Author:

• Name: Gregor Richards
  Location: US - United States of America (United States)

To build:

    make

Bugs and (Mis)features:

The current status of this entry is:

STATUS: doesn’t work with some platforms - please help us fix it

For more detailed information see 2011/richards in bugs.html.

To use:

    echo expression | ./richards

Try:

    ./try.sh

Judges’ remarks:

Oh no, yet another dc-style calculator? (see 2000/dlowe using an embedded Perl interpreter and deemed Worst Abuse of the Rules). Well, this one does it (expression calculation, that is, not the rule abuse) in a different way. The author claims that his calculator does just-in-time compilation. What would you do to prove or disprove his claim without attempting to unravel the source?

Author’s remarks:

This is an implementation of the classic UNIX dc command, the reverse Polish calculator. Actually it’s a pretty bad implementation, since it only implements 32-bit integers (well, sizeof(int)-sized integers). It only implements the commands +, -, *, /, p (only for numbers), register stacks, macros and comparisons. Wow, you’d think I could’ve done better in 2K of code.

OH! I forgot to mention! It’s a JIT.

Wait, don’t stop reading! I know what you’re thinking, platform-specific code is discouraged in IOCCC. But do you see any platform-specific code? There’s no assembler here! This JIT works on a dozen platforms, and the only platform-specific assumptions it makes are that the stack grows down and integers are at least 32-bit.

You will probably get warnings while compiling the code. In particular:

• If your system requires the inclusion of alloca.h to use alloca, use the compile flag -DAH.

• If your system cannot use mmap(), use the compile flag -DNM.

• I don’t include any headers I don’t strictly need to, so you’ll get warnings about (at least) memcpy(), isdigit(), atoi(), calloc(), malloc() and alloca() if you didn’t use -DAH.

  • NOTE from judges: we added these includes in 2023.

• GCC likes to complain about while (a = b) (assignments as a condition).

• I don’t return from main(), even though it’s declared to return int.

Platforms on which all known/tested optimization levels work with no additional flags:

• gcc 4.6.2 + x86[_64] + GNU/Linux, Mac OS X or Windows
• clang 2.9-16 + x86[_64] + GNU/Linux or Mac OS X
• tcc 0.9.25
• gcc 4.4.5 + alpha, arm, mips[el], powerpc[64], s390x (IBM zSeries)
• gcc 4.1.3 + vax + NetBSD

Platforms which work but not at all optimization levels or needing special flags:

• owcc 1.9 + x86 + Windows: Needs -DNM -DAH -fno-stack-check
• gcc 4.4.5 + sh4: -O0 works, higher optimization levels don’t work for unknown reasons.

Primary files

• richards.c - entry source code
• Makefile - entry Makefile
• richards.alt.c - alternate source code
• richards.orig.c - original source code
• try.alt.sh - script to try alternate code
• try.sh - script to try entry

Secondary files

• 2011_richards.tar.bz2 - download entry tarball
• README.md - markdown source for this web page
• .entry.json - entry summary and manifest in JSON
• .gitignore - list of files that should not be committed under git
• .path - directory path from top level directory
• index.html - this web page

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