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Move |bn_div_words| to crypto/bn/div.c and make it static.

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It is only used by |bn_div_rem_words|.

Change-Id: I57627091d8db5890d7fea34d8560897717008646
Reviewed-on: https://boringssl-review.googlesource.com/7128
Reviewed-by: David Benjamin <davidben@google.com>
This commit is contained in:
Brian Smith 2016-02-14 10:12:05 -10:00 committed by David Benjamin
parent d1425f69df
commit cd8d1761df
3 changed files with 74 additions and 78 deletions
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74
crypto/bn/div.c
View File

@ -56,12 +56,86 @@
#include <openssl/bn.h>
#include <assert.h>
#include <limits.h>
#include <openssl/err.h>
#include "internal.h"
#if !defined(BN_ULLONG)
/* bn_div_words divides a double-width |h|,|l| by |d| and returns the result,
* which must fit in a |BN_ULONG|. */
static BN_ULONG bn_div_words(BN_ULONG h, BN_ULONG l, BN_ULONG d) {
BN_ULONG dh, dl, q, ret = 0, th, tl, t;
int i, count = 2;
if (d == 0) {
return BN_MASK2;
}
i = BN_num_bits_word(d);
assert((i == BN_BITS2) || (h <= (BN_ULONG)1 << i));
i = BN_BITS2 - i;
if (h >= d) {
h -= d;
}
if (i) {
d <<= i;
h = (h << i) | (l >> (BN_BITS2 - i));
l <<= i;
}
dh = (d & BN_MASK2h) >> BN_BITS4;
dl = (d & BN_MASK2l);
for (;;) {
if ((h >> BN_BITS4) == dh) {
q = BN_MASK2l;
} else {
q = h / dh;
}
th = q * dh;
tl = dl * q;
for (;;) {
t = h - th;
if ((t & BN_MASK2h) ||
((tl) <= ((t << BN_BITS4) | ((l & BN_MASK2h) >> BN_BITS4)))) {
break;
}
q--;
th -= dh;
tl -= dl;
}
t = (tl >> BN_BITS4);
tl = (tl << BN_BITS4) & BN_MASK2h;
th += t;
if (l < tl) {
th++;
}
l -= tl;
if (h < th) {
h += d;
q--;
}
h -= th;
if (--count == 0) {
break;
}
ret = q << BN_BITS4;
h = ((h << BN_BITS4) | (l >> BN_BITS4)) & BN_MASK2;
l = (l & BN_MASK2l) << BN_BITS4;
}
ret |= q;
return ret;
}
#endif /* !defined(BN_ULLONG) */
static inline void bn_div_rem_words(BN_ULONG *quotient_out, BN_ULONG *rem_out,
BN_ULONG n0, BN_ULONG n1, BN_ULONG d0) {
/* GCC and Clang generate function calls to |__udivdi3| and |__umoddi3| when

74
crypto/bn/generic.c
View File

@ -202,80 +202,6 @@ void bn_sqr_words(BN_ULONG *r, const BN_ULONG *a, int n) {
}
}
#if !defined(BN_ULLONG)
/* Divide h,l by d and return the result. */
BN_ULONG bn_div_words(BN_ULONG h, BN_ULONG l, BN_ULONG d) {
BN_ULONG dh, dl, q, ret = 0, th, tl, t;
int i, count = 2;
if (d == 0) {
return BN_MASK2;
}
i = BN_num_bits_word(d);
assert((i == BN_BITS2) || (h <= (BN_ULONG)1 << i));
i = BN_BITS2 - i;
if (h >= d) {
h -= d;
}
if (i) {
d <<= i;
h = (h << i) | (l >> (BN_BITS2 - i));
l <<= i;
}
dh = (d & BN_MASK2h) >> BN_BITS4;
dl = (d & BN_MASK2l);
for (;;) {
if ((h >> BN_BITS4) == dh) {
q = BN_MASK2l;
} else {
q = h / dh;
}
th = q * dh;
tl = dl * q;
for (;;) {
t = h - th;
if ((t & BN_MASK2h) ||
((tl) <= ((t << BN_BITS4) | ((l & BN_MASK2h) >> BN_BITS4)))) {
break;
}
q--;
th -= dh;
tl -= dl;
}
t = (tl >> BN_BITS4);
tl = (tl << BN_BITS4) & BN_MASK2h;
th += t;
if (l < tl) {
th++;
}
l -= tl;
if (h < th) {
h += d;
q--;
}
h -= th;
if (--count == 0) {
break;
}
ret = q << BN_BITS4;
h = ((h << BN_BITS4) | (l >> BN_BITS4)) & BN_MASK2;
l = (l & BN_MASK2l) << BN_BITS4;
}
ret |= q;
return ret;
}
#endif /* !defined(BN_ULLONG) */
#ifdef BN_ULLONG
BN_ULONG bn_add_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b,
int n) {

4
crypto/bn/internal.h
View File

@ -224,10 +224,6 @@ int bn_mul_mont(BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,
#error "Either BN_ULLONG or BN_UMULT_LOHI must be defined on every platform."
#endif
#if !defined(BN_ULLONG)
BN_ULONG bn_div_words(BN_ULONG h, BN_ULONG l, BN_ULONG d);
#endif
#if defined(__cplusplus)
} /* extern C */