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* bignum.c (bary_mul2): New function.

Browse source 
(rb_cstr_to_inum): Use a better algorithm to compose the result
  if input length is very long.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41726 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2013-07-01 13:59:50 +00:00
parent d08a79cfe1
commit df1192edf5
2 changed files with 119 additions and 22 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
Mon Jul 1 22:57:19 2013 Tanaka Akira <akr@fsij.org>
* bignum.c (bary_mul2): New function.
(rb_cstr_to_inum): Use a better algorithm to compose the result
if input length is very long.
Mon Jul 1 20:22:00 2013 Kenta Murata <mrkn@cookpad.com>
* ext/bigdecimal/bigdecimal.h (RB_UNUSED_VAR, UNREACHABLE):

101
bignum.c
View file

@ -92,16 +92,24 @@ static VALUE big_three = Qnil;
#define RBIGNUM_SET_NEGATIVE_SIGN(b) RBIGNUM_SET_SIGN(b, 0)
#define RBIGNUM_SET_POSITIVE_SIGN(b) RBIGNUM_SET_SIGN(b, 1)
#define KARATSUBA_MUL_DIGITS 70
#define TOOM3_MUL_DIGITS 150
static BDIGIT bary_small_lshift(BDIGIT *zds, BDIGIT *xds, long n, int shift);
static void bary_small_rshift(BDIGIT *zds, BDIGIT *xds, long n, int shift, int sign_bit);
static void bary_unpack(BDIGIT *bdigits, size_t num_bdigits, const void *words, size_t numwords, size_t wordsize, size_t nails, int flags);
static void bary_mul(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT *yds, size_t yl);
static void bary_mul2(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT *yds, size_t yl);
static void bary_sub(BDIGIT *zds, size_t zn, BDIGIT *xds, size_t xn, BDIGIT *yds, size_t yn);
static void bary_divmod(BDIGIT *qds, size_t nq, BDIGIT *rds, size_t nr, BDIGIT *xds, size_t nx, BDIGIT *yds, size_t ny);
static void bary_add(BDIGIT *zds, size_t zn, BDIGIT *xds, size_t xn, BDIGIT *yds, size_t yn);
static int bary_pack(int sign, BDIGIT *ds, size_t num_bdigits, void *words, size_t numwords, size_t wordsize, size_t nails, int flags);
static int bary_2comp(BDIGIT *ds, size_t n);
static void calc_hbase(int base, BDIGIT *hbase_p, int *hbase_numdigits_p);
static VALUE bigsqr_fast(VALUE x);
static VALUE bigmul0(VALUE x, VALUE y);
#define BIGNUM_DEBUG 0
#if BIGNUM_DEBUG
#define ON_DEBUG(x) do { x; } while (0)
@ -2039,6 +2047,7 @@ rb_cstr_to_inum(const char *str, int base, int badcheck)
}
else {
len = (len/BITSPERDIG)+1;
if (len < KARATSUBA_MUL_DIGITS) {
z = bignew(len, sign);
zds = BDIGITS(z);
for (i=len;i--;) zds[i]=0;
@ -2061,6 +2070,72 @@ rb_cstr_to_inum(const char *str, int base, int badcheck)
}
}
}
else {
BDIGIT hbase;
VALUE hbasev;
int hbase_numdigits;
int j;
size_t num_bdigits;
size_t unit;
VALUE tmpu = 0, tmpv = 0;
BDIGIT *uds, *vds, *tds;
calc_hbase(base, &hbase, &hbase_numdigits);
size = p - buf;
num_bdigits = roomof(size, hbase_numdigits);
uds = ALLOCV_N(BDIGIT, tmpu, num_bdigits);
vds = ALLOCV_N(BDIGIT, tmpv, num_bdigits);
hbasev = bignew(1, 1);
BDIGITS(hbasev)[0] = hbase;
i = 0;
while (buf < p) {
int m;
BDIGIT d = 0;
if (hbase_numdigits <= p - buf) {
m = hbase_numdigits;
}
else {
m = (int)(p - buf);
}
p -= m;
for (j = 0; j < m; j++) {
d = d * base + p[j];
}
uds[i++] = d;
}
for (unit = 1; unit < num_bdigits; unit *= 2) {
for (i = 0; i < num_bdigits; i += unit*2) {
if (2*unit <= num_bdigits - i) {
bary_mul2(vds+i, unit*2, BDIGITS(hbasev), RBIGNUM_LEN(hbasev), uds+i+unit, unit);
bary_add(vds+i, unit*2, vds+i, unit*2, uds+i, unit);
}
else if (unit <= num_bdigits - i) {
bary_mul2(vds+i, num_bdigits-i, BDIGITS(hbasev), RBIGNUM_LEN(hbasev), uds+i+unit, num_bdigits-(i+unit));
bary_add(vds+i, num_bdigits-i, vds+i, num_bdigits-i, uds+i, unit);
}
else {
MEMCPY(vds+i, uds+i, BDIGIT, num_bdigits-i);
}
}
hbasev = bigtrunc(bigmul0(hbasev, hbasev));
tds = vds;
vds = uds;
uds = tds;
}
while (0 < num_bdigits && uds[num_bdigits-1] == 0)
num_bdigits--;
z = bignew(num_bdigits, sign);
MEMCPY(BDIGITS(z), uds, BDIGIT, num_bdigits);
if (tmpv)
ALLOCV_END(tmpv);
if (tmpu)
ALLOCV_END(tmpu);
}
}
if (v)
ALLOCV_END(v);
@ -3617,6 +3692,9 @@ static void
bary_mul(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT *yds, size_t yl)
{
size_t l;
assert(xl + yl <= zl);
if (xl == 1 && yl == 1) {
l = 2;
bary_mul_single(zds, zl, xds[0], yds[0]);
@ -3628,7 +3706,24 @@ bary_mul(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT *yds, size_t yl)
MEMZERO(zds + l, BDIGIT, zl - l);
}
static VALUE bigmul0(VALUE x, VALUE y);
static void
bary_mul2(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT *yds, size_t yl)
{
assert(xl + yl <= zl);
if ((xl < yl ? xl : yl) < KARATSUBA_MUL_DIGITS)
bary_mul(zds, zl, xds, xl, yds, yl);
else {
VALUE x, y, z;
x = bignew(xl, 1);
MEMCPY(BDIGITS(x), xds, BDIGIT, xl);
y = bignew(yl, 1);
MEMCPY(BDIGITS(y), yds, BDIGIT, yl);
z = bigtrunc(bigmul0(x, y));
MEMCPY(zds, BDIGITS(z), BDIGIT, RBIGNUM_LEN(z));
MEMZERO(zds + RBIGNUM_LEN(z), BDIGIT, zl - RBIGNUM_LEN(z));
}
}
/* balancing multiplication by slicing larger argument */
static VALUE
@ -4066,10 +4161,6 @@ bigsqr_fast(VALUE x)
return z;
}
#define KARATSUBA_MUL_DIGITS 70
#define TOOM3_MUL_DIGITS 150
/* determine whether a bignum is sparse or not by random sampling */
static inline VALUE
big_sparse_p(VALUE x)