (!BN_lshift(a, a, j))
59 for (i = a->top - 1; i >= 0; i--) {
63 d = bn_div_words(ret, l, w);
64 ret = (l - ((d * w) & BN_MASK2)) & BN_MASK2;
67 if ((a->top > 0) && (a->d[a->top - 1] == 0))
74 int BN_add_word(BIGNUM *a, BN_ULONG w)
82 /* degenerate case: w is zero */
85 /* degenerate case: a is zero */
87 return BN_set_word(a, w);
88 /* handle 'a' when negative */
91 i = BN_sub_word(a, w);
96 for (i = 0; w != 0 && i < a->top; i++) {
97 a->d[i] = l = (a->d[i] + w) & BN_MASK2;
100 if (w && i == a->top) {
101 if (bn_wexpand(a, a->top + 1) == NULL)
110 int BN_sub_word(BIGNUM *a, BN_ULONG w)
117 /* degenerate case: w is zero */
120 /* degenerate case: a is zero */
122 i = BN_set_word(a, w);
124 BN_set_negative(a, 1);
127 /* handle 'a' when negative */
130 i = BN_add_word(a, w);
135 if ((a->top == 1) && (a->d[0] < w)) {
136 a->d[0] = w - a->d[0];
146 a->d[i] = (a->d[i] - w) & BN_MASK2;
151 if ((a->d[i] == 0) && (i == (a->top - 1)))
157 int BN_mul_word(BIGNUM *a, BN_ULONG w)
167 ll = bn_mul_words(a->d, a->d, a->top, w);
169 if (bn_wexpand(a, a->top + 1) == NULL)