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boringssl / boringssl.git / d94682dce5263e11bacd47e8d33e77c0315eac5c / . / crypto / fipsmodule / bn / mul.c
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/* 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 <openssl/bn.h>
#include <assert.h>
#include <string.h>
#include "internal.h"
#define BN_MUL_RECURSIVE_SIZE_NORMAL 16
#define BN_SQR_RECURSIVE_SIZE_NORMAL BN_MUL_RECURSIVE_SIZE_NORMAL
static void bn_mul_normal(BN_ULONG *r, BN_ULONG *a, int na, BN_ULONG *b,
int nb) {
BN_ULONG *rr;
if (na < nb) {
int itmp;
BN_ULONG *ltmp;
itmp = na;
na = nb;
nb = itmp;
ltmp = a;
a = b;
b = ltmp;
}
rr = &(r[na]);
if (nb <= 0) {
(void)bn_mul_words(r, a, na, 0);
return;
} else {
rr[0] = bn_mul_words(r, a, na, b[0]);
}
for (;;) {
if (--nb <= 0) {
return;
}
rr[1] = bn_mul_add_words(&(r[1]), a, na, b[1]);
if (--nb <= 0) {
return;
}
rr[2] = bn_mul_add_words(&(r[2]), a, na, b[2]);
if (--nb <= 0) {
return;
}
rr[3] = bn_mul_add_words(&(r[3]), a, na, b[3]);
if (--nb <= 0) {
return;
}
rr[4] = bn_mul_add_words(&(r[4]), a, na, b[4]);
rr += 4;
r += 4;
b += 4;
}
}
#if !defined(OPENSSL_X86) || defined(OPENSSL_NO_ASM)
/* Here follows specialised variants of bn_add_words() and bn_sub_words(). They
* have the property performing operations on arrays of different sizes. The
* sizes of those arrays is expressed through cl, which is the common length (
* basicall, min(len(a),len(b)) ), and dl, which is the delta between the two
* lengths, calculated as len(a)-len(b). All lengths are the number of
* BN_ULONGs... For the operations that require a result array as parameter,
* it must have the length cl+abs(dl). These functions should probably end up
* in bn_asm.c as soon as there are assembler counterparts for the systems that
* use assembler files. */
static BN_ULONG bn_sub_part_words(BN_ULONG *r, const BN_ULONG *a,
const BN_ULONG *b, int cl, int dl) {
BN_ULONG c, t;
assert(cl >= 0);
c = bn_sub_words(r, a, b, cl);
if (dl == 0) {
return c;
}
r += cl;
a += cl;
b += cl;
if (dl < 0) {
for (;;) {
t = b[0];
r[0] = (0 - t - c) & BN_MASK2;
if (t != 0) {
c = 1;
}
if (++dl >= 0) {
break;
}
t = b[1];
r[1] = (0 - t - c) & BN_MASK2;
if (t != 0) {
c = 1;
}
if (++dl >= 0) {
break;
}
t = b[2];
r[2] = (0 - t - c) & BN_MASK2;
if (t != 0) {
c = 1;
}
if (++dl >= 0) {
break;
}
t = b[3];
r[3] = (0 - t - c) & BN_MASK2;
if (t != 0) {
c = 1;
}
if (++dl >= 0) {
break;
}
b += 4;
r += 4;
}
} else {
int save_dl = dl;
while (c) {
t = a[0];
r[0] = (t - c) & BN_MASK2;
if (t != 0) {
c = 0;
}
if (--dl <= 0) {
break;
}
t = a[1];
r[1] = (t - c) & BN_MASK2;
if (t != 0) {
c = 0;
}
if (--dl <= 0) {
break;
}
t = a[2];
r[2] = (t - c) & BN_MASK2;
if (t != 0) {
c = 0;
}
if (--dl <= 0) {
break;
}
t = a[3];
r[3] = (t - c) & BN_MASK2;
if (t != 0) {
c = 0;
}
if (--dl <= 0) {
break;
}
save_dl = dl;
a += 4;
r += 4;
}
if (dl > 0) {
if (save_dl > dl) {
switch (save_dl - dl) {
case 1:
r[1] = a[1];
if (--dl <= 0) {
break;
}
case 2:
r[2] = a[2];
if (--dl <= 0) {
break;
}
case 3:
r[3] = a[3];
if (--dl <= 0) {
break;
}
}
a += 4;
r += 4;
}
}
if (dl > 0) {
for (;;) {
r[0] = a[0];
if (--dl <= 0) {
break;
}
r[1] = a[1];
if (--dl <= 0) {
break;
}
r[2] = a[2];
if (--dl <= 0) {
break;
}
r[3] = a[3];
if (--dl <= 0) {
break;
}
a += 4;
r += 4;
}
}
}
return c;
}
#else
/* On other platforms the function is defined in asm. */
BN_ULONG bn_sub_part_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b,
int cl, int dl);
#endif
/* Karatsuba recursive multiplication algorithm
* (cf. Knuth, The Art of Computer Programming, Vol. 2) */
/* r is 2*n2 words in size,
* a and b are both n2 words in size.
* n2 must be a power of 2.
* We multiply and return the result.
* t must be 2*n2 words in size
* We calculate
* a[0]*b[0]
* a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
* a[1]*b[1]
*/
/* dnX may not be positive, but n2/2+dnX has to be */
static void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
int dna, int dnb, BN_ULONG *t) {
int n = n2 / 2, c1, c2;
int tna = n + dna, tnb = n + dnb;
unsigned int neg, zero;
BN_ULONG ln, lo, *p;
/* Only call bn_mul_comba 8 if n2 == 8 and the
* two arrays are complete [steve]
*/
if (n2 == 8 && dna == 0 && dnb == 0) {
bn_mul_comba8(r, a, b);
return;
}
/* Else do normal multiply */
if (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL) {
bn_mul_normal(r, a, n2 + dna, b, n2 + dnb);
if ((dna + dnb) < 0) {
OPENSSL_memset(&r[2 * n2 + dna + dnb], 0,
sizeof(BN_ULONG) * -(dna + dnb));
}
return;
}
/* r=(a[0]-a[1])*(b[1]-b[0]) */
c1 = bn_cmp_part_words(a, &(a[n]), tna, n - tna);
c2 = bn_cmp_part_words(&(b[n]), b, tnb, tnb - n);
zero = neg = 0;
switch (c1 * 3 + c2) {
case -4:
bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
break;
case -3:
zero = 1;
break;
case -2:
bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n); /* + */
neg = 1;
break;
case -1:
case 0:
case 1:
zero = 1;
break;
case 2:
bn_sub_part_words(t, a, &(a[n]), tna, n - tna); /* + */
bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
neg = 1;
break;
case 3:
zero = 1;
break;
case 4:
bn_sub_part_words(t, a, &(a[n]), tna, n - tna);
bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n);
break;
}
if (n == 4 && dna == 0 && dnb == 0) {
/* XXX: bn_mul_comba4 could take extra args to do this well */
if (!zero) {
bn_mul_comba4(&(t[n2]), t, &(t[n]));
} else {
OPENSSL_memset(&(t[n2]), 0, 8 * sizeof(BN_ULONG));
}
bn_mul_comba4(r, a, b);
bn_mul_comba4(&(r[n2]), &(a[n]), &(b[n]));
} else if (n == 8 && dna == 0 && dnb == 0) {
/* XXX: bn_mul_comba8 could take extra args to do this well */
if (!zero) {
bn_mul_comba8(&(t[n2]), t, &(t[n]));
} else {
OPENSSL_memset(&(t[n2]), 0, 16 * sizeof(BN_ULONG));
}
bn_mul_comba8(r, a, b);
bn_mul_comba8(&(r[n2]), &(a[n]), &(b[n]));
} else {
p = &(t[n2 * 2]);
if (!zero) {
bn_mul_recursive(&(t[n2]), t, &(t[n]), n, 0, 0, p);
} else {
OPENSSL_memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
}
bn_mul_recursive(r, a, b, n, 0, 0, p);
bn_mul_recursive(&(r[n2]), &(a[n]), &(b[n]), n, dna, dnb, p);
}
/* t[32] holds (a[0]-a[1])*(b[1]-b[0]), c1 is the sign
* r[10] holds (a[0]*b[0])
* r[32] holds (b[1]*b[1]) */
c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
if (neg) {
/* if t[32] is negative */
c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
} else {
/* Might have a carry */
c1 += (int)(bn_add_words(&(t[n2]), &(t[n2]), t, n2));
}
/* t[32] holds (a[0]-a[1])*(b[1]-b[0])+(a[0]*b[0])+(a[1]*b[1])
* r[10] holds (a[0]*b[0])
* r[32] holds (b[1]*b[1])
* c1 holds the carry bits */
c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
if (c1) {
p = &(r[n + n2]);
lo = *p;
ln = (lo + c1) & BN_MASK2;
*p = ln;
/* The overflow will stop before we over write
* words we should not overwrite */
if (ln < (BN_ULONG)c1) {
do {
p++;
lo = *p;
ln = (lo + 1) & BN_MASK2;
*p = ln;
} while (ln == 0);
}
}
}
/* n+tn is the word length
* t needs to be n*4 is size, as does r */
/* tnX may not be negative but less than n */
static void bn_mul_part_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n,
int tna, int tnb, BN_ULONG *t) {
int i, j, n2 = n * 2;
int c1, c2, neg;
BN_ULONG ln, lo, *p;
if (n < 8) {
bn_mul_normal(r, a, n + tna, b, n + tnb);
return;
}
/* r=(a[0]-a[1])*(b[1]-b[0]) */
c1 = bn_cmp_part_words(a, &(a[n]), tna, n - tna);
c2 = bn_cmp_part_words(&(b[n]), b, tnb, tnb - n);
neg = 0;
switch (c1 * 3 + c2) {
case -4:
bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
break;
case -3:
/* break; */
case -2:
bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n); /* + */
neg = 1;
break;
case -1:
case 0:
case 1:
/* break; */
case 2:
bn_sub_part_words(t, a, &(a[n]), tna, n - tna); /* + */
bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
neg = 1;
break;
case 3:
/* break; */
case 4:
bn_sub_part_words(t, a, &(a[n]), tna, n - tna);
bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n);
break;
}
if (n == 8) {
bn_mul_comba8(&(t[n2]), t, &(t[n]));
bn_mul_comba8(r, a, b);
bn_mul_normal(&(r[n2]), &(a[n]), tna, &(b[n]), tnb);
OPENSSL_memset(&(r[n2 + tna + tnb]), 0, sizeof(BN_ULONG) * (n2 - tna - tnb));
} else {
p = &(t[n2 * 2]);
bn_mul_recursive(&(t[n2]), t, &(t[n]), n, 0, 0, p);
bn_mul_recursive(r, a, b, n, 0, 0, p);
i = n / 2;
/* If there is only a bottom half to the number,
* just do it */
if (tna > tnb) {
j = tna - i;
} else {
j = tnb - i;
}
if (j == 0) {
bn_mul_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i, tnb - i, p);
OPENSSL_memset(&(r[n2 + i * 2]), 0, sizeof(BN_ULONG) * (n2 - i * 2));
} else if (j > 0) {
/* eg, n == 16, i == 8 and tn == 11 */
bn_mul_part_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i, tnb - i, p);
OPENSSL_memset(&(r[n2 + tna + tnb]), 0,
sizeof(BN_ULONG) * (n2 - tna - tnb));
} else {
/* (j < 0) eg, n == 16, i == 8 and tn == 5 */
OPENSSL_memset(&(r[n2]), 0, sizeof(BN_ULONG) * n2);
if (tna < BN_MUL_RECURSIVE_SIZE_NORMAL &&
tnb < BN_MUL_RECURSIVE_SIZE_NORMAL) {
bn_mul_normal(&(r[n2]), &(a[n]), tna, &(b[n]), tnb);
} else {
for (;;) {
i /= 2;
/* these simplified conditions work
* exclusively because difference
* between tna and tnb is 1 or 0 */
if (i < tna || i < tnb) {
bn_mul_part_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i,
tnb - i, p);
break;
} else if (i == tna || i == tnb) {
bn_mul_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i, tnb - i,
p);
break;
}
}
}
}
}
/* t[32] holds (a[0]-a[1])*(b[1]-b[0]), c1 is the sign
* r[10] holds (a[0]*b[0])
* r[32] holds (b[1]*b[1])
*/
c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
if (neg) {
/* if t[32] is negative */
c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
} else {
/* Might have a carry */
c1 += (int)(bn_add_words(&(t[n2]), &(t[n2]), t, n2));
}
/* t[32] holds (a[0]-a[1])*(b[1]-b[0])+(a[0]*b[0])+(a[1]*b[1])
* r[10] holds (a[0]*b[0])
* r[32] holds (b[1]*b[1])
* c1 holds the carry bits */
c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
if (c1) {
p = &(r[n + n2]);
lo = *p;
ln = (lo + c1) & BN_MASK2;
*p = ln;
/* The overflow will stop before we over write
* words we should not overwrite */
if (ln < (BN_ULONG)c1) {
do {
p++;
lo = *p;
ln = (lo + 1) & BN_MASK2;
*p = ln;
} while (ln == 0);
}
}
}
int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx) {
int ret = 0;
int top, al, bl;
BIGNUM *rr;
int i;
BIGNUM *t = NULL;
int j = 0, k;
al = a->top;
bl = b->top;
if ((al == 0) || (bl == 0)) {
BN_zero(r);
return 1;
}
top = al + bl;
BN_CTX_start(ctx);
if ((r == a) || (r == b)) {
if ((rr = BN_CTX_get(ctx)) == NULL) {
goto err;
}
} else {
rr = r;
}
rr->neg = a->neg ^ b->neg;
i = al - bl;
if (i == 0) {
if (al == 8) {
if (!bn_wexpand(rr, 16)) {
goto err;
}
rr->top = 16;
bn_mul_comba8(rr->d, a->d, b->d);
goto end;
}
}
static const int kMulNormalSize = 16;
if (al >= kMulNormalSize && bl >= kMulNormalSize) {
if (i >= -1 && i <= 1) {
/* Find out the power of two lower or equal
to the longest of the two numbers */
if (i >= 0) {
j = BN_num_bits_word((BN_ULONG)al);
}
if (i == -1) {
j = BN_num_bits_word((BN_ULONG)bl);
}
j = 1 << (j - 1);
assert(j <= al || j <= bl);
k = j + j;
t = BN_CTX_get(ctx);
if (t == NULL) {
goto err;
}
if (al > j || bl > j) {
if (!bn_wexpand(t, k * 4)) {
goto err;
}
if (!bn_wexpand(rr, k * 4)) {
goto err;
}
bn_mul_part_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
} else {
/* al <= j || bl <= j */
if (!bn_wexpand(t, k * 2)) {
goto err;
}
if (!bn_wexpand(rr, k * 2)) {
goto err;
}
bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
}
rr->top = top;
goto end;
}
}
if (!bn_wexpand(rr, top)) {
goto err;
}
rr->top = top;
bn_mul_normal(rr->d, a->d, al, b->d, bl);
end:
bn_correct_top(rr);
if (r != rr && !BN_copy(r, rr)) {
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
/* tmp must have 2*n words */
static void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp) {
int i, j, max;
const BN_ULONG *ap;
BN_ULONG *rp;
max = n * 2;
ap = a;
rp = r;
rp[0] = rp[max - 1] = 0;
rp++;
j = n;
if (--j > 0) {
ap++;
rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
rp += 2;
}
for (i = n - 2; i > 0; i--) {
j--;
ap++;
rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
rp += 2;
}
bn_add_words(r, r, r, max);
/* There will not be a carry */
bn_sqr_words(tmp, a, n);
bn_add_words(r, r, tmp, max);
}
/* r is 2*n words in size,
* a and b are both n words in size. (There's not actually a 'b' here ...)
* n must be a power of 2.
* We multiply and return the result.
* t must be 2*n words in size
* We calculate
* a[0]*b[0]
* a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
* a[1]*b[1]
*/
static void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t) {
int n = n2 / 2;
int zero, c1;
BN_ULONG ln, lo, *p;
if (n2 == 4) {
bn_sqr_comba4(r, a);
return;
} else if (n2 == 8) {
bn_sqr_comba8(r, a);
return;
}
if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
bn_sqr_normal(r, a, n2, t);
return;
}
/* r=(a[0]-a[1])*(a[1]-a[0]) */
c1 = bn_cmp_words(a, &(a[n]), n);
zero = 0;
if (c1 > 0) {
bn_sub_words(t, a, &(a[n]), n);
} else if (c1 < 0) {
bn_sub_words(t, &(a[n]), a, n);
} else {
zero = 1;
}
/* The result will always be negative unless it is zero */
p = &(t[n2 * 2]);
if (!zero) {
bn_sqr_recursive(&(t[n2]), t, n, p);
} else {
OPENSSL_memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
}
bn_sqr_recursive(r, a, n, p);
bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
/* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
* r[10] holds (a[0]*b[0])
* r[32] holds (b[1]*b[1]) */
c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
/* t[32] is negative */
c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
/* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
* r[10] holds (a[0]*a[0])
* r[32] holds (a[1]*a[1])
* c1 holds the carry bits */
c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
if (c1) {
p = &(r[n + n2]);
lo = *p;
ln = (lo + c1) & BN_MASK2;
*p = ln;
/* The overflow will stop before we over write
* words we should not overwrite */
if (ln < (BN_ULONG)c1) {
do {
p++;
lo = *p;
ln = (lo + 1) & BN_MASK2;
*p = ln;
} while (ln == 0);
}
}
}
int BN_mul_word(BIGNUM *bn, BN_ULONG w) {
BN_ULONG ll;
w &= BN_MASK2;
if (!bn->top) {
return 1;
}
if (w == 0) {
BN_zero(bn);
return 1;
}
ll = bn_mul_words(bn->d, bn->d, bn->top, w);
if (ll) {
if (!bn_wexpand(bn, bn->top + 1)) {
return 0;
}
bn->d[bn->top++] = ll;
}
return 1;
}
int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx) {
int max, al;
int ret = 0;
BIGNUM *tmp, *rr;
al = a->top;
if (al <= 0) {
r->top = 0;
r->neg = 0;
return 1;
}
BN_CTX_start(ctx);
rr = (a != r) ? r : BN_CTX_get(ctx);
tmp = BN_CTX_get(ctx);
if (!rr || !tmp) {
goto err;
}
max = 2 * al; /* Non-zero (from above) */
if (!bn_wexpand(rr, max)) {
goto err;
}
if (al == 4) {
bn_sqr_comba4(rr->d, a->d);
} else if (al == 8) {
bn_sqr_comba8(rr->d, a->d);
} else {
if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
bn_sqr_normal(rr->d, a->d, al, t);
} else {
int j, k;
j = BN_num_bits_word((BN_ULONG)al);
j = 1 << (j - 1);
k = j + j;
if (al == j) {
if (!bn_wexpand(tmp, k * 2)) {
goto err;
}
bn_sqr_recursive(rr->d, a->d, al, tmp->d);
} else {
if (!bn_wexpand(tmp, max)) {
goto err;
}
bn_sqr_normal(rr->d, a->d, al, tmp->d);
}
}
}
rr->neg = 0;
/* If the most-significant half of the top word of 'a' is zero, then
* the square of 'a' will max-1 words. */
if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l)) {
rr->top = max - 1;
} else {
rr->top = max;
}
if (rr != r && !BN_copy(r, rr)) {
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}