forked from AbleOS/holey-bytes
320 lines
11 KiB
Rust
320 lines
11 KiB
Rust
//! Functions for inserting instructions
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//!
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//! Most of the code you see is just metaprogramming stuff.
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//! This ensures that adding new instructions won't need any
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//! specific changes and consistent behaviour.
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//!
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//! > I tried to comment stuff here, but I meanwhile forgor how it works.
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//!
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//! — Erin
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use {
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crate::object::Object,
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rhai::{FuncRegistration, Module},
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std::{cell::RefCell, rc::Rc},
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};
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/// Operand types and their insertions
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pub mod optypes {
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use {
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crate::{
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label::UnboundLabel,
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object::{Object, RelocKey, RelocType, SymbolRef},
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},
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rhai::{Dynamic, EvalAltResult, ImmutableString, Position},
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};
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// These types represent operand types to be inserted
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pub type R = u8;
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pub type B = i8;
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pub type H = i16;
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pub type W = i32;
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pub type D = i64;
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pub type A = Dynamic;
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pub type O = Dynamic;
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pub type P = Dynamic;
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/// Insert relocation into code
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///
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/// - If integer, just write it to the code
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/// - Otherwise insert entry into relocation table
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/// and fill zeroes
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pub fn insert_reloc(
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obj: &mut Object,
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ty: RelocType,
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val: &Dynamic,
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) -> Result<(), EvalAltResult> {
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match () {
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// Direct references – insert directly to table
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_ if val.is::<SymbolRef>() => {
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obj.relocation(RelocKey::Symbol(val.clone_cast::<SymbolRef>().0), ty)
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}
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_ if val.is::<UnboundLabel>() => {
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obj.relocation(RelocKey::Symbol(val.clone_cast::<UnboundLabel>().0), ty)
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}
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_ if val.is::<DataRef>() => {
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obj.relocation(RelocKey::Symbol(val.clone_cast::<DataRef>().symbol.0), ty)
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}
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// String (indirect) reference
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_ if val.is_string() => {
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obj.relocation(RelocKey::Label(val.clone_cast::<ImmutableString>()), ty)
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}
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// Manual offset
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_ if val.is_int() => {
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let int = val.clone_cast::<i64>();
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match ty {
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RelocType::Rel32 => obj.sections.text.extend((int as i32).to_le_bytes()),
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RelocType::Rel16 => obj.sections.text.extend((int as i16).to_le_bytes()),
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RelocType::Abs64 => obj.sections.text.extend(int.to_le_bytes()),
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}
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}
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_ => {
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return Err(EvalAltResult::ErrorMismatchDataType(
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"SymbolRef, UnboundLabel, String or Int".to_owned(),
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val.type_name().to_owned(),
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Position::NONE,
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))
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}
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}
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Ok(())
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}
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/// Generate macro for inserting item into the output object
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///
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/// Pre-defines inserts for absolute address and relative offsets.
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/// These are inserted with function [`insert_reloc`]
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/// # le_bytes
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/// `gen_insert!(le_bytes: [B, …]);`
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///
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/// Takes sequence of operand types which should be inserted
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/// by invoking `to_le_bytes` method on it.
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macro_rules! gen_insert {
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(le_bytes: [$($lety:ident),* $(,)?]) => {
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/// `insert!($thing, $obj, $type)` where
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/// - `$thing`: Value you want to insert
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/// - `$obj`: Code object
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/// - `$type`: Type of inserted value
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///
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/// Eg. `insert!(69_u8, obj, B);`
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macro_rules! insert {
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$(($thing:expr, $obj: expr, $lety) => {
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$obj.sections.text.extend($thing.to_le_bytes());
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};)*
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($thing:expr, $obj:expr, A) => {
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$crate::ins::optypes::insert_reloc(
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$obj,
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$crate::object::RelocType::Abs64,
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$thing
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)?
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};
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($thing:expr, $obj:expr, O) => {
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$crate::ins::optypes::insert_reloc(
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$obj,
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$crate::object::RelocType::Rel32,
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$thing
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)?
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};
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($thing:expr, $obj:expr, P) => {
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$crate::ins::optypes::insert_reloc(
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$obj,
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$crate::object::RelocType::Rel16,
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$thing
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)?
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};
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}
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};
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}
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gen_insert!(le_bytes: [R, B, H, W, D]);
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#[allow(clippy::single_component_path_imports)]
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pub(super) use insert;
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use crate::data::DataRef;
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}
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/// Rhai Types (types for function parameters as Rhai uses only 64bit signed integers)
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pub mod rity {
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pub use super::optypes::{A, O, P, R};
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pub type B = i64;
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pub type H = i64;
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pub type W = i64;
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pub type D = i64;
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}
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/// Generic instruction (instruction of certain operands type) inserts
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pub mod generic {
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use {crate::object::Object, rhai::EvalAltResult};
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pub(super) fn convert_op<A, B>(from: A) -> Result<B, EvalAltResult>
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where
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B: TryFrom<A>,
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<B as TryFrom<A>>::Error: std::error::Error + Sync + Send + 'static,
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{
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B::try_from(from).map_err(|e| {
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EvalAltResult::ErrorSystem("Data conversion error".to_owned(), Box::new(e))
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})
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}
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/// Generate opcode-generic instruction insert macro
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macro_rules! gen_ins {
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($($($name:ident : $ty:ty),*;)*) => {
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paste::paste! {
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$(
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/// Instruction-generic opcode insertion function
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/// - `obj`: Code object
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/// - `opcode`: opcode, not checked if valid for instruction type
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/// - … for operands
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#[inline]
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pub fn [<$($ty:lower)*>](
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obj: &mut Object,
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opcode: u8,
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$($name: $crate::ins::optypes::$ty),*,
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) -> Result<(), EvalAltResult> {
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// Push opcode
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obj.sections.text.push(opcode);
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// Insert based on type
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$($crate::ins::optypes::insert!(&$name, obj, $ty);)*
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Ok(())
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}
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)*
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/// Generate Rhai opcode-specific instruction insertion functions
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///
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/// `gen_ins_fn!($obj, $opcode, $optype);` where:
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/// - `$obj`: Code object
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/// - `$opcode`: Opcode value
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macro_rules! gen_ins_fn {
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$(
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($obj:expr, $opcode:expr, [<$($ty)*>]) => {
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// Opcode-specific insertion function
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// - Parameters = operands
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move |$($name: $crate::ins::rity::$ty),*| {
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// Invoke generic function
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$crate::ins::generic::[<$($ty:lower)*>](
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&mut *$obj.borrow_mut(),
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$opcode,
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$(
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// Convert to desired type (from Rhai-provided values)
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$crate::ins::generic::convert_op::<
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_,
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$crate::ins::optypes::$ty
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>($name)?
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),*
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)?;
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Ok(())
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}
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};
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// Internal-use: count args
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(@arg_count [<$($ty)*>]) => {
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{ ["", $(stringify!($ty)),*].len() - 1 }
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};
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)*
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// Specialisation for no-operand instructions
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($obj:expr, $opcode:expr, N) => {
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move || {
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$crate::ins::generic::n(&mut *$obj.borrow_mut(), $opcode);
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Ok(())
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}
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};
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// Internal-use specialisation: no-operand instructions
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(@arg_count N) => {
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{ 0 }
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};
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}
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}
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};
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}
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/// Specialisation for no-operand instructions – simply just push opcode
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#[inline]
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pub fn n(obj: &mut Object, opcode: u8) {
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obj.sections.text.push(opcode);
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}
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// Generate opcode-generic instruction inserters
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// (operand identifiers are arbitrary)
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//
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// New instruction types have to be added manually here
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gen_ins! {
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o0: R, o1: R;
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o0: R, o1: R, o2: R;
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o0: R, o1: R, o2: R, o3: R;
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o0: R, o1: R, o2: B;
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o0: R, o1: R, o2: H;
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o0: R, o1: R, o2: W;
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o0: R, o1: R, o2: D;
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o0: R, o1: B;
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o0: R, o1: H;
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o0: R, o1: W;
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o0: R, o1: D;
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o0: R, o1: R, o2: A;
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o0: R, o1: R, o2: A, o3: H;
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o0: R, o1: R, o2: O, o3: H;
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o0: R, o1: R, o2: P, o3: H;
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o0: R, o1: R, o2: O;
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o0: R, o1: R, o2: P;
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o0: O;
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o0: P;
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}
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#[allow(clippy::single_component_path_imports)]
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pub(super) use gen_ins_fn;
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}
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/// Generate instructions from instruction table
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///
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/// ```ignore
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/// instructions!(($module, $obj) {
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/// // Data from instruction table
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/// $opcode, $mnemonic, $opty, $doc;
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/// …
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/// });
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/// ```
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/// - `$module`: Rhai module
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/// - `$obj`: Code object
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macro_rules! instructions {
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(
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($module:expr, $obj:expr $(,)?)
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{ $($opcode:expr, $mnemonic:ident, $ops:tt, $doc:literal;)* }
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) => {{
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let (module, obj) = ($module, $obj);
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$({
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// Object is shared across all functions
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let obj = Rc::clone(&obj);
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// Register newly generated function for each instruction
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FuncRegistration::new(stringify!([<$mnemonic:lower>]))
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.with_namespace(rhai::FnNamespace::Global)
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.set_into_module::<_, { generic::gen_ins_fn!(@arg_count $ops) }, false, _, true, _>(
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module,
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generic::gen_ins_fn!(
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obj,
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$opcode,
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$ops
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)
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);
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})*
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}};
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}
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/// Setup instruction insertors
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pub fn setup(module: &mut Module, obj: Rc<RefCell<Object>>) {
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// Import instructions table and use it for generation
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with_builtin_macros::with_builtin! {
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let $spec = include_from_root!("../hbbytecode/instructions.in") in {
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instructions!((module, obj) { $spec });
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}
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}
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}
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