This is a Rust implementation of the UM-32 "Universal Machine". You can find the specification, various VM images, and more information about the contest which originally spawned this horror at boundvariable.org.
The Universal Machine consists of 8 unsigned 32 bit registers, a dynamically allocated heap containing arbitrarily sized arrays of unsigned 32 bit data, and 14 opcodes. Universal Machine images are stored as a sequence of unsigned 32 bit words with big-endian byte order.
This is an extremely naive implementation written as an exercise to become better acquainted with Rust. It's currently about an order of magnitude slower than a fast Universal Machine implementation. I'd like to correct this.
There is good coverage of the instruction parsing code, and no coverage of anything else. This will need to be fixed before trying to optimize.
This thing is about an order of magnitude slower than it should be: ``` [jgrillo@localhost um32]$ time ./target/release/um32 ~/src/boundvariable/umbin/midmark.um read 120440 bytes from /home/jgrillo/src/boundvariable/umbin/midmark.um == UM beginning stress test / benchmark.. == 4. 12345678.09abcdef 3. 6d58165c.2948d58d 2. 0f63b9ed.1d9c4076 1. 8dba0fc0.64af8685 0. 583e02ae.490775c0 Benchmark complete.
real 0m11.254s user 0m11.232s sys 0m0.007s
``
According to [this source](https://github.com/rlew/um/tree/master/ums), the
midmark.um` benchmark should run in "about one second".
These blog posts provide a helpful introduction to profiling Rust programs: 1. http://blog.adamperry.me/rust/2016/07/24/profiling-rust-perf-flamegraph/ 2. http://www.codeofview.com/fix-rs/2017/01/24/how-to-optimize-rust-programs-on-linux/