A one-pass compiler for a subset of C, relying on a recursive-descent parser, doing the lexing, parsing and code generation in lockstep. The generated code, consisting of abstract machine instructions, is then executed by an instruction fetch and execute loop.

BTW, the code looks relatively short because many semicolon-separated statements are crammed on a single line, and short variable names make that somewhat manageable and even visually symmetric. If you were to unfold it with each statement on its own line, I guess it would be at least 3 times the size.

AFAIK after taking a quick glance, it takes c code as input, then translates it to internal format by doing tokenization and parsing, and then executes the code. So, it's an interpreter. You could call it with other names as well. You can also have the program itself as an input, and have many layers of execution.