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* bignum.c (bary_neg): Extracted from bary_2comp.

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(bary_plus_one): Extracted from bary_2comp.
  (bary_2comp): Use bary_neg and bary_plus_one.
  (big_extend_carry): Extracted from get2comp.
  (get2comp): Use big_extend_carry.
  (rb_integer_unpack): Use big_extend_carry.
  (rb_big_neg): Use bary_neg.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41695 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2013-06-29 14:38:26 +00:00
parent 69f1a3351f
commit 1522375b99
2 changed files with 38 additions and 14 deletions
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10
ChangeLog
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@ -1,3 +1,13 @@
Sat Jun 29 23:26:41 2013 Tanaka Akira <akr@fsij.org>
* bignum.c (bary_neg): Extracted from bary_2comp.
(bary_plus_one): Extracted from bary_2comp.
(bary_2comp): Use bary_neg and bary_plus_one.
(big_extend_carry): Extracted from get2comp.
(get2comp): Use big_extend_carry.
(rb_integer_unpack): Use big_extend_carry.
(rb_big_neg): Use bary_neg.
Sat Jun 29 22:31:59 2013 Tanaka Akira <akr@fsij.org> Sat Jun 29 22:31:59 2013 Tanaka Akira <akr@fsij.org>
* bignum.c (bary_2comp): Simplified. * bignum.c (bary_2comp): Simplified.

42
bignum.c
View File

@ -267,13 +267,17 @@ bytes_2comp(unsigned char *buf, size_t len)
return 1; return 1;
} }
static int static void
bary_2comp(BDIGIT *ds, size_t n) bary_neg(BDIGIT *ds, size_t n)
{ {
size_t i = n; while (n--)
if (!n) return 1; ds[n] = BIGLO(~ds[n]);
while (i--) ds[i] = BIGLO(~ds[i]); }
i = 0;
static int
bary_plus_one(BDIGIT *ds, size_t n)
{
size_t i;
for (i = 0; i < n; i++) { for (i = 0; i < n; i++) {
ds[i] = BIGLO(ds[i]+1); ds[i] = BIGLO(ds[i]+1);
if (ds[i] != 0) if (ds[i] != 0)
@ -282,6 +286,21 @@ bary_2comp(BDIGIT *ds, size_t n)
return 1; return 1;
} }
static int
bary_2comp(BDIGIT *ds, size_t n)
{
if (!n) return 1;
bary_neg(ds, n);
return bary_plus_one(ds, n);
}
static void
big_extend_carry(VALUE x)
{
rb_big_resize(x, RBIGNUM_LEN(x)+1);
BDIGITS(x)[RBIGNUM_LEN(x)-1] = 1;
}
/* modify a bignum by 2's complement */ /* modify a bignum by 2's complement */
static void static void
get2comp(VALUE x) get2comp(VALUE x)
@ -290,9 +309,7 @@ get2comp(VALUE x)
BDIGIT *ds = BDIGITS(x); BDIGIT *ds = BDIGITS(x);
if (bary_2comp(ds, i)) { if (bary_2comp(ds, i)) {
rb_big_resize(x, RBIGNUM_LEN(x)+1); big_extend_carry(x);
ds = BDIGITS(x);
ds[RBIGNUM_LEN(x)-1] = 1;
} }
} }
@ -1696,8 +1713,7 @@ rb_integer_unpack(const void *words, size_t numwords, size_t wordsize, size_t na
if (sign == -2) { if (sign == -2) {
if (val) { if (val) {
rb_big_resize(val, (long)num_bdigits+1); big_extend_carry(val);
BDIGITS(val)[num_bdigits] = 1;
} }
else if (num_bdigits == numberof(fixbuf)) { else if (num_bdigits == numberof(fixbuf)) {
val = bignew((long)num_bdigits+1, 0); val = bignew((long)num_bdigits+1, 0);
@ -3026,9 +3042,7 @@ rb_big_neg(VALUE x)
ds = BDIGITS(z); ds = BDIGITS(z);
i = RBIGNUM_LEN(x); i = RBIGNUM_LEN(x);
if (!i) return INT2FIX(~(SIGNED_VALUE)0); if (!i) return INT2FIX(~(SIGNED_VALUE)0);
while (i--) { bary_neg(ds, i);
ds[i] = BIGLO(~ds[i]);
}
RBIGNUM_SET_SIGN(z, !RBIGNUM_SIGN(z)); RBIGNUM_SET_SIGN(z, !RBIGNUM_SIGN(z));
if (RBIGNUM_SIGN(x)) get2comp(z); if (RBIGNUM_SIGN(x)) get2comp(z);