+++ /dev/null
-/* crypto/bn/bn_div.c */
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
- *
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * 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 (tjh@cryptsoft.com).
- *
- * 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 (eay@cryptsoft.com)"
- * 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 (tjh@cryptsoft.com)"
- *
- * 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 "bn_lcl.h"
-
-#define NO_ASM
-
-/* The old slow way */
-#if 0
-int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
- BN_CTX *ctx)
- {
- int i,nm,nd;
- int ret = 0;
- BIGNUM *D;
-
- bn_check_top(m);
- bn_check_top(d);
- if (BN_is_zero(d))
- {
- return(0);
- }
-
- if (BN_ucmp(m,d) < 0)
- {
- if (rem != NULL)
- { if (BN_copy(rem,m) == NULL) return(0); }
- if (dv != NULL) BN_zero(dv);
- return(1);
- }
-
- BN_CTX_start(ctx);
- D = BN_CTX_get(ctx);
- if (dv == NULL) dv = BN_CTX_get(ctx);
- if (rem == NULL) rem = BN_CTX_get(ctx);
- if (D == NULL || dv == NULL || rem == NULL)
- goto end;
-
- nd=BN_num_bits(d);
- nm=BN_num_bits(m);
- if (BN_copy(D,d) == NULL) goto end;
- if (BN_copy(rem,m) == NULL) goto end;
-
- /* The next 2 are needed so we can do a dv->d[0]|=1 later
- * since BN_lshift1 will only work once there is a value :-) */
- BN_zero(dv);
- bn_wexpand(dv,1);
- dv->top=1;
-
- if (!BN_lshift(D,D,nm-nd)) goto end;
- for (i=nm-nd; i>=0; i--)
- {
- if (!BN_lshift1(dv,dv)) goto end;
- if (BN_ucmp(rem,D) >= 0)
- {
- dv->d[0]|=1;
- if (!BN_usub(rem,rem,D)) goto end;
- }
-/* CAN IMPROVE (and have now :=) */
- if (!BN_rshift1(D,D)) goto end;
- }
- rem->neg=BN_is_zero(rem)?0:m->neg;
- dv->neg=m->neg^d->neg;
- ret = 1;
- end:
- BN_CTX_end(ctx);
- return(ret);
- }
-
-#else
-
-#if !defined(NO_ASM) && !defined(NO_INLINE_ASM) && !defined(PEDANTIC) && !defined(BN_DIV3W)
-# if defined(__GNUC__) && __GNUC__>=2
-# if defined(__i386)
- /*
- * There were two reasons for implementing this template:
- * - GNU C generates a call to a function (__udivdi3 to be exact)
- * in reply to ((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0 (I fail to
- * understand why...);
- * - divl doesn't only calculate quotient, but also leaves
- * remainder in %edx which we can definitely use here:-)
- *
- * <appro@fy.chalmers.se>
- */
-# define bn_div_words(n0,n1,d0) \
- ({ asm volatile ( \
- "divl %4" \
- : "=a"(q), "=d"(rem) \
- : "a"(n1), "d"(n0), "g"(d0) \
- : "cc"); \
- q; \
- })
-# define REMAINDER_IS_ALREADY_CALCULATED
-# endif /* __<cpu> */
-# endif /* __GNUC__ */
-#endif /* NO_ASM */
-
-int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
- BN_CTX *ctx)
- {
- int norm_shift,i,j,loop;
- BIGNUM *tmp,wnum,*snum,*sdiv,*res;
- BN_ULONG *resp,*wnump;
- BN_ULONG d0,d1;
- int num_n,div_n;
-
- bn_check_top(num);
- bn_check_top(divisor);
-
- if (BN_is_zero(divisor))
- {
- return(0);
- }
-
- if (BN_ucmp(num,divisor) < 0)
- {
- if (rm != NULL)
- { if (BN_copy(rm,num) == NULL) return(0); }
- if (dv != NULL) BN_zero(dv);
- return(1);
- }
-
- BN_CTX_start(ctx);
- tmp=BN_CTX_get(ctx);
- tmp->neg=0;
- snum=BN_CTX_get(ctx);
- sdiv=BN_CTX_get(ctx);
- if (dv == NULL)
- res=BN_CTX_get(ctx);
- else res=dv;
- if (res == NULL) goto err;
-
- /* First we normalise the numbers */
- norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
- BN_lshift(sdiv,divisor,norm_shift);
- sdiv->neg=0;
- norm_shift+=BN_BITS2;
- BN_lshift(snum,num,norm_shift);
- snum->neg=0;
- div_n=sdiv->top;
- num_n=snum->top;
- loop=num_n-div_n;
-
- /* Lets setup a 'window' into snum
- * This is the part that corresponds to the current
- * 'area' being divided */
- BN_init(&wnum);
- wnum.d= &(snum->d[loop]);
- wnum.top= div_n;
- wnum.dmax= snum->dmax+1; /* a bit of a lie */
-
- /* Get the top 2 words of sdiv */
- /* i=sdiv->top; */
- d0=sdiv->d[div_n-1];
- d1=(div_n == 1)?0:sdiv->d[div_n-2];
-
- /* pointer to the 'top' of snum */
- wnump= &(snum->d[num_n-1]);
-
- /* Setup to 'res' */
- res->neg= (num->neg^divisor->neg);
- if (!bn_wexpand(res,(loop+1))) goto err;
- res->top=loop;
- resp= &(res->d[loop-1]);
-
- /* space for temp */
- if (!bn_wexpand(tmp,(div_n+1))) goto err;
-
- if (BN_ucmp(&wnum,sdiv) >= 0)
- {
- if (!BN_usub(&wnum,&wnum,sdiv)) goto err;
- *resp=1;
- res->d[res->top-1]=1;
- }
- else
- res->top--;
- resp--;
-
- for (i=0; i<loop-1; i++)
- {
- BN_ULONG q,l0;
-#ifdef BN_DIV3W
- q=bn_div_3_words(wnump,d1,d0);
-#else
- BN_ULONG n0,n1,rem=0;
-
- n0=wnump[0];
- n1=wnump[-1];
- if (n0 == d0)
- q=BN_MASK2;
- else /* n0 < d0 */
- {
-#ifdef BN_LLONG
- BN_ULLONG t2;
-
-#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
- q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
-#else
- q=bn_div_words(n0,n1,d0);
-#endif
-
-#ifndef REMAINDER_IS_ALREADY_CALCULATED
- /*
- * rem doesn't have to be BN_ULLONG. The least we
- * know it's less that d0, isn't it?
- */
- rem=(n1-q*d0)&BN_MASK2;
-#endif
- t2=(BN_ULLONG)d1*q;
-
- for (;;)
- {
- if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)|wnump[-2]))
- break;
- q--;
- rem += d0;
- if (rem < d0) break; /* don't let rem overflow */
- t2 -= d1;
- }
-#else /* !BN_LLONG */
- BN_ULONG t2l,t2h,ql,qh;
-
- q=bn_div_words(n0,n1,d0);
-#ifndef REMAINDER_IS_ALREADY_CALCULATED
- rem=(n1-q*d0)&BN_MASK2;
-#endif
-
-#ifdef BN_UMULT_HIGH
- t2l = d1 * q;
- t2h = BN_UMULT_HIGH(d1,q);
-#else
- t2l=LBITS(d1); t2h=HBITS(d1);
- ql =LBITS(q); qh =HBITS(q);
- mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
-#endif
-
- for (;;)
- {
- if ((t2h < rem) ||
- ((t2h == rem) && (t2l <= wnump[-2])))
- break;
- q--;
- rem += d0;
- if (rem < d0) break; /* don't let rem overflow */
- if (t2l < d1) t2h--; t2l -= d1;
- }
-#endif /* !BN_LLONG */
- }
-#endif /* !BN_DIV3W */
-
- l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
- wnum.d--; wnum.top++;
- tmp->d[div_n]=l0;
- for (j=div_n+1; j>0; j--)
- if (tmp->d[j-1]) break;
- tmp->top=j;
-
- j=wnum.top;
- BN_sub(&wnum,&wnum,tmp);
-
- snum->top=snum->top+wnum.top-j;
-
- if (wnum.neg)
- {
- q--;
- j=wnum.top;
- BN_add(&wnum,&wnum,sdiv);
- snum->top+=wnum.top-j;
- }
- *(resp--)=q;
- wnump--;
- }
- if (rm != NULL)
- {
- BN_rshift(rm,snum,norm_shift);
- rm->neg=num->neg;
- }
- BN_CTX_end(ctx);
- return(1);
-err:
- BN_CTX_end(ctx);
- return(0);
- }
-
-#endif
-
-/* rem != m */
-int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
- {
-#if 0 /* The old slow way */
- int i,nm,nd;
- BIGNUM *dv;
-
- if (BN_ucmp(m,d) < 0)
- return((BN_copy(rem,m) == NULL)?0:1);
-
- BN_CTX_start(ctx);
- dv=BN_CTX_get(ctx);
-
- if (!BN_copy(rem,m)) goto err;
-
- nm=BN_num_bits(rem);
- nd=BN_num_bits(d);
- if (!BN_lshift(dv,d,nm-nd)) goto err;
- for (i=nm-nd; i>=0; i--)
- {
- if (BN_cmp(rem,dv) >= 0)
- {
- if (!BN_sub(rem,rem,dv)) goto err;
- }
- if (!BN_rshift1(dv,dv)) goto err;
- }
- BN_CTX_end(ctx);
- return(1);
- err:
- BN_CTX_end(ctx);
- return(0);
-#else
- return(BN_div(NULL,rem,m,d,ctx));
-#endif
- }
-
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