Jérôme M. Berger wrote:
> Ali Çehreli wrote:
>> � wrote:
>>
>>> The idea is to build a value that is between minA and maxA and will
>>> set as many bits as possible when or'ed with maxB:
>> The assumption that maxB would be the value that produces the maximum
>> a|b is not correct. A lower valued b may fill more gaps in the bit
>> representation of what is calculated from min_a and max_a.
>>
>> Your function failed for me with the following values:
>>
>> min_a 00000000000000000000000011001000 000000c8 200
>> max_a 00000000000000000000001100001111 0000030f 783
>> min_b 00000000000000000000000001000101 00000045 69
>> max_b 00000000000000000000001001100001 00000261 609
>> calculated 00000000000000000000001001100101 00000265 613
>> WRONG! empirical 00000000000000000000001111111111 000003ff 1023
>> emp_max_a 00000000000000000000000110011110 0000019e 414
>> emp_max_b 00000000000000000000001001100001 00000261 609
>>
>> Please see my test code elsewhere in the same thread: :)
>>
>>
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=108851
>>
> The "calculated" value above obviously was not computed with my
> function!
My mistake: It was your function but the highbit() that I used was not
correct. The one I used was returning the *value* of the highest bit.
> Since the return value from my function includes maxA and
> maxB, at least all bits that are set in either of those should be
> set in the output.
>
> I've run my code with those input and the result is 3ff as
> expected... (See attached source file).
Perhaps my test code is wrong; but I can't find my error. :/
Your function reports 0b_111 for these set of values:
min_a = 5;
max_a = 6;
min_b = 4;
max_b = 4;
But the maximum value of a|b is 6.
Ali
