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author | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2013-07-22 18:35:27 +0000 |
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committer | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2013-07-22 18:35:27 +0000 |
commit | fdb991b9a0d75f08288d8c9fbd2f5e7404e5b2eb (patch) | |
tree | f16be272ff706f0ddea5c1f5192bd3beedcd20dc /bignum.c | |
parent | 2c2cb6852b383c54390343c92a05deadbcdd7bfe (diff) | |
download | ruby-fdb991b9a0d75f08288d8c9fbd2f5e7404e5b2eb.tar.gz |
* bignum.c (KARATSUBA_BALANCED): New macro.
(TOOM3_BALANCED): Ditto.
(bary_mul_balance_with_mulfunc): Use KARATSUBA_BALANCED and
TOOM3_BALANCED.
(rb_big_mul_balance): Relax a condition.
(rb_big_mul_karatsuba): Use KARATSUBA_BALANCED.
(rb_big_mul_toom3): Use TOOM3_BALANCED.
(bary_mul_karatsuba_branch): Use KARATSUBA_BALANCED.
(bary_mul_toom3_branch): Use TOOM3_BALANCED.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42122 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'bignum.c')
-rw-r--r-- | bignum.c | 20 |
1 files changed, 11 insertions, 9 deletions
@@ -121,6 +121,9 @@ STATIC_ASSERT(sizeof_long_and_sizeof_bdigit, SIZEOF_BDIGITS % SIZEOF_LONG == 0); } \ } while (0) +#define KARATSUBA_BALANCED(xn, yn) ((yn)/2 < (xn)) +#define TOOM3_BALANCED(xn, yn) (((yn)+2)/3 * 2 < (xn)) + #define KARATSUBA_MUL_DIGITS 70 #define TOOM3_MUL_DIGITS 150 @@ -1669,7 +1672,8 @@ bary_mul_balance_with_mulfunc(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BD size_t r, n; assert(xl + yl <= zl); - assert(2 * xl <= yl || 3 * xl <= 2*(yl+2)); + assert(xl <= yl); + assert(!KARATSUBA_BALANCED(xl, yl) || !TOOM3_BALANCED(xl, yl)); BDIGITS_ZERO(zds, xl); @@ -1713,8 +1717,6 @@ rb_big_mul_balance(VALUE x, VALUE y) { size_t xn = RBIGNUM_LEN(x), yn = RBIGNUM_LEN(y), zn = xn + yn; VALUE z = bignew(zn, RBIGNUM_SIGN(x)==RBIGNUM_SIGN(y)); - if (!(2 * xn <= yn || 3 * xn <= 2*(yn+2))) - rb_raise(rb_eArgError, "invalid bignum length"); bary_mul_balance_with_mulfunc(BDIGITS(z), zn, BDIGITS(x), xn, BDIGITS(y), yn, NULL, 0, bary_mul_toom3_start); RB_GC_GUARD(x); RB_GC_GUARD(y); @@ -1895,8 +1897,8 @@ rb_big_mul_karatsuba(VALUE x, VALUE y) { size_t xn = RBIGNUM_LEN(x), yn = RBIGNUM_LEN(y), zn = xn + yn; VALUE z = bignew(zn, RBIGNUM_SIGN(x)==RBIGNUM_SIGN(y)); - if (!(xn <= yn && yn < 2 * xn)) - rb_raise(rb_eArgError, "invalid bignum length"); + if (!(xn <= yn && yn < 2 || KARATSUBA_BALANCED(xn, yn))) + rb_raise(rb_eArgError, "unexpected bignum length for karatsuba"); bary_mul_karatsuba(BDIGITS(z), zn, BDIGITS(x), xn, BDIGITS(y), yn, NULL, 0); RB_GC_GUARD(x); RB_GC_GUARD(y); @@ -2299,8 +2301,8 @@ rb_big_mul_toom3(VALUE x, VALUE y) { size_t xn = RBIGNUM_LEN(x), yn = RBIGNUM_LEN(y), zn = xn + yn; VALUE z = bignew(zn, RBIGNUM_SIGN(x)==RBIGNUM_SIGN(y)); - if (xn > yn || yn < 3 || !((yn+2)/3 * 2 < xn)) - rb_raise(rb_eArgError, "invalid bignum length"); + if (xn > yn || yn < 3 || !TOOM3_BALANCED(xn,yn)) + rb_raise(rb_eArgError, "unexpected bignum length for toom3"); bary_mul_toom3(BDIGITS(z), zn, BDIGITS(x), xn, BDIGITS(y), yn, NULL, 0); RB_GC_GUARD(x); RB_GC_GUARD(y); @@ -2453,7 +2455,7 @@ bary_mul_karatsuba_branch(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT } /* balance multiplication by slicing y when x is much smaller than y */ - if (2 * xl <= yl) { + if (!KARATSUBA_BALANCED(xl, yl)) { bary_mul_balance_with_mulfunc(zds, zl, xds, xl, yds, yl, wds, wl, bary_mul_karatsuba_start); return; } @@ -2479,7 +2481,7 @@ bary_mul_toom3_branch(BDIGIT *zds, size_t zl, BDIGIT *xds, size_t xl, BDIGIT *yd return; } - if (3*xl <= 2*(yl + 2)) { + if (!TOOM3_BALANCED(xl, yl)) { bary_mul_balance_with_mulfunc(zds, zl, xds, xl, yds, yl, wds, wl, bary_mul_toom3_start); return; } |