ref: dc96f164a2b72ccb209ae98ce50a11087cbe44f8
dir: /sys/src/ape/lib/openssl/crypto/bn/bn_word.c/
/* crypto/bn/bn_word.c */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young ([email protected]).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson ([email protected]).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young ([email protected])"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson ([email protected])"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"
BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
{
#ifndef BN_LLONG
BN_ULONG ret=0;
#else
BN_ULLONG ret=0;
#endif
int i;
if (w == 0)
return (BN_ULONG)-1;
bn_check_top(a);
w&=BN_MASK2;
for (i=a->top-1; i>=0; i--)
{
#ifndef BN_LLONG
ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w;
ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w;
#else
ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
(BN_ULLONG)w);
#endif
}
return((BN_ULONG)ret);
}
BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
{
BN_ULONG ret = 0;
int i, j;
bn_check_top(a);
w &= BN_MASK2;
if (!w)
/* actually this an error (division by zero) */
return (BN_ULONG)-1;
if (a->top == 0)
return 0;
/* normalize input (so bn_div_words doesn't complain) */
j = BN_BITS2 - BN_num_bits_word(w);
w <<= j;
if (!BN_lshift(a, a, j))
return (BN_ULONG)-1;
for (i=a->top-1; i>=0; i--)
{
BN_ULONG l,d;
l=a->d[i];
d=bn_div_words(ret,l,w);
ret=(l-((d*w)&BN_MASK2))&BN_MASK2;
a->d[i]=d;
}
if ((a->top > 0) && (a->d[a->top-1] == 0))
a->top--;
ret >>= j;
bn_check_top(a);
return(ret);
}
int BN_add_word(BIGNUM *a, BN_ULONG w)
{
BN_ULONG l;
int i;
bn_check_top(a);
w &= BN_MASK2;
/* degenerate case: w is zero */
if (!w) return 1;
/* degenerate case: a is zero */
if(BN_is_zero(a)) return BN_set_word(a, w);
/* handle 'a' when negative */
if (a->neg)
{
a->neg=0;
i=BN_sub_word(a,w);
if (!BN_is_zero(a))
a->neg=!(a->neg);
return(i);
}
/* Only expand (and risk failing) if it's possibly necessary */
if (((BN_ULONG)(a->d[a->top - 1] + 1) == 0) &&
(bn_wexpand(a,a->top+1) == NULL))
return(0);
i=0;
for (;;)
{
if (i >= a->top)
l=w;
else
l=(a->d[i]+w)&BN_MASK2;
a->d[i]=l;
if (w > l)
w=1;
else
break;
i++;
}
if (i >= a->top)
a->top++;
bn_check_top(a);
return(1);
}
int BN_sub_word(BIGNUM *a, BN_ULONG w)
{
int i;
bn_check_top(a);
w &= BN_MASK2;
/* degenerate case: w is zero */
if (!w) return 1;
/* degenerate case: a is zero */
if(BN_is_zero(a))
{
i = BN_set_word(a,w);
if (i != 0)
BN_set_negative(a, 1);
return i;
}
/* handle 'a' when negative */
if (a->neg)
{
a->neg=0;
i=BN_add_word(a,w);
a->neg=1;
return(i);
}
if ((a->top == 1) && (a->d[0] < w))
{
a->d[0]=w-a->d[0];
a->neg=1;
return(1);
}
i=0;
for (;;)
{
if (a->d[i] >= w)
{
a->d[i]-=w;
break;
}
else
{
a->d[i]=(a->d[i]-w)&BN_MASK2;
i++;
w=1;
}
}
if ((a->d[i] == 0) && (i == (a->top-1)))
a->top--;
bn_check_top(a);
return(1);
}
int BN_mul_word(BIGNUM *a, BN_ULONG w)
{
BN_ULONG ll;
bn_check_top(a);
w&=BN_MASK2;
if (a->top)
{
if (w == 0)
BN_zero(a);
else
{
ll=bn_mul_words(a->d,a->d,a->top,w);
if (ll)
{
if (bn_wexpand(a,a->top+1) == NULL) return(0);
a->d[a->top++]=ll;
}
}
}
bn_check_top(a);
return(1);
}