Running Donald Knuth’s CWEB programs

I just realized that no-one documented how to quickly run Donald Knuth’s programs he publishes in his WEB system.

Suppose you want to compile a program like commafree; a program he wrote between September and December 2015 for his Annual Christmas tree lecture in 2015 about Universal Commafree Codes.

  1. Download the webfile which comprises documentation and source code.

  2. Recognize that the programming language used is C. Hence we need to use cweave and ctangle; not the original weave and tangle designed for Pascal.
    All those programs come bundled with TeX distributions like TeXLive. Once you have them installed and your system can find executables like pdflatex, it will also find cweave, etc.
  3. First, we generate the documentation.
    1. We run

      cweave commafree-eastman.w

      On my system this gives the output

      This is CWEAVE, Version 3.64 (TeX Live 2015/dev/Debian)
      Writing the output file...*1*3*8
      Writing the index...
      (No errors were found.)
    2. Three files are generated, namely commafree-eastman.idx, commafree-eastman.scn and commafree-eastman.tex.
    3. As a small remark, the TeX file uses the cwebmac definitions. So it is a file full of definitions and this file is also provided with your TeX distribution:
      % head -n 1 commafree-eastman.tex
      \input cwebmac
      % locate cwebmac
    4. Then we run the original tex program to build a dvi file.

      tex commafree-eastman.tex

      This gives me the output:

      This is TeX, Version 3.14159265 (TeX Live 2015/dev/Debian) (preloaded format=tex)
      (/usr/share/texlive/texmf-dist/tex/plain/cweb/cwebmac.tex) *1 [1] *3 [2]
      [3] *8 Index: (./commafree-eastman.idx) [4] Section names:
      (./commafree-eastman.scn) [5] Table of contents: (./commafree-eastman.toc)
      [0] )
      Output written on commafree-eastman.dvi (6 pages, 16116 bytes).
      Transcript written on commafree-eastman.log.
    5. Followingly, a file commafree-eastman.dvi is written as the output states. Opening it directly with evince 3.14.2 shows the output with some errors (the typical font encoding problems of TeX like < in #include statements is replaced by ¡). With okular 0.21.3 I can view the document without any problems.
    6. We convert the DVI file using the utility dvipdfm provided with your TeX distribution:
      dvipdfm commafree-eastman.dvi

      For me, this gives:

      commafree-eastman.dvi -> commafree-eastman.pdf
      45807 bytes written

      Then we have a PDF output file commafree-eastman.pdf containing the documentation.
      I think this is the usual way to view documents, you were looking for.

  4. We generate the source code:

    1. First we run ctangle:
      ctangle commafree-eastman.w

      which gives me:

      This is CTANGLE, Version 3.64 (TeX Live 2015/dev/Debian)
      Writing the output file (commafree-eastman.c):
      (No errors were found.)
    2. Nice! So we got a commafree-eastman.c file.
    3. We compile the C file with a C compile like the GCC:
      gcc -Wall -o commafree-eastman commafree-eastman.c

      This gives me:

      ./commafree-eastman.w:38:1: warning: return type defaults to ‘int’ [-Wreturn-type]
       main (int argc,char*argv[]) {
      ./commafree-eastman.w: In function ‘main’:
      ./commafree-eastman.w:42:1: warning: control reaches end of non-void function [-Wreturn-type]
    4. We run this new executable program:
      Usage: ./commafree-eastman x1 x2 ... xn

      This gives the same output as in the video.

So we got a commafree-eastman.pdf and commafree-eastman.c file which was what we were going for.
I will also refer here to my Literate programming talk at PyGraz back then.

Running Donald Knuth’s CWEB programs

2 thoughts on “Running Donald Knuth’s CWEB programs

  1. Heinz Prantner says:

    thx for the cookbook, very helpful!
    I tried to summarize in a Makefile:

    PI := 3 1 4 1 5 9 2 6 5 3 5 8 9 7 9
    commafree-eastman.tex: commafree-eastman.w
    	cweave commafree-eastman.w
    commafree-eastman.dvi: commafree-eastman.tex
    	tex commafree-eastman.tex
    commafree-eastman.pdf: commafree-eastman.dvi
    	dvipdfm commafree-eastman.dvi
    commafree-eastman.c: commafree-eastman.w
    	ctangle commafree-eastman.w
    commafree-eastman: commafree-eastman.c
    	gcc -Wall -o commafree-eastman commafree-eastman.c
    .PHONY : run
    run : commafree-eastman
    	./commafree-eastman $(PI)
    .PHONY : all
    all: commafree-eastman.pdf  run
    .PHONY : clean
    	rm -f commafree-eastman
    	rm -f commafree-eastman.c
    	rm -f commafree-eastman.pdf
    	rm -f commafree-eastman.log
    	rm -f commafree-eastman.toc
    	rm -f commafree-eastman.dvi
    	rm -f commafree-eastman.tex
    	rm -f commafree-eastman.idx
    	rm -f commafree-eastman.scn
    	rm -f commafree-eastman.w

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