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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.arch
Subject: Re: Computer architects leaving Intel...
Date: Sun, 8 Sep 2024 15:10:05 -0700
Organization: A noiseless patient Spider
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On 9/6/2024 4:10 PM, MitchAlsup1 wrote:
> On Fri, 6 Sep 2024 22:41:12 +0000, Chris M. Thomasson wrote:
> 
>> On 9/5/2024 10:04 AM, Terje Mathisen wrote:
>>> David Brown wrote:
>>>> On 05/09/2024 11:12, Terje Mathisen wrote:
>>>>> David Brown wrote:
>>>>>> Unsigned types are ideal for "raw" memory access or external data,
>>>>>> for anything involving bit manipulation (use of &, |, ^, << and >>
>>>>>> on signed types is usually wrong, IMHO), as building blocks in
>>>>>> extended arithmetic types, for the few occasions when you want two's
>>>>>> complement wrapping, and for the even fewer occasions when you
>>>>>> actually need that last bit of range.
>>>>>
>>>>> That last paragraph enumerates pretty much all the uses I have for
>>>>> integer-type variables, with (like Mitch) a few apis that use (-1) as
>>>>> an error signal that has to be handled with special code.
>>>>>
>>>>
>>>> You don't have loop counters, array indices, or integer arithmetic?
>>>
>>> Loop counters of the for (i= 0; i < LIMIT; i++) type are of course fine
>>> with unsigned i, arrays always use a zero base so in Rust the only array
>>> index type is usize, i.e the largest supported unsigned type in the
>>> system, typically the same as u64.
>>>
>>> unsigned arithmetic is easier than signed integer arithmetic, including
>>> comparisons that would result in a negative value, you just have to make
>>> the test before subtracting, instead of checking if the result was
>>> negative.
>>>
>>> I.e I cannot easily replicate a downward loop that exits when the
>>> counter become negative:
>>>
>>>    for (int i = START; i >= 0; i-- ) {
>>>      // Do something with data[i]
>>>    }
>>
>> for (int i = START; i > -1; i-- ) {
>>       // Do something with data[i]
>> }
>>
>> ;^)
> 
> # define START 0x80000001
[...]

In reverse? ;^)
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std::size_t n = m_lock_idxs.size();

for (std::size_t i = 0; i < n; ++i)
{
    m_mtx_tbl.m_locks[m_lock_idxs[n - i - 1]].unlock();
}
______________