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PL/0源码

This file contains source for the Rochester PL/0 compiler.
It was updated in July of 1999.

To make your own copy of the compiler for CSC 254/454:

(1) add ~cs254/bin and ~cs254/plzero/bin to your PATH environment
    variable.  You should make this a permanent change by editing the
    .cshrc file in your home directory.  Somewhere in this file there
    should be a line that says something like this:

        set path = ( . ~/bin /usr/bin )

    or
         setenv PATH ."$PATH":~/xdiff

    (Actually, it probably has more things in it than that.)
    Put ~cs254/bin and ~cs254/plzero/bin early in the list,
    e.g. right after '.'.

(2) execute the shell script ~cs254/plzero/src/NEWUSER in an empty
    directory in which you want to work.  E.g.:

        mkdir ~/plzero
        cd ~/plzero
        ~cs254/plzero/src/NEWUSER

    This script will take a while to run.  It will generate a lot of
    output on your screen, so you can watch it in action.  When it
    finishes, you should have two subdirectories, src and test.
    If you get an error message complaining about not being able to
    find g++ or scangen, then you got the PATH change wrong in step (1)
    above.

    The src directory will contain a working version of the compiler,
    with initial versions of the code checked into an RCS subdirectory.
    (If you haven't learned how to use RCS, learn now!  Read the man
    pages for 'ci', 'co', 'rcs', rlog', and 'rcsdiff', in that order.)

    The test directory will contain a symlink to the compiler, together
    with a small number of sample PL/0 programs.  (Additional programs
    can be found under ~cs254/plzero/test.)  To try out the compiler on,
    say, primes.0, type

        cd ~/plzero/test
        pl0 primes.0
        spim -file "primes.s"

    This particular program reads a positive integer N from the
    keyboard and prints the first N primes.