81 lines
1.9 KiB
Rust
81 lines
1.9 KiB
Rust
use crate::vm::{error::*, reg::*};
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use byteorder::{ReadBytesExt, LE};
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use std::{
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io::Cursor,
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ops::{Deref, DerefMut},
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};
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const R1_MASK: u16 = 0b1111_1100_0000_0000;
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const R2_MASK: u16 = 0b0000_0011_1111_0000;
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pub struct MemCursor<'mem> {
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cursor: Cursor<&'mem [u8]>,
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}
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impl<'mem> MemCursor<'mem> {
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pub fn new(mem: &'mem [u8]) -> Self {
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MemCursor {
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cursor: Cursor::new(mem),
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}
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}
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pub fn cursor(&self) -> &Cursor<&'mem [u8]> {
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&self.cursor
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}
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pub fn cursor_mut(&mut self) -> &mut Cursor<&'mem [u8]> {
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&mut self.cursor
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}
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pub fn next_u8(&mut self) -> Result<u8> {
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self.read_u8().map_err(|_| VmError::MemOutOfBounds {
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addr: self.position(),
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})
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}
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pub fn next_u16(&mut self) -> Result<u16> {
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self.read_u16::<LE>().map_err(|_| VmError::MemOutOfBounds {
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addr: self.position(),
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})
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}
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pub fn next_u32(&mut self) -> Result<u32> {
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self.read_u32::<LE>().map_err(|_| VmError::MemOutOfBounds {
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addr: self.position(),
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})
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}
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pub fn next_u64(&mut self) -> Result<u64> {
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self.read_u64::<LE>().map_err(|_| VmError::MemOutOfBounds {
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addr: self.position(),
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})
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}
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pub fn next_regs(&mut self) -> Result<(Reg, Reg)> {
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let next16 = self.next_u16()?;
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let r1 = ((R1_MASK & next16) >> 10) as Reg;
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let r2 = ((R2_MASK & next16) >> 4) as Reg;
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Ok((r1, r2))
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}
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pub fn next_reg(&mut self) -> Result<Reg> {
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let next16 = self.next_u16()?;
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let r1 = ((R1_MASK & next16) >> 10) as Reg;
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Ok(r1)
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}
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}
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impl<'mem> Deref for MemCursor<'mem> {
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type Target = Cursor<&'mem [u8]>;
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fn deref(&self) -> &Self::Target {
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self.cursor()
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}
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}
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impl<'mem> DerefMut for MemCursor<'mem> {
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fn deref_mut(&mut self) -> &mut Self::Target {
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self.cursor_mut()
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}
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}
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