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move places of casts

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This commit is contained in:
nora 2022-04-15 19:27:48 +02:00
parent 7dd2c82fa4
commit b535178cb8
1 changed files with 19 additions and 16 deletions
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35
rust2/src/codegen_interpreter.rs
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@ -2,15 +2,15 @@ use crate::codegen::{Code, Stmt};
use std::io::{Read, Write};
use std::num::Wrapping;
const MEM_SIZE: u32 = 32_000;
const MEM_SIZE: usize = 32_000;
type Memory = [Wrapping<u8>; MEM_SIZE as usize];
type Memory = [Wrapping<u8>; MEM_SIZE];
// TODO maybe repr(C) to prevent field reordering?
struct Interpreter<'c, W, R> {
code: &'c Code<'c>,
ip: u32,
ptr: u32,
ip: usize,
ptr: usize,
stdout: W,
stdin: R,
mem: Memory,
@ -27,7 +27,7 @@ where
ptr: 0,
stdout,
stdin,
mem: [Wrapping(0u8); MEM_SIZE as usize],
mem: [Wrapping(0u8); MEM_SIZE],
};
// SAFETY: `Code` can only be produced by the `crate::codegen` module, which is trusted to not
@ -44,8 +44,8 @@ impl<'c, W: Write, R: Read> Interpreter<'c, W, R> {
// SAFETY: If the code ends with an `End` and there are no out of bounds jumps,
// `self.ip` will never be out of bounds
// Removing this bounds check speeds up execution by about 40%
debug_assert!((self.ip as usize) < stmts.len());
let instr = unsafe { *stmts.get_unchecked(self.ip as usize) };
debug_assert!(self.ip < stmts.len());
let instr = unsafe { *stmts.get_unchecked(self.ip) };
self.ip += 1;
match instr {
Stmt::Add(n) => {
@ -55,17 +55,17 @@ impl<'c, W: Write, R: Read> Interpreter<'c, W, R> {
*self.elem_mut() -= n;
}
Stmt::Right(n) => {
self.ptr += n;
self.ptr += n as usize;
if self.ptr >= MEM_SIZE {
self.ptr = 0;
}
}
Stmt::Left(n) => {
if self.ptr < n {
let diff = n - self.ptr;
if self.ptr < n as usize {
let diff = n as usize - self.ptr;
self.ptr = MEM_SIZE - 1 - diff;
} else {
self.ptr -= n;
self.ptr -= n as usize;
}
}
Stmt::Out => {
@ -83,24 +83,27 @@ impl<'c, W: Write, R: Read> Interpreter<'c, W, R> {
}
Stmt::JmpIfZero(pos) => {
if self.elem() == 0 {
self.ip = pos;
self.ip = pos as usize;
}
}
Stmt::JmpIfNonZero(pos) => {
if self.elem() != 0 {
self.ip = pos;
self.ip = pos as usize;
}
}
Stmt::End => break,
}
}
}
fn elem_mut(&mut self) -> &mut Wrapping<u8> {
&mut self.mem[self.ptr as usize]
// SAFETY: `self.ptr` is never out of bounds
//debug_assert!(self.ptr < self.mem.len());
unsafe { self.mem.get_unchecked_mut(self.ptr) }
}
fn elem(&self) -> u8 {
self.mem[self.ptr as usize].0
// SAFETY: `self.ptr` is never out of bounds
//debug_assert!(self.ptr < self.mem.len());
unsafe { self.mem.get_unchecked(self.ptr).0 }
}
}