| /* |
| * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. |
| * |
| * Licensed under the OpenSSL license (the "License"). You may not use |
| * this file except in compliance with the License. You can obtain a copy |
| * in the file LICENSE in the source distribution or at |
| * https://www.openssl.org/source/license.html |
| */ |
| |
| #include "internal/cryptlib.h" |
| #include "bn_lcl.h" |
| |
| int BN_lshift1(BIGNUM *r, const BIGNUM *a) |
| { |
| register BN_ULONG *ap, *rp, t, c; |
| int i; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| if (r != a) { |
| r->neg = a->neg; |
| if (bn_wexpand(r, a->top + 1) == NULL) |
| return (0); |
| r->top = a->top; |
| } else { |
| if (bn_wexpand(r, a->top + 1) == NULL) |
| return (0); |
| } |
| ap = a->d; |
| rp = r->d; |
| c = 0; |
| for (i = 0; i < a->top; i++) { |
| t = *(ap++); |
| *(rp++) = ((t << 1) | c) & BN_MASK2; |
| c = (t & BN_TBIT) ? 1 : 0; |
| } |
| if (c) { |
| *rp = 1; |
| r->top++; |
| } |
| bn_check_top(r); |
| return (1); |
| } |
| |
| int BN_rshift1(BIGNUM *r, const BIGNUM *a) |
| { |
| BN_ULONG *ap, *rp, t, c; |
| int i, j; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| if (BN_is_zero(a)) { |
| BN_zero(r); |
| return (1); |
| } |
| i = a->top; |
| ap = a->d; |
| j = i - (ap[i - 1] == 1); |
| if (a != r) { |
| if (bn_wexpand(r, j) == NULL) |
| return (0); |
| r->neg = a->neg; |
| } |
| rp = r->d; |
| t = ap[--i]; |
| c = (t & 1) ? BN_TBIT : 0; |
| if (t >>= 1) |
| rp[i] = t; |
| while (i > 0) { |
| t = ap[--i]; |
| rp[i] = ((t >> 1) & BN_MASK2) | c; |
| c = (t & 1) ? BN_TBIT : 0; |
| } |
| r->top = j; |
| if (!r->top) |
| r->neg = 0; /* don't allow negative zero */ |
| bn_check_top(r); |
| return (1); |
| } |
| |
| int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) |
| { |
| int i, nw, lb, rb; |
| BN_ULONG *t, *f; |
| BN_ULONG l; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| if (n < 0) { |
| BNerr(BN_F_BN_LSHIFT, BN_R_INVALID_SHIFT); |
| return 0; |
| } |
| |
| nw = n / BN_BITS2; |
| if (bn_wexpand(r, a->top + nw + 1) == NULL) |
| return (0); |
| r->neg = a->neg; |
| lb = n % BN_BITS2; |
| rb = BN_BITS2 - lb; |
| f = a->d; |
| t = r->d; |
| t[a->top + nw] = 0; |
| if (lb == 0) |
| for (i = a->top - 1; i >= 0; i--) |
| t[nw + i] = f[i]; |
| else |
| for (i = a->top - 1; i >= 0; i--) { |
| l = f[i]; |
| t[nw + i + 1] |= (l >> rb) & BN_MASK2; |
| t[nw + i] = (l << lb) & BN_MASK2; |
| } |
| memset(t, 0, sizeof(*t) * nw); |
| r->top = a->top + nw + 1; |
| bn_correct_top(r); |
| bn_check_top(r); |
| return (1); |
| } |
| |
| int BN_rshift(BIGNUM *r, const BIGNUM *a, int n) |
| { |
| int i, j, nw, lb, rb; |
| BN_ULONG *t, *f; |
| BN_ULONG l, tmp; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| if (n < 0) { |
| BNerr(BN_F_BN_RSHIFT, BN_R_INVALID_SHIFT); |
| return 0; |
| } |
| |
| nw = n / BN_BITS2; |
| rb = n % BN_BITS2; |
| lb = BN_BITS2 - rb; |
| if (nw >= a->top || a->top == 0) { |
| BN_zero(r); |
| return (1); |
| } |
| i = (BN_num_bits(a) - n + (BN_BITS2 - 1)) / BN_BITS2; |
| if (r != a) { |
| if (bn_wexpand(r, i) == NULL) |
| return (0); |
| r->neg = a->neg; |
| } else { |
| if (n == 0) |
| return 1; /* or the copying loop will go berserk */ |
| } |
| |
| f = &(a->d[nw]); |
| t = r->d; |
| j = a->top - nw; |
| r->top = i; |
| |
| if (rb == 0) { |
| for (i = j; i != 0; i--) |
| *(t++) = *(f++); |
| } else { |
| l = *(f++); |
| for (i = j - 1; i != 0; i--) { |
| tmp = (l >> rb) & BN_MASK2; |
| l = *(f++); |
| *(t++) = (tmp | (l << lb)) & BN_MASK2; |
| } |
| if ((l = (l >> rb) & BN_MASK2)) |
| *(t) = l; |
| } |
| if (!r->top) |
| r->neg = 0; /* don't allow negative zero */ |
| bn_check_top(r); |
| return (1); |
| } |