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Feature #8700 » bitlength.patch

akr (Akira Tanaka), 08/01/2013 08:47 PM

View differences:

bignum.c (working copy)
/*
* call-seq:
* big.bitlength -> integer
*
* Returns the number of bits of the absolute value of <i>big</i>.
*
* (-2**10000-1).bitlength #=> 10001
* (-2**10000).bitlength #=> 10001
* (-2**10000+1).bitlength #=> 10000
*
* (-2**1000-1).bitlength #=> 1001
* (-2**1000).bitlength #=> 1001
* (-2**1000+1).bitlength #=> 1000
*
* (2**1000-1).bitlength #=> 1000
* (2**1000).bitlength #=> 1001
* (2**1000+1).bitlength #=> 1001
*
* (2**10000-1).bitlength #=> 10000
* (2**10000).bitlength #=> 10001
* (2**10000+1).bitlength #=> 10001
*
*/
static VALUE
rb_big_bitlength(VALUE big)
{
int nlz_bits;
size_t numbytes;
static const BDIGIT char_bit[1] = { CHAR_BIT };
BDIGIT numbytes_bary[bdigit_roomof(sizeof(size_t))];
BDIGIT nlz_bary[1];
BDIGIT result_bary[bdigit_roomof(sizeof(size_t)+1)];
numbytes = rb_absint_size(big, &nlz_bits);
if (numbytes <= SIZE_MAX / CHAR_BIT) {
return SIZET2NUM(numbytes * CHAR_BIT - nlz_bits);
}
nlz_bary[0] = nlz_bits;
bary_unpack(BARY_ARGS(numbytes_bary), &numbytes, 1, sizeof(numbytes), 0,
INTEGER_PACK_NATIVE_BYTE_ORDER);
BARY_MUL1(result_bary, numbytes_bary, char_bit);
BARY_SUB(result_bary, result_bary, nlz_bary);
return rb_integer_unpack(result_bary, numberof(result_bary), sizeof(BDIGIT), 0,
INTEGER_PACK_LSWORD_FIRST|INTEGER_PACK_NATIVE_BYTE_ORDER);
}
/*
* call-seq:
* fix.bitlength -> integer
*
* Returns the number of bits of the absolute value of <i>fix</i>.
*
* (-2**12-1).bitlength) #=> 13
* (-2**12).bitlength) #=> 13
* (-2**12+1).bitlength) #=> 12
* -0x100.bitlength #=> 9
* -0xff.bitlength #=> 8
* -1.bitlength #=> 1
* 0.bitlength #=> 0
* 1.bitlength #=> 1
* 0xff.bitlength #=> 8
* 0x100.bitlength #=> 9
* (2**12-1).bitlength #=> 12
* (2**12).bitlength #=> 13
* (2**12+1).bitlength #=> 13
*/
static VALUE
rb_fix_bitlength(VALUE fix)
{
long v = FIX2LONG(fix);
if (v < 0)
v = -v;
return LONG2FIX(bitsize(v));
}
/*
* call-seq:
* big.odd? -> true or false
*
* Returns <code>true</code> if <i>big</i> is an odd number.
......
rb_define_method(rb_cBignum, "abs", rb_big_abs, 0);
rb_define_method(rb_cBignum, "magnitude", rb_big_abs, 0);
rb_define_method(rb_cBignum, "size", rb_big_size, 0);
rb_define_method(rb_cBignum, "bitlength", rb_big_bitlength, 0);
rb_define_method(rb_cBignum, "odd?", rb_big_odd_p, 0);
rb_define_method(rb_cBignum, "even?", rb_big_even_p, 0);
rb_define_method(rb_cFixnum, "bitlength", rb_fix_bitlength, 0);
power_cache_init();
}
test/ruby/test_fixnum.rb (working copy)
assert_raise(ZeroDivisionError, bug5713) { 0 ** -big }
assert_raise(ZeroDivisionError, bug5713) { 0 ** Rational(-2,3) }
end
def test_bitlength
assert_equal(13, (-2**12-1).bitlength)
assert_equal(13, (-2**12).bitlength)
assert_equal(12, (-2**12+1).bitlength)
assert_equal(9, -0x100.bitlength)
assert_equal(8, -0xff.bitlength)
assert_equal(1, -1.bitlength)
assert_equal(0, 0.bitlength)
assert_equal(1, 1.bitlength)
assert_equal(8, 0xff.bitlength)
assert_equal(9, 0x100.bitlength)
assert_equal(12, (2**12-1).bitlength)
assert_equal(13, (2**12).bitlength)
assert_equal(13, (2**12+1).bitlength)
end
end
test/ruby/test_bignum.rb (working copy)
end
assert_equal(T1024 ^ 10, T1024 ^ obj)
end
def test_bitlength
assert_equal(10001, (-2**10000-1).bitlength)
assert_equal(10001, (-2**10000).bitlength)
assert_equal(10000, (-2**10000+1).bitlength)
assert_equal(10000, (2**10000-1).bitlength)
assert_equal(10001, (2**10000).bitlength)
assert_equal(10001, (2**10000+1).bitlength)
1.upto(1000) {|i|
n = 2**i
assert_equal(i+1, (-n-1).bitlength)
assert_equal(i+1, (-n).bitlength)
assert_equal(i, (-n+1).bitlength)
assert_equal(i, (n-1).bitlength)
assert_equal(i+1, (n).bitlength)
assert_equal(i+1, (n+1).bitlength)
}
end
end
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