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mod encoding;
mod heap;
mod value;
use encoding::{Arg, Op};
use heap::Heap;
use std::error::Error;
use std::ffi::OsString;
use std::io::{stdin, BufWriter, Read, Write};
use value::Value;
trait ReadArg {
fn read_arg(&self, a: Arg) -> Value;
}
impl ReadArg for Heap {
fn read_arg(&self, a: Arg) -> Value {
match a {
Arg::Local(l) => self.locals[usize::from(l)],
Arg::Const(c) => c,
}
}
}
fn write(
w: &mut impl Write,
heap: &Heap,
ptr: u8,
off: Arg,
len: Arg,
) -> Result<(), Box<dyn Error>> {
let Some(ptr) = heap.locals[usize::from(ptr)].to_pointer() else {
return Err(Box::from("write needs a pointer"));
};
let Some(ioff) = heap.read_arg(off).to_int() else {
return Err(Box::from("write needs an int"));
};
let Ok(off) = usize::try_from(ioff) else {
return Err(Box::from("write: off is negative"));
};
let Some(ilen) = heap.read_arg(len).to_int() else {
return Err(Box::from("write needs an int"));
};
let Ok(len) = usize::try_from(ilen) else {
return Err(Box::from("write: len is negative"));
};
for i in 0..len {
let Some(ibyte) = heap.peek(ptr + off + i)?.to_int() else {
return Err(Box::from("write: buffer has non-integer entries"));
};
let Ok(byte) = u8::try_from(ibyte) else {
return Err(Box::from("write: buffer entry is not between 0 and 255"));
};
w.write_all(&[byte])?;
}
w.flush()?;
Ok(())
}
struct State {
i: usize,
heap: Heap,
stdout: BufWriter<Box<dyn Write>>,
stderr: BufWriter<Box<dyn Write>>,
}
impl State {
fn op(&mut self, op: Op) -> Result<(), Box<dyn Error>> {
match op {
Op::Alloc(op) => {
let Some(i) = self.heap.read_arg(op.size).to_int() else {
return Err(Box::from("alloc needs an int"));
};
self.heap.locals[usize::from(op.out)] = Value::from_pointer(self.heap.alloc(i)?);
}
Op::Call => {
let Some(i) = self.heap.locals[0].to_int() else {
return Err(Box::from("call needs an int"));
};
self.i = usize::try_from(i)?;
}
Op::Poke(op) => {
let Some(p) = self.heap.locals[usize::from(op.ptr)].to_pointer() else {
return Err(Box::from("poke needs a pointer"));
};
self.heap.poke(p, op.offset, self.heap.read_arg(op.val))?;
}
Op::Peek(op) => {
let Some(p) = self.heap.read_arg(op.val).to_pointer() else {
return Err(Box::from("peek needs a pointer"));
};
self.heap.locals[usize::from(op.out)] = self.heap.peek(p + op.offset)?;
}
Op::Shuf(op) => {
self.heap.locals[usize::from(op.out)] = self.heap.read_arg(op.val);
}
Op::Exit(op) => {
let Some(i) = self.heap.read_arg(op.val).to_int() else {
std::process::exit(255);
};
std::process::exit(i as i32);
}
Op::Add(op) => {
let Some(v1) = self.heap.read_arg(op.val1).to_int() else {
return Err(Box::from("add needs an int"));
};
let Some(v2) = self.heap.read_arg(op.val2).to_int() else {
return Err(Box::from("add needs an int"));
};
self.heap.locals[usize::from(op.out)] = Value::from_int(v1.wrapping_add(v2));
}
Op::Sub(op) => {
let Some(v1) = self.heap.read_arg(op.val1).to_int() else {
return Err(Box::from("sub needs an int"));
};
let Some(v2) = self.heap.read_arg(op.val2).to_int() else {
return Err(Box::from("sub needs an int"));
};
self.heap.locals[usize::from(op.out)] = Value::from_int(v1.wrapping_sub(v2));
}
Op::Mul(op) => {
let Some(v1) = self.heap.read_arg(op.val1).to_int() else {
return Err(Box::from("mul needs an int"));
};
let Some(v2) = self.heap.read_arg(op.val2).to_int() else {
return Err(Box::from("mul needs an int"));
};
self.heap.locals[usize::from(op.out)] = Value::from_int(v1.wrapping_mul(v2));
}
Op::Div(op) => {
let Some(v1) = self.heap.read_arg(op.val1).to_int() else {
return Err(Box::from("div needs an int"));
};
let Some(v2) = self.heap.read_arg(op.val2).to_int() else {
return Err(Box::from("div needs an int"));
};
let Some(res) = v1.checked_div(v2) else {
return Err(Box::from("division by zero"));
};
self.heap.locals[usize::from(op.out)] = Value::from_int(res);
}
Op::Less(op) => {
let Some(v1) = self.heap.read_arg(op.val1).to_int() else {
return Err(Box::from("less needs an int"));
};
let Some(v2) = self.heap.read_arg(op.val2).to_int() else {
return Err(Box::from("less needs an int"));
};
let res = if v1 < v2 { 1 } else { 0 };
self.heap.locals[usize::from(op.out)] = Value::from_int(res);
}
Op::Eq(op) => {
let Some(v1) = self.heap.read_arg(op.val1).to_int() else {
return Err(Box::from("eq needs an int"));
};
let Some(v2) = self.heap.read_arg(op.val2).to_int() else {
return Err(Box::from("eq needs an int"));
};
let res = if v1 == v2 { 1 } else { 0 };
self.heap.locals[usize::from(op.out)] = Value::from_int(res);
}
Op::If(op) => {
let Some(t) = self.heap.read_arg(op.test).to_int() else {
return Err(Box::from("if needs an int"));
};
if t != 0 {
self.i = op.target;
}
}
Op::Read(op) => {
let Some(ptr) = self.heap.locals[usize::from(op.ptr)].to_pointer() else {
return Err(Box::from("read needs a pointer"));
};
let Some(ioff) = self.heap.read_arg(op.off).to_int() else {
return Err(Box::from("read needs an int"));
};
let Ok(off) = usize::try_from(ioff) else {
return Err(Box::from("read: off is negative"));
};
let Some(ilen) = self.heap.read_arg(op.len).to_int() else {
return Err(Box::from("read needs an int"));
};
let Ok(len) = usize::try_from(ilen) else {
return Err(Box::from("read: len is negative"));
};
let mut n = 0;
for byte in stdin().lock().bytes().take(len) {
let byte = byte?;
self.heap
.poke(ptr, off + n, Value::from_int(i64::from(byte)))?;
n += 1;
if byte == b'\n' {
break;
}
}
self.heap.locals[usize::from(op.out)] = Value::from_int(
i64::try_from(n)
.expect("we can never read more than len bytes, and len fit in an i64"),
);
}
Op::Write(op) => {
write(&mut self.stdout, &self.heap, op.ptr, op.off, op.len)?;
}
Op::WriteErr(op) => {
write(&mut self.stderr, &self.heap, op.ptr, op.off, op.len)?;
}
}
Ok(())
}
}
fn run() -> Result<(), Box<dyn Error>> {
let args: Vec<OsString> = std::env::args_os().collect();
if args.len() != 2 {
return Err(Box::from("usage: bytecode <file>"));
}
let prog = std::fs::read(&args[1])?;
let mut st = State {
i: 0,
heap: Heap::new(),
stdout: BufWriter::new(Box::new(std::io::stdout().lock())),
stderr: BufWriter::new(Box::new(std::io::stderr().lock())),
};
loop {
let (n, op) = Op::parse(&prog[st.i..])?;
st.i += n;
st.op(op)?;
}
}
fn main() {
if let Err(err) = run() {
let _ = writeln!(std::io::stderr(), "FAIL: {}", err);
std::process::exit(255);
}
}
|
