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====== Codeviz installation ====== ===== Background ===== When trying to understand what code does, it is often useful to create a graphical representation that shows how functions call each other. This kind of representation is often called a //call graph//. Codeviz is a tool that helps create call graphs. ===== Author's Website ===== I downloaded codeviz from this website: http://www.csn.ul.ie/~mel/projects/codeviz/ ===== Example call graph ===== Here is an example of a call graph for a function in gPXE: {{:doc:rtl8169_process_rx_packets.png?800|call graph example}} The function name is in the rectangular box on the left, and all the functions that are called flow to the right. I have limited the display to 3 levels of depth for presentation purposes. ===== Installation Procedure ===== <code> # Make sure we have graphviz and ncftp $ rpm -q graphviz ncftp # Fetch if needed $ sudo yum install graphviz ncftp $ wget http://www.csn.ul.ie/~mel/projects/codeviz/codeviz-1.0.11.tar.gz $ tar -xf codeviz-1.0.11.tar.gz $ cd codeviz-1.0.11 $ ./configure $ make $ sudo make install </code> The ''make'' command above downloads and builds gcc-3.4.6 from ''ftp.gnu.org''. It also installs ''genfull'' and ''gengraph'' in ''/usr/local/bin''. ===== Configuring for gPXE ===== To configure for gPXE you need to edit this line in src/Makefile.housekeeping: PRECIOUS : $(BIN)/%.tmp to be: PRECIOUS : $(BIN)/%.tmp $(BIN)/%.cdepn This causes .cdepn (C dependency) files to be kept. ===== Creating the .cdepn (C Dependency) files ===== First we get gccgraph to compile all the C files in gPXE. This is not too hard: $ cd gpxe.git/src $ make veryclean $ make CC=/usr/local/gccgraph/bin/gcc blib This will generate a .cdepn file for each .c file compiled. To see where they are do: $ find . -name "*.cdepn" Next we build the dependency database: $ genfull This creates the file ''full.graph'' in the current directory. ===== Creating nice call graphs ===== To make a nice call graph of ''rtl_open for instance'', we can do: $ gengraph -f rtl8169_poll -d 3 output-font=Arial --output-layout LR --plain This does a call graph of the function rtl8169_open, depth 3, left-to-right orientation, and requests that output be saved for input to the ''dot'' program. ''dot'' is the program that renders the outupt from gengraph: $ dot -Gcenter=1 -Gsize=11,8.5 -Gmargin=.333 -Tps -o rtl8169_poll.ps < rtl8169_poll.plain ''dot'' draw the call graph according to the instructions in the ''.plain'' file, and outputs a file in whatever -T says (postscript in this case. png is also popular). We can also request a ''.pdf'' be created from the ''.ps'' file using ''ps2pdf'': $ ps2pdf rtl_poll.ps ===== Automating the process ===== The three commands can be wrapped in a shell script command called ''mkcg'' such as: <code> #!/bin/sh gengraph -f ${1} -d 3 output-font=Arial --output-layout LR --plain dot -GPAPERSIZE=letter -Gsize=8,10.5 -Gcenter=1 -Gmargin=.25 -Tps -o ${1}.ps < ${1}.plain ps2pdf ${1}.ps rm ${1}.{ps,plain} </code> This makes the process of creating the ''.pdf'' a single command: $ mkcg rtl8169_poll ===== Combining pdf pages into one file ===== Ghostscript can combine separate PDF pages into a single file: $ gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=gpxe-call-graphs.pdf gpxe-api-call-graphs/*.pdf
