Atomicity Post: 51097

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Top Forums Programming Atomicity Post 51097 by S.P.Prasad on Tuesday 11th of May 2004 01:33:28 AM

05-11-2004

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_check_lock and _clear_lock on AIX

I tested the code implementing the routines and the code behaves fine in Unit testing.

Also if someone can explain me in detail "The word variable must be aligned on a full word boundary." as stated in the page. Please correct me if I am worng - "A group of related bytes that are treated as a single addressable unit or entity in memory is called as a WORD. Hence size of a word varies from one computer to another, depending on the CPU. For computers with a 16-bit CPU, a word is 16 bits (2 bytes)."

Single Word = Single addressable unit by CPU
Word Boundary = Address completely divisible by number of bytes that represents a single addressable unit.

Example Single Word length = 16 bits then a word boundary is any address that is completely divisible by 16, which would mean that the variable referenced here should begin at 0,16,32,48,64 ... and so on memory locations and the variable should consume 16 bits of memory.

Am I correct? What extra care should I take into account during coding?

Please let me know whether these are a proven set of standard 'C' routines. Please let me know your honest opinions before I put it into the production system and have a go.

Thanks in advance

Last edited by S.P.Prasad; 05-11-2004 at 05:11 AM..

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LEARN ABOUT MINIX

ppmtosixel

ppmtosixel(1)                                                 General Commands Manual                                                ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.  The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
              pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order  of  magni-
              tude larger than a compressed file and prints much slower.

       -margin
              If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
              fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater  than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

                                                                   26 April 1991                                                     ppmtosixel(1)