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// Copyright 2024 Gabriel Bjørnager Jensen.
//
// This file is part of Pollex.
//
// Pollex is free software: you can redistribute it
// and/or modify it under the terms of the GNU Af-
// fero General Public License as published by the
// Free Software Foundation, either version 3 of
// the License, or (at your option) any later ver-
// sion.
//
// Pollex is distributed in the hope that it will
// be useful, but WITHOUT ANY WARRANTY; without
// even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Affero General Public License for more details.
//
// You should have received a copy of the GNU Af-
// fero General Public License along with Pollex.
// If not, see <https://www.gnu.org/licenses/>.
use alloc::string::String;
use core::fmt::{Display, Formatter};
/// Wrapping of [`core::result::Result`].
pub type Result<T> = core::result::Result<T, Error>;
/// A crate error.
#[derive(Clone, Debug)]
pub enum Error {
/// The given flag is currently not support.
///
/// Some Thumb instructions require the S flag to be on, for example.
/// These yield this error if encoded with the S flag is off.
IllegalFlag { reason: &'static str },
/// The given immediate cannot be encoded.
IllegalImmediate { reason: &'static str },
/// The given instruction cannot be encoded.
///
/// Even valid instructions are not valid in *every* case.
/// For example, most shifter operands and instruction predicates are **not** allowed in a Thumb context (with exceptions).
IllegalInstruction { reason: &'static str },
/// The given instruction predicate cannot be encoded.
IllegalPredicate { reason: &'static str },
/// The given register can currently not be used.
IllegalRegister { reason: &'static str },
/// The given shifter operand cannot be encoded.
IllegalShifter { reason: &'static str },
/// The provided opcode could not be decoded.
InvalidOpcode,
/// Mnemonic is not known.
UnknownMnemonic(String),
/// Register name is not known.
UnknownRegister(String),
}
impl Display for Error {
fn fmt(&self, f: &mut Formatter) -> core::fmt::Result {
use Error::*;
match *self {
IllegalFlag { reason } => write!(f, "illegal flag value: {reason}"),
IllegalImmediate { reason } => write!(f, "illegal immediate value: {reason}"),
IllegalInstruction { reason } => write!(f, "illegal instruction: {reason}"),
IllegalPredicate { reason } => write!(f, "illegal instruction predicate: {reason}"),
IllegalRegister { reason } => write!(f, "register not permitted here: {reason}"),
IllegalShifter { reason } => write!(f, "shifter operand not permitted here: {reason}"),
InvalidOpcode => write!(f, "invalid opcode"),
UnknownMnemonic(ref s) => write!(f, "unknown mnemonic `{s}`"),
UnknownRegister(ref s) => write!(f, "unknown register `{s}`"),
}
}
}
impl core::error::Error for Error { }
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