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Full Discussion: Grab exactly one byte from a FIFO, at random intervals
Top Forums Shell Programming and Scripting Grab exactly one byte from a FIFO, at random intervals Post 302747893 by vomv1988 on Sunday 23rd of December 2012 03:52:53 PM
Old 12-23-2012
Quote:
Originally Posted by bipinajith
This might sound stupid, but can you replace this section:
Code:
# This is 'grab1byte':
                INBYTE=`cat ${MY_FIFO}`
                echo The input byte is:
                printf "${INBYTE}" | xxd -cols 1 | sed 's/^.*: //'

with
Code:
# This is 'grab1byte':
                echo The input byte is:
                xxd -cols 1 ${MY_FIFO} | sed 's/^.*: //'

and give it another try? Let us know the result please.
The output is the same with that change, but thanks for trying anyway. After removing the sed filter from the original script I posted, the output looks something like:

Code:
y: print next byte
n: don't print next byte
q: quit
y
The input byte is:
0000000: 48  H
0000001: 65  e
y: print next byte
n: don't print next byte
q: quit
y
The input byte is:
0000000: 6c  l
0000001: 6c  l
0000002: 6f  o
0000003: 2c  ,
0000004: 20   
0000005: 77  w
y: print next byte
n: don't print next byte
q: quit

So this means that the FIFO buffer contains several bytes instead of just one... Which is weird, because, I thought 'printf "${CHAR}" > ${MY_FIFO}"' was supposed to pause the loop execution, UNTIL FIFO was emptied by something like 'cat ${MY_FIFO}'. After cat-ing FIFO, I thought the loop would freeze again at 'printf "${CHAR}" > ${MY_FIFO}"', until another instance of 'cat ${MY_FIFO}', but, apparently it doesn't. Apparently, it just feeds FIFO a random amount of bytes... WHY???

---------- Post updated at 04:52 PM ---------- Previous update was at 04:44 PM ----------

I'm thinking, maybe, cat opens up the FIFO for a longer time than it takes the loop to iterate, so the loop iterates several times, spitting several bytes into FIFO, until cat stops reading from FIFO (that is, until FIFO's output is closed)... Does this make any sense to you? And, if that is the case: How would I prevent that from happening?
 

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LEARN ABOUT DEBIAN

graphics::primitive::insets

Graphics::Primitive::Insets(3pm)			User Contributed Perl Documentation			  Graphics::Primitive::Insets(3pm)

NAME

       Graphics::Primitive::Insets - Space between things

DESCRIPTION

       Graphics::Primitive::Insets represents the amount of space that surrounds something.  This object can be used to represent either padding
       or margins (in the CSS sense, one being inside the bounding box, the other being outside)

SYNOPSIS

	 use Graphics::Primitive::Insets;

	 my $insets = Graphics::Primitive::Insets->new({
	   top	   => 5,
	   bottom  => 5,
	   left    => 5,
	   right   => 5
	 });

METHODS

   Constructor
       new Creates a new Graphics::Primitive::Insets.

   Instance Methods
       as_array
	   Return these insets as an array in the form of top, right, bottom and left.

       bottom
	   Set/Get the inset from the bottom.

       equal_to
	   Determine if these Insets are equal to another.

       left
	   Set/Get the inset from the left.

       right
	   Set/Get the inset from the right.

       top Set/Get the inset from the top.

       zero
	   Sets all the insets (top, left, bottom, right) to 0.

AUTHOR

       Cory Watson, "<gphat@cpan.org>"

SEE ALSO

       perl(1)

COPYRIGHT &; LICENSE
       Copyright 2008-2010 by Cory G Watson.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.12.3							    2010-08-21					  Graphics::Primitive::Insets(3pm)
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