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disasm: improve branch ins helpers 

`branch_dest`: Support absolute destinations
`is_branch`: Use `matches!` to improve readability
`is_direct_branch`: Added helper to better match direct branches

Co-authored-by: Richard Patel <me@terorie.dev>
This commit is contained in:
InusualZ 2022-05-31 17:47:00 -04:00
parent a80372c1b6
commit 9fd7546916
1 changed files with 16 additions and 8 deletions
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24
disasm/src/lib.rs
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@ -229,6 +229,8 @@ pub struct Ins {
} }
impl Ins { impl Ins {
const BLR: u32 = 0x4e800020;
/// Constructs an instruction from the given machine code and address. /// Constructs an instruction from the given machine code and address.
pub fn new(code: u32, addr: u32) -> Self { pub fn new(code: u32, addr: u32) -> Self {
Self { Self {
@ -283,19 +285,24 @@ impl Ins {
pub fn branch_dest(&self) -> Option<u32> { pub fn branch_dest(&self) -> Option<u32> {
self.branch_offset().and_then(|offset| { self.branch_offset().and_then(|offset| {
if offset < 0 { if self.field_AA() {
self.addr.checked_sub((-offset) as u32) Some(offset as u32)
} else { } else {
self.addr.checked_add(offset as u32) if offset < 0 {
self.addr.checked_sub((-offset) as u32)
} else {
self.addr.checked_add(offset as u32)
}
} }
}) })
} }
pub fn is_branch(&self) -> bool { pub fn is_branch(&self) -> bool {
match self.op { matches!(self.op, Opcode::B | Opcode::Bc | Opcode::Bcctr | Opcode::Bclr)
Opcode::B | Opcode::Bc | Opcode::Bcctr | Opcode::Bclr => true, }
_ => false,
} pub fn is_direct_branch(&self) -> bool {
matches!(self.op, Opcode::B | Opcode::Bc)
} }
pub fn is_unconditional_branch(&self) -> bool { pub fn is_unconditional_branch(&self) -> bool {
@ -312,9 +319,10 @@ impl Ins {
self.is_branch() && !self.is_unconditional_branch() self.is_branch() && !self.is_unconditional_branch()
} }
#[inline]
pub fn is_blr(&self) -> bool { pub fn is_blr(&self) -> bool {
// self.op == Opcode::Bclr && self.is_unconditional_branch() && !self.field_LK() // self.op == Opcode::Bclr && self.is_unconditional_branch() && !self.field_LK()
self.code == 0x4e800020 self.code == Ins::BLR
} }
} }