ds-decomp 0.11.0

Library for ds-decomp, a DS decompilation toolkit.
Documentation 
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use unarm::{
    Ins, ParsedIns,
    args::{Argument as Arg, OffsetReg, Reg, Register},
};

/// Detects illegal code sequences that never appears in any game.
#[derive(Clone, Copy, Default, PartialEq, Eq, Debug)]
pub enum IllegalCodeState {
    #[default]
    Start,
    ShiftedRegisterValue {
        reg: Register,
    },
    Illegal,
}

impl IllegalCodeState {
    pub fn handle(self, ins: Ins, parsed_ins: &ParsedIns) -> Self {
        if ins.is_illegal() || parsed_ins.is_illegal() {
            return Self::Illegal;
        }

        let args = &parsed_ins.args;
        match (self, ins.mnemonic(), args[0], args[1], args[2]) {
            // Find registers with shifted value
            (_, "lsl", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "lsls", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "lsr", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "lsrs", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "asr", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "asrs", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "ror", Arg::Reg(Reg { reg, .. }), _, _)
            | (_, "rors", Arg::Reg(Reg { reg, .. }), _, _) => Self::ShiftedRegisterValue { reg },

            // Dereferencing shifted registers
            (Self::ShiftedRegisterValue { reg }, "stm", Arg::Reg(Reg { reg: base, .. }), _, _)
            | (
                Self::ShiftedRegisterValue { reg },
                "stmia",
                Arg::Reg(Reg { reg: base, .. }),
                _,
                _,
            ) if reg == base => Self::Illegal,

            // Dereferencing registers offset by the same register
            (
                _,
                "str",
                _,
                Arg::Reg(Reg { deref: true, reg: base, .. }),
                Arg::OffsetReg(OffsetReg { reg: offset, .. }),
            ) if base == offset => Self::Illegal,

            _ => Self::default(),
        }
    }

    pub fn is_illegal(self) -> bool {
        self == Self::Illegal
    }
}