forked from AbleOS/ableos
95 lines
2.1 KiB
Rust
95 lines
2.1 KiB
Rust
//! Code object
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use {rhai::ImmutableString, std::collections::HashMap};
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/// Section tabel
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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pub enum Section {
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Text,
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Data,
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}
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/// Symbol entry (in what section, where)
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#[derive(Clone, Copy, Debug)]
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pub struct SymbolEntry {
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pub location: Section,
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pub offset: usize,
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}
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/// Relocation table key
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#[derive(Clone, Debug)]
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pub enum RelocKey {
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/// Direct reference
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Symbol(usize),
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/// Indirect reference
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Label(ImmutableString),
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}
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/// Relocation type
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#[derive(Clone, Copy, Debug)]
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pub enum RelocType {
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Rel32,
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Rel16,
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Abs64,
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}
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/// Relocation table entry
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#[derive(Clone, Debug)]
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pub struct RelocEntry {
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pub key: RelocKey,
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pub ty: RelocType,
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}
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/// Object code
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#[derive(Clone, Debug, Default)]
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pub struct Sections {
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pub text: Vec<u8>,
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pub data: Vec<u8>,
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}
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/// Object
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#[derive(Clone, Debug, Default)]
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pub struct Object {
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/// Vectors with sections
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pub sections: Sections,
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/// Symbol table
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pub symbols: Vec<Option<SymbolEntry>>,
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/// Labels to symbols table
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pub labels: HashMap<ImmutableString, usize>,
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/// Relocation table
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pub relocs: HashMap<usize, RelocEntry>,
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}
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#[derive(Clone, Copy, Debug)]
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#[repr(transparent)]
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pub struct SymbolRef(pub usize);
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impl Object {
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/// Insert symbol at current location in specified section
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pub fn symbol(&mut self, section: Section) -> SymbolRef {
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let section_buf = match section {
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Section::Text => &mut self.sections.text,
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Section::Data => &mut self.sections.data,
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};
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self.symbols.push(Some(SymbolEntry {
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location: section,
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offset: section_buf.len(),
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}));
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SymbolRef(self.symbols.len() - 1)
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}
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/// Insert to relocation table and write zeroes to code
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pub fn relocation(&mut self, key: RelocKey, ty: RelocType) {
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self.relocs
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.insert(self.sections.text.len(), RelocEntry { key, ty });
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self.sections.text.extend(match ty {
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RelocType::Rel32 => &[0_u8; 4] as &[u8],
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RelocType::Rel16 => &[0; 2],
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RelocType::Abs64 => &[0; 8],
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});
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}
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}
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