Commented valider

This commit is contained in:
Erin 2023-07-25 22:44:08 +02:00
parent f4c55ae3cc
commit ac149a5319

View file

@ -25,8 +25,8 @@ pub struct Error {
/// Perform bytecode validation. If it passes, the program should be
/// sound to execute.
pub fn validate(mut program: &[u8]) -> Result<(), Error> {
use hbbytecode::opcode::*;
// Program has to end with 12 zeroes, if there is less than
// 12 bytes, program is invalid.
if program.len() < 12 {
return Err(Error {
kind: ErrorKind::InvalidEnd,
@ -34,6 +34,7 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> {
});
}
// Verify that program ends with 12 zeroes
for (index, item) in program.iter().enumerate().skip(program.len() - 12) {
if *item != 0 {
return Err(Error {
@ -45,9 +46,14 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> {
let start = program;
loop {
use hbbytecode::opcode::*;
// Match on instruction types and perform necessary checks
program = match program {
// End of program
[] => return Ok(()),
// Memory load/store cannot go out-of-bounds register array
[LD..=ST, reg, _, _, _, _, _, _, _, _, count_0, count_1, ..]
if usize::from(*reg) * 8
+ usize::from(u16::from_le_bytes([*count_1, *count_0]))
@ -58,6 +64,8 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> {
index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
})
}
// Block register copy cannot go out-of-bounds register array
[BRC, src, dst, count, ..]
if src.checked_add(*count).is_none() || dst.checked_add(*count).is_none() =>
{
@ -66,6 +74,8 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> {
index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
})
}
// Valid instructions
[UN | NOP | ECALL, rest @ ..]
| [DIR | DIRF, _, _, _, _, rest @ ..]
| [ADD..=CMPU | BRC | ADDF..=MULF, _, _, _, rest @ ..]
@ -74,6 +84,8 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> {
| [ADDI..=XORI | CMPI..=CMPUI | BMC | JAL..=JGTU | ADDFI..=MULFI, _, _, _, _, _, _, _, _, _, _, rest @ ..]
| [SLI..=SRSI, _, _, _, _, rest @ ..]
| [LD..=ST, _, _, _, _, _, _, _, _, _, _, _, _, rest @ ..] => rest,
// The rest
_ => {
return Err(Error {
kind: ErrorKind::InvalidInstruction,