Olin Lathrop wrote:
>>> A common method on a big system for reading a text protocol is to
>>> buffer up
>>> a line at a time, then parse it.  However when you really look at the
>>> parsing algorithm, most of it is sequentially reading the characters
>>> in the
>>> line.  With a little thought, you can usually eliminate or greatly
>>> reduce the buffer by processing the stream a byte at a time in the
>>> first place.
>>
>> There are two problems I see with this:
>>
>> 1. It is less straightforward.
>
> Huh?  I really can't imagine why either chunk processing or byte stream
> processing is inherently more "straight forward" than the other.  Byte
> stream processing lends itself particularly well to multi-tasking.  The 
> task
> runs in a infinite loops getting the next opcode byte, dispatching to the
> routine for that opcode, which may then branch further depending on 
> command
> options, etc.
[snip]

Olin, how is this "reusable"? Your "opcode dispatch" logic is superglued to 
your UART code.


> On a big system, there can be relatively high overhead just getting into 
> and
> out of the system call to get data, so getting a bunch of data at a time 
> is
> actually more efficient.  This isn't the case on a PIC.  On a PIC the
> "usual" get-buffer method is less efficient.  My main point, however, is
> that with the right mindset you can embrace the byte at a time phylosophy
> and write more efficient and just as elegant, reusable, maintainable, 
> cures
> cancer, etc, code as with the other mindset.

I don't see how. Of course sometimes it's necessary to do it the way you 
describe, because you don't have a choice (e.g., you don't have enough clock 
cycles or RAM). However, this approach basically forces you to write code 
that is inherently incohesive and tightly coupled.


> It just takes a different way
> of thinking about the whole problem, which apparently isn't easy for 
> people
> that grew up calling ReadFile.

[insert a counter-dig here] :o)

Vitaliy 

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