Note: this is mostly guesswork
I don't know this assembler but the f suffix seems to denote a label. Example
Those instructions write the parameters in the parameter zone of the system call.
note that there's a 0 label just after the sys instruction. It holds the parameters (copies of those which ...
Not an answer, as Jean-François Fabre has already deducted all workings, but some hints about the syntax/workings of AS to understand the source.
This source is meant to be assembled using the Unix assember AS. AS is an extreme primitive assembler designed only to handle machine specific parts of Unix. It carries only the most essential functions and those ...