Struct StdHost 

pub struct StdHost;

The Host behind MMix::new(): the process’s own I/O — locked stdout/stderr writes, stdout().flush() on halt, SystemTime for the clock, and eprintln! for diagnostics.

write_bytes_to_fd only ever calls Host::write with fd 1 or 2 (fd 3+ reads its File from file_handles), but StdHost is a general Host implementation, so it treats any other fd as an error rather than assuming that invariant.

Trait Implementations

impl Host for StdHost

fn write(&mut self, fd: u8, bytes: &[u8]) -> Result<()>

Write raw bytes to file descriptor fd (only 1 or 2 reach the host — see the trait docs). Returns Ok(()) on success, matching write_all rather than reporting a partial-write count. On success Fputs and Fputws store bytes.len() in $255; Fputc stores 0.

fn flush(&mut self)

Flush any buffered output. Halt is the only event that calls this, mirroring the process exiting without running destructors — a program that stops via an unsimulated TRAP or the TRIP instruction never reaches it, and MMix has no Drop. A host must not rely on flush for correctness. No-op by default.

fn now_micros(&mut self) -> u64

The current time in microseconds since the Unix epoch. The only clock primitive MMix needs — handle_time derives seconds and milliseconds from it by division.

fn diagnostic(&mut self, msg: &str)

Report an operator-facing diagnostic message (an unsimulated TRAP, a truncated string, a HALT/TRIP notice). StdHost sends these to stderr via eprintln!.

fn trap(&mut self, code: TrapCode, arg: u8, arg255: u64, result255: u64)

Observe a trap after handle_trap’s dispatch has run, with $255 captured both before and after. No-op by default.