/*

• symbol_table.h
• Declaration of the symbol table API used by the assembler. The
• symbol table maps symbol names to addresses and attributes (code,
• data, external, entry) and provides lookup and update utilities. */

#ifndef SYMBOL_TABLE_H #define SYMBOL_TABLE_H

#include <stddef.h>

/* Maximum length of a label (not including terminating NUL). The

• project specification limits labels to up to 31 characters. */ #define MAX_LABEL_LEN 31

/* Attribute bitmasks for symbols. Symbols may have multiple

• attributes combined with bitwise OR. */ #define ATTR_CODE 0x1 #define ATTR_DATA 0x2 #define ATTR_EXTERN 0x4 #define ATTR_ENTRY 0x8

/* Representation of a single symbol in the table. The name

• contains the label name, address holds the offset (relative to
• start of code) where the symbol is defined and attributes holds
• bitflags describing whether the symbol refers to code/data and
• whether it is external or an entry. */ typedef struct Symbol { char name[MAX_LABEL_LEN + 1]; int address; int attributes; struct Symbol *next; } Symbol;

/* Symbol table structure implemented as a singly linked list. */ typedef struct { Symbol *head; Symbol *tail; } SymbolTable;

/* Initialise an empty symbol table. */ void st_init(SymbolTable *table);

/* Free all symbols and clear the table. */ void st_free(SymbolTable *table);

/* Add a new symbol to the table. Returns 0 on success or 1 if a

• symbol with the same name already exists. */ int st_add(SymbolTable *table, const char *name, int address, int attributes);

/* Find a symbol in the table by name. Returns a pointer to the

• symbol or NULL if not found. */ Symbol *st_find(const SymbolTable *table, const char *name);

/* Update all data symbols by adding an offset to their addresses.

• Returns the number of symbols updated. */ int st_update_data_addresses(SymbolTable *table, int offset);

#endif /* SYMBOL_TABLE_H */