diff options
Diffstat (limited to 'openssl/crypto/bn/bn_div.c')
| -rw-r--r-- | openssl/crypto/bn/bn_div.c | 755 |
1 files changed, 392 insertions, 363 deletions
diff --git a/openssl/crypto/bn/bn_div.c b/openssl/crypto/bn/bn_div.c index 7b2403185..72e6ce3f7 100644 --- a/openssl/crypto/bn/bn_div.c +++ b/openssl/crypto/bn/bn_div.c @@ -5,21 +5,21 @@ * 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: @@ -34,10 +34,10 @@ * 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 + * 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 @@ -49,7 +49,7 @@ * 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 @@ -61,77 +61,86 @@ #include "cryptlib.h" #include "bn_lcl.h" - /* 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)) - { - BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO); - 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); - if(bn_wexpand(dv,1) == NULL) goto end; - 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; - } + 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)) { + BNerr(BN_F_BN_DIV, BN_R_DIV_BY_ZERO); + 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); + if (bn_wexpand(dv, 1) == NULL) + goto end; + 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; + 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); - } + BN_CTX_end(ctx); + return (ret); +} #else -#if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \ +# if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \ && !defined(PEDANTIC) && !defined(BN_DIV3W) -# if defined(__GNUC__) && __GNUC__>=2 -# if defined(__i386) || defined (__i386__) - /* +# if defined(__GNUC__) && __GNUC__>=2 +# if defined(__i386) || 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 @@ -139,39 +148,39 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, * - divl doesn't only calculate quotient, but also leaves * remainder in %edx which we can definitely use here:-) * - * <appro@fy.chalmers.se> + * <appro@fy.chalmers.se> */ -#undef bn_div_words -# 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 -# elif defined(__x86_64) && defined(SIXTY_FOUR_BIT_LONG) +# undef bn_div_words +# 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 +# elif defined(__x86_64) && defined(SIXTY_FOUR_BIT_LONG) /* * Same story here, but it's 128-bit by 64-bit division. Wow! - * <appro@fy.chalmers.se> + * <appro@fy.chalmers.se> */ -# undef bn_div_words -# define bn_div_words(n0,n1,d0) \ - ({ asm volatile ( \ - "divq %4" \ - : "=a"(q), "=d"(rem) \ - : "a"(n1), "d"(n0), "g"(d0) \ - : "cc"); \ - q; \ - }) -# define REMAINDER_IS_ALREADY_CALCULATED -# endif /* __<cpu> */ -# endif /* __GNUC__ */ -#endif /* OPENSSL_NO_ASM */ - - -/* BN_div computes dv := num / divisor, rounding towards +# undef bn_div_words +# define bn_div_words(n0,n1,d0) \ + ({ asm volatile ( \ + "divq %4" \ + : "=a"(q), "=d"(rem) \ + : "a"(n1), "d"(n0), "g"(d0) \ + : "cc"); \ + q; \ + }) +# define REMAINDER_IS_ALREADY_CALCULATED +# endif /* __<cpu> */ +# endif /* __GNUC__ */ +# endif /* OPENSSL_NO_ASM */ + +/*- + * BN_div computes dv := num / divisor, rounding towards * zero, and sets up rm such that dv*divisor + rm = num holds. * Thus: * dv->neg == num->neg ^ divisor->neg (unless the result is zero) @@ -179,270 +188,290 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, * If 'dv' or 'rm' is NULL, the respective value is not returned. */ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, - BN_CTX *ctx) - { - int norm_shift,i,loop; - BIGNUM *tmp,wnum,*snum,*sdiv,*res; - BN_ULONG *resp,*wnump; - BN_ULONG d0,d1; - int num_n,div_n; - int no_branch=0; - - /* Invalid zero-padding would have particularly bad consequences - * in the case of 'num', so don't just rely on bn_check_top() for this one - * (bn_check_top() works only for BN_DEBUG builds) */ - if (num->top > 0 && num->d[num->top - 1] == 0) - { - BNerr(BN_F_BN_DIV,BN_R_NOT_INITIALIZED); - return 0; - } - - bn_check_top(num); - - if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0)) - { - no_branch=1; - } - - bn_check_top(dv); - bn_check_top(rm); - /* bn_check_top(num); */ /* 'num' has been checked already */ - bn_check_top(divisor); - - if (BN_is_zero(divisor)) - { - BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO); - return(0); - } - - if (!no_branch && 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); - snum=BN_CTX_get(ctx); - sdiv=BN_CTX_get(ctx); - if (dv == NULL) - res=BN_CTX_get(ctx); - else res=dv; - if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL) - goto err; - - /* First we normalise the numbers */ - norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2); - if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err; - sdiv->neg=0; - norm_shift+=BN_BITS2; - if (!(BN_lshift(snum,num,norm_shift))) goto err; - snum->neg=0; - - if (no_branch) - { - /* Since we don't know whether snum is larger than sdiv, - * we pad snum with enough zeroes without changing its - * value. - */ - if (snum->top <= sdiv->top+1) - { - if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err; - for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0; - snum->top = sdiv->top + 2; - } - else - { - if (bn_wexpand(snum, snum->top + 1) == NULL) goto err; - snum->d[snum->top] = 0; - snum->top ++; - } - } - - 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 */ - wnum.neg = 0; - wnum.d = &(snum->d[loop]); - wnum.top = div_n; - /* only needed when BN_ucmp messes up the values between top and max */ - wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */ - - /* Get the top 2 words of sdiv */ - /* div_n=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-no_branch; - resp= &(res->d[loop-1]); - - /* space for temp */ - if (!bn_wexpand(tmp,(div_n+1))) goto err; - - if (!no_branch) - { - if (BN_ucmp(&wnum,sdiv) >= 0) - { - /* If BN_DEBUG_RAND is defined BN_ucmp changes (via - * bn_pollute) the const bignum arguments => - * clean the values between top and max again */ - bn_clear_top2max(&wnum); - bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n); - *resp=1; - } - else - res->top--; - } - - /* if res->top == 0 then clear the neg value otherwise decrease - * the resp pointer */ - if (res->top == 0) - res->neg = 0; - else - resp--; - - for (i=0; i<loop-1; i++, wnump--, resp--) - { - BN_ULONG q,l0; - /* the first part of the loop uses the top two words of - * snum and sdiv to calculate a BN_ULONG q such that - * | wnum - sdiv * q | < sdiv */ -#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM) - BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG); - 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); -#ifdef BN_DEBUG_LEVITTE - fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\ -X) -> 0x%08X\n", - n0, n1, d0, q); -#endif -#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; - - q=bn_div_words(n0,n1,d0); -#ifdef BN_DEBUG_LEVITTE - fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\ -X) -> 0x%08X\n", - n0, n1, d0, q); -#endif -#ifndef REMAINDER_IS_ALREADY_CALCULATED - rem=(n1-q*d0)&BN_MASK2; -#endif - -#if defined(BN_UMULT_LOHI) - BN_UMULT_LOHI(t2l,t2h,d1,q); -#elif defined(BN_UMULT_HIGH) - t2l = d1 * q; - t2h = BN_UMULT_HIGH(d1,q); -#else - { - BN_ULONG ql, qh; - 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); - tmp->d[div_n]=l0; - wnum.d--; - /* ingore top values of the bignums just sub the two - * BN_ULONG arrays with bn_sub_words */ - if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1)) - { - /* Note: As we have considered only the leading - * two BN_ULONGs in the calculation of q, sdiv * q - * might be greater than wnum (but then (q-1) * sdiv - * is less or equal than wnum) - */ - q--; - if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n)) - /* we can't have an overflow here (assuming - * that q != 0, but if q == 0 then tmp is - * zero anyway) */ - (*wnump)++; - } - /* store part of the result */ - *resp = q; - } - bn_correct_top(snum); - if (rm != NULL) - { - /* Keep a copy of the neg flag in num because if rm==num - * BN_rshift() will overwrite it. - */ - int neg = num->neg; - BN_rshift(rm,snum,norm_shift); - if (!BN_is_zero(rm)) - rm->neg = neg; - bn_check_top(rm); - } - if (no_branch) bn_correct_top(res); - BN_CTX_end(ctx); - return(1); -err: - bn_check_top(rm); - BN_CTX_end(ctx); - return(0); - } + BN_CTX *ctx) +{ + int norm_shift, i, loop; + BIGNUM *tmp, wnum, *snum, *sdiv, *res; + BN_ULONG *resp, *wnump; + BN_ULONG d0, d1; + int num_n, div_n; + int no_branch = 0; + + /* + * Invalid zero-padding would have particularly bad consequences so don't + * just rely on bn_check_top() here (bn_check_top() works only for + * BN_DEBUG builds) + */ + if ((num->top > 0 && num->d[num->top - 1] == 0) || + (divisor->top > 0 && divisor->d[divisor->top - 1] == 0)) { + BNerr(BN_F_BN_DIV, BN_R_NOT_INITIALIZED); + return 0; + } + + bn_check_top(num); + bn_check_top(divisor); + + if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) + || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0)) { + no_branch = 1; + } + + bn_check_top(dv); + bn_check_top(rm); + /*- bn_check_top(num); *//* + * 'num' has been checked already + */ + /*- bn_check_top(divisor); *//* + * 'divisor' has been checked already + */ + + if (BN_is_zero(divisor)) { + BNerr(BN_F_BN_DIV, BN_R_DIV_BY_ZERO); + return (0); + } + + if (!no_branch && 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); + snum = BN_CTX_get(ctx); + sdiv = BN_CTX_get(ctx); + if (dv == NULL) + res = BN_CTX_get(ctx); + else + res = dv; + if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL) + goto err; + + /* First we normalise the numbers */ + norm_shift = BN_BITS2 - ((BN_num_bits(divisor)) % BN_BITS2); + if (!(BN_lshift(sdiv, divisor, norm_shift))) + goto err; + sdiv->neg = 0; + norm_shift += BN_BITS2; + if (!(BN_lshift(snum, num, norm_shift))) + goto err; + snum->neg = 0; + + if (no_branch) { + /* + * Since we don't know whether snum is larger than sdiv, we pad snum + * with enough zeroes without changing its value. + */ + if (snum->top <= sdiv->top + 1) { + if (bn_wexpand(snum, sdiv->top + 2) == NULL) + goto err; + for (i = snum->top; i < sdiv->top + 2; i++) + snum->d[i] = 0; + snum->top = sdiv->top + 2; + } else { + if (bn_wexpand(snum, snum->top + 1) == NULL) + goto err; + snum->d[snum->top] = 0; + snum->top++; + } + } + + 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 + */ + wnum.neg = 0; + wnum.d = &(snum->d[loop]); + wnum.top = div_n; + /* + * only needed when BN_ucmp messes up the values between top and max + */ + wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */ + + /* Get the top 2 words of sdiv */ + /* div_n=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 - no_branch; + resp = &(res->d[loop - 1]); + + /* space for temp */ + if (!bn_wexpand(tmp, (div_n + 1))) + goto err; + + if (!no_branch) { + if (BN_ucmp(&wnum, sdiv) >= 0) { + /* + * If BN_DEBUG_RAND is defined BN_ucmp changes (via bn_pollute) + * the const bignum arguments => clean the values between top and + * max again + */ + bn_clear_top2max(&wnum); + bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n); + *resp = 1; + } else + res->top--; + } + + /* + * if res->top == 0 then clear the neg value otherwise decrease the resp + * pointer + */ + if (res->top == 0) + res->neg = 0; + else + resp--; + + for (i = 0; i < loop - 1; i++, wnump--, resp--) { + BN_ULONG q, l0; + /* + * the first part of the loop uses the top two words of snum and sdiv + * to calculate a BN_ULONG q such that | wnum - sdiv * q | < sdiv + */ +# if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM) + BN_ULONG bn_div_3_words(BN_ULONG *, BN_ULONG, BN_ULONG); + 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); +# ifdef BN_DEBUG_LEVITTE + fprintf(stderr, "DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\ +X) -> 0x%08X\n", n0, n1, d0, q); +# endif +# 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; + + q = bn_div_words(n0, n1, d0); +# ifdef BN_DEBUG_LEVITTE + fprintf(stderr, "DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\ +X) -> 0x%08X\n", n0, n1, d0, q); +# endif +# ifndef REMAINDER_IS_ALREADY_CALCULATED + rem = (n1 - q * d0) & BN_MASK2; +# endif + +# if defined(BN_UMULT_LOHI) + BN_UMULT_LOHI(t2l, t2h, d1, q); +# elif defined(BN_UMULT_HIGH) + t2l = d1 * q; + t2h = BN_UMULT_HIGH(d1, q); +# else + { + BN_ULONG ql, qh; + 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); + tmp->d[div_n] = l0; + wnum.d--; + /* + * ingore top values of the bignums just sub the two BN_ULONG arrays + * with bn_sub_words + */ + if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n + 1)) { + /* + * Note: As we have considered only the leading two BN_ULONGs in + * the calculation of q, sdiv * q might be greater than wnum (but + * then (q-1) * sdiv is less or equal than wnum) + */ + q--; + if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n)) + /* + * we can't have an overflow here (assuming that q != 0, but + * if q == 0 then tmp is zero anyway) + */ + (*wnump)++; + } + /* store part of the result */ + *resp = q; + } + bn_correct_top(snum); + if (rm != NULL) { + /* + * Keep a copy of the neg flag in num because if rm==num BN_rshift() + * will overwrite it. + */ + int neg = num->neg; + BN_rshift(rm, snum, norm_shift); + if (!BN_is_zero(rm)) + rm->neg = neg; + bn_check_top(rm); + } + if (no_branch) + bn_correct_top(res); + BN_CTX_end(ctx); + return (1); + err: + bn_check_top(rm); + BN_CTX_end(ctx); + return (0); +} #endif |