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