symbol.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "error.h"
#include "parse.h"
#include "symbol.h"

struct symbol_hash symbol_hash[HASH_SIZE];

int ram_address = 16;
int rom_address = 0;

void inc_rom_address()
{
	++rom_address;
}

int get_rom_address()
{
	return rom_address;
}

int get_ram_address()
{
	return ram_address;
}

void print_hash()
{
	int i = 0;
	printf("---------- HASH TABLE ----------\n");
	printf("Position\tAdd\tName\n");
	while(i < HASH_SIZE)
	{
		if(symbol_hash[i].name[0] != '\0')
		{
			printf("HASH: %d\t%d\t%s\n", i, symbol_hash[i].address, symbol_hash[i].name);
		}
		++i;
	}
}

int hash(char symbol[])
{
	int hash = 0;
	int i = 0;
	while(symbol[i] != '\0')
	{
		hash += symbol[i];
		++i;
	}
	hash = hash % HASH_SIZE;
	return hash;
}

int add_entry(char symbol[], int address)
{
	int hash_val;
	hash_val = hash(symbol);
	if(symbol_hash[hash_val].name[0] == '\0') /* no entry at this location yet */
	{
		strcpy(symbol_hash[hash_val].name, symbol);
		if(address < 0)
		{
			symbol_hash[hash_val].address = ram_address++;
		} else {
			symbol_hash[hash_val].address = address;
		}
		return 1;
	} else { /* hash alreay used */

		/* compare value of symbol here with input of function */
		/* this could be a repeat hash */
		if(strcmp(symbol_hash[hash_val].name, symbol) == 0) { return 1; }

		if(next_hash_space() != -1)
		{
			strcpy(symbol_hash[hash_val].name, symbol);
			if(address < 0)
			{
				symbol_hash[hash_val].address = ram_address++;
			} else {
				symbol_hash[hash_val].address = address;
			}
			return 1;
		} else {
			print_hash();
			int i = find_line_num();
			line_notification(i);
			exit_error(13, "Symbol table full");
		}
	}
	return 0;
}

int next_hash_space()
{
	int i = -1;
	do
	{
		++i;
	} while (symbol_hash[i].name[0] != '\0' && i < HASH_SIZE);

	if(symbol_hash[i].name[0] == '\0')
	{
		return i;
	} else {
		return -1;
	}
}

int get_address(char symbol[])
{
	int hash_val, i = 0, j = 0;
	hash_val = hash(symbol);
	if(symbol_hash[hash_val].name != NULL)
	{
		return symbol_hash[hash_val].address;
	} else {
		/*
		could not find hash -- loop through strings
		for length of symbol_hash looking for a match
		*/
		while(strcmp(symbol_hash[i].name, symbol) != 0 && j < HASH_SIZE)
		{
			if(i == HASH_SIZE){ i = 0; } else { ++i; }
			++j;
		}
		if(strcmp(symbol_hash[i].name, symbol) == 0)
		{
			return symbol_hash[i].address;
		}
	}
	return -1;
}