echo '10 9 8 7 6 5 4 3 2 1*p*p*p*p*p*p*p*p*p' | ./richards
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?
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:
Platforms on which all known/tested optimization levels work with no additional flags:
Platforms which work but not at all optimization levels or needing special flags:
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Leo Broukhis, Simon Cooper, Landon Curt Noll
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