Back to the Future Award

Yusuke Endoh
https://github.com/mame/
Twitter: @mametter

Judges' comments:

To use:

make 

./prog

Try:

make -B BACK_TO=ioccc.c

./prog

Selected Judges Remarks:

Like Marty and Doc, something nostalgic from 1984 appears live in October of 2015! The author of this gem is a true Delorean!

A question for inquisitive readers: is the implemented subset of PDP-11 instructions Turing-complete? (For a clue, see the end of the author’s remarks.) If in doubt, use APOUT.

Author’s comments:

Hint / Compatibility

Spoiler

This program is a joke PDP-11 emulator. (“ll-dpd” is embedded in the code. Read it upside down.)

You got it? This program is supposed to be used in this way:

$ wget http://ioccc.org/1984/mullender.c
$ clang -o prog prog.c mullender.c
$ ./prog

You can enjoy the legendary winner of the first IOCCC, again.

Internal

This program uses __attribute__((constructor)), which is a GCC extension, to hijack the main function call. And then it interprets main as an instruction sequence.

It supports the minimal subset of instructions and addressing modes which are needed for mullender.c to work:

Limitation

Non-trivial combination of instruction and addressing mode may cause undefined behavior (unsequenced modification), such as attempting to autoincrement a destination register. Index addressing mode works well only for R7 (PC register).

One more thing

Note: the program writes a binary to stdout.

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Creative Commons License

© Copyright 1984-2016, Leo Broukhis, Simon Cooper, Landon Curt Noll - All rights reserved
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.