Struct lc3_ensemble::asm::SymbolTable

pub struct SymbolTable { /* private fields */ }

The symbol table created in the first assembler pass that encodes source code mappings to memory addresses in the object file.

The symbol table consists of:

• A mapping from source code labels to memory addresses.
• A mapping from source code line numbers to memory addresses (if debug symbols are enabled, see SymbolTable::new).
• The source text (if debug symbols are enabled, see SymbolTable::new).

Here is a table of the mappings that the symbol table provides:

from ↓, to →	label	memory address	source line/span
label	-	SymbolTable::lookup_label	SymbolTable::get_label_source
memory address	SymbolTable::rev_lookup_label	-	SymbolTable::rev_lookup_line
source line	none	SymbolTable::lookup_line	-

Implementations

impl SymbolTable

pub fn new(stmts: &[Stmt], src: Option<&str>) -> Result<Self, AsmErr>

Creates a new symbol table.

This performs the first assembler pass, calculating the memory address of labels at each provided statement.

If a src argument is provided, this also computes debug symbols and includes them within this SymbolTable struct. These debug symbols include:

• Mappings from source code line numbers to memory addresses
• Source code text (and more detailed calculations with source code, see SourceInfo for more details)

pub fn lookup_label(&self, label: &str) -> Option<u16>

Gets the memory address of a given label (if it exists).

pub fn rev_lookup_label(&self, addr: u16) -> Option<&str>

Gets the label at a given memory address (if it exists).

pub fn get_label_source(&self, label: &str) -> Option<Range<usize>>

Gets the source span of a given label (if it exists).

pub fn lookup_line(&self, line: usize) -> Option<u16>

Gets the address of a given source line.

If debug symbols are not enabled, this unconditionally returns None.

pub fn rev_lookup_line(&self, addr: u16) -> Option<usize>

Gets the source line of a given memory address (if it exists.)

The result can be converted into a source span (range of characters encompassed by the instruction) using SymbolTable::source_info and SourceInfo::line_span.

If debug symbols are not enabled, this unconditionally returns None.

pub fn source_info(&self) -> Option<&SourceInfo>

Reads the source info from this symbol table (if debug symbols are enabled).

pub fn label_iter(&self) -> impl Iterator<Item = (&str, u16)> + '_

Gets an iterable of the mapping from labels to addresses.

Trait Implementations

impl Debug for SymbolTable

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.