Landon Curt Noll
f615bba21e
The commit 00ae59cd47 had a
mistake that introduces changes to Makefiles for 1996 thru 2020
that should not have been included.
This change reverses these intermediate changes until
the given year's Makefiles are ready.
Most surprisingly portable
Gregor Richards
Richards@codu.org
Judges' comments:
To build:
make richards
To run:
./richards
Try:
echo '10 9 8 7 6 5 4 3 2 1*p*p*p*p*p*p*p*p*p' | ./richards
Selected 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 comments:
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.
- 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.