Re: [boost] [Endian] Review

Subject: Re: [boost] [Endian] Review
From: Vicente Botet (vicente.botet_at_[hidden])
Date: 2011-09-09 02:32:22

Steven Watanabe-4 wrote:
> 
> AMDG
> 
> On 09/08/2011 12:23 PM, Beman Dawes wrote:
>> On Thu, Sep 8, 2011 at 1:18 PM, Tomas Puverle <
>> Tomas.Puverle_at_[hidden]> wrote:
>> 
>>>
>>> However, as I said, that's my personal preference and last year plenty
>>> of
>>> people wanted to see the operators included.  Perhaps they could be a
>>> policy?
>>>
>>> endian<..., bool EnableOperators_ > ?
>>>
>> 
>> I'll give it some thought, but my initial reaction is that endian is
>> already
>> more complex than I like, so I'm leery of adding yet more complexity.
>> 
> 
> If you don't want the operators, then don't use
> them.  Having an extra template parameter to
> disable them seems rather pointless.
> 

Hi,

I have separated the endian class into a endian_pack that is integer
agnostic and an endian class that behaves as an integer (You could see the
details in the Sandbox under endian_ext). 

Reference docs: 
http://svn.boost.org/svn/boost/sandbox/endian_ext/libs/integer/endian/doc/html/toward_boost_integer_endian/reference.html#toward_boost_integer_endian.reference.integer_endian_pack_hpp

http://svn.boost.org/svn/boost/sandbox/endian_ext/libs/integer/endian/doc/html

(Sorry but there is a bad link to the reference)

This is not complex and allows to define physical structures that can be
used only at the I/O frontier.

To separate the concerns and avoid the inefficient arithmetic on endian
integers, the example posted on another thread

struct file_header {
   big32_t n_things;
   ....
};

int main()
{
   file_header h;
   h.n_things = 0;
   while (....) {
     ++h.n_things;
     ....
   }
   write(h);
   ....
} 

could be rewritten as follows to force more efficient code 

struct file_header {
   big32_pt n_things;
   ....
};

where big32_pt is a typedef for a 32 bits
typedef endian_pack&lt;endianness::big, int_least32_t, 32,
alignment::unaligned&gt; big32_pt;

int main()
{
   file_header h;
   int n_things = 0;
   while (....) {
     ++n_things;
     ....
   }
   h.n_things = n_things;
   write(h);
   ....
} 

Best,
Vicente

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