intcode

Intcode Interpreter

Usage

USAGE: intcode [-A | --ascii] [-d | --debug] [-B | --break] PROGRAM
Run Intcode PROGRAM in the interpreter.

-A, --ascii    use ASCII input/output
-d, --debug    enable debugging mode (traces execution and break into debugger on exceptions)
-B, --break    immediately break into debugger

The interpreter reads input from stdin and prints output to stdout. Interpreters can be linked together by piping the output of one interpreter into another.

# Run interpreter with fixed input
$ intcode $PROGRAM <<< 5

# Chain interpreters together
$ intcode $PROGRAM | intcode $PROGRAM

The easiest way of running from a git checkout is using cargo run -q --.

Debugger

If debugging is enabled (--debug) then exceptions will cause the interpreter to drop to a debugger.

$ intcode --debug $PROGRAM
00000000 ADD 0x00000000 0x00000000 0x00000000
ERROR: Illegal instruction 0 (ip: 0x00000004)
00000004 ???
debug>

The list of supported commands can be printed using help:

debug> help
p|print [ ADDR | $ip | $rb ]
                Print contents of address
c|continue      Continue execution
q|quit          Exit debugger and terminate program
d|disassemble   Disassemble current instruction
s|step          Step to the next instruction
i|input         Write input to the CPU
D|dump          Dump memory to console
h|help          Print this help

Using with binfmt_misc

You can register this binary as the handler of .intcode files on Linux by using binfmt_misc support in the kernel:

echo ':Intcode:E::intcode::/usr/local/bin/intcode:' > /proc/sys/fs/binfmt_mic/register

Day 7

An example of how this can be used to solve Day 7 by running this emulator in a series of shell pipelines.