assembler.c File Reference

You will modify this file and implement the assembler.h interface. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <stdarg.h>
#include <assert.h>
#include "assembler.h"
#include "lc3.h"
#include "symbol.h"
#include "tokens.h"
#include "util.h"

Functions
line_info_t *	asm_init_line_info (line_info_t *info, const char *opTok)
void	asm_print_line_info (line_info_t *info)
void	asm_error (const char *msg,...)
void	asm_init (void)
line_info_t *	asm_pass_one (const char *asm_file_name, const char *sym_file_name)
void	asm_pass_two (const char *obj_file_name, line_info_t *list)
void	asm_term (line_info_t *list)

Variables
static int	srcLineNum
static int	currAddr

Detailed Description

This is a implementation of the interface that you will write for the assignment. Although there are only four functions defined by the interface, it is likely that you will add many helper functions to perform specific tasks.

Author

your name here

Function Documentation

void asm_error	(	const char *	msg,
			...
	)

A function to print error messages. This function takes a minimum of one parameter. It is exaclty like the printf() function. The first parameter is a formatting string. This will be one of the values defined above that starts with ERR_.The remaining parameters (if any) are the actual values to be printed (generally a token). The function prints the word ERROR: and the the value of srcLineNum along with the information provided by the parameters. It must be used for reporting all errors. After printing the error, the global variable numErrors is incremented. This function relies on the static variable srcLineNum in assembler.c. Suppose one wanted to report that a file could not be opened for reading. The C code might look line this.

FIlE* f = fopen(filename, "r");
if (f == NULL) {
  asm_error(ERR_OPEN_READ, filename);
  // any other actions 
}

Ideally, this function would throw an exception.

Parameters

msg	- the formating string (one of the ERR_xxx macros)
...	- a list of values to be substitued into the format string.

void asm_init

(

void

)

Todo:

implement this function

line_info_t* asm_init_line_info	(	line_info_t *	info,
		const char *	opTok
	)

A function to initialize all the fields of the structure to default values. Since C does not have constructors, it is convenient to write functions to initialize fields of a structure to default values. The first parameter allows the function to be used in two ways. If its value is NULL, the structure is malloc()-ed. If it is not NULL, the structure pointed to by the parameter is initialized. This allow the easy initialization of a local variabe in some other function by passing its address. The fields info->lineNum and info->address are initialized from global values defined in assembler.c. You may modify this function to do additional checks and initialization if you find that usefull. You may not change its signature. This function is only used in assembler.c and should be static. It is declared here for documentation purposes.

Parameters

info	pointer to an existing structure or NULL
opTok	the string representing the operation (e.g. "ADD"

Returns

a pointer to the initialized structure

line_info_t* asm_pass_one	(	const char *	asm_file_name,
		const char *	sym_file_name
	)

Todo:

implement this function

void asm_pass_two	(	const char *	obj_file_name,
		line_info_t *	list
	)

Todo:

implement this function

void asm_print_line_info

(

line_info_t *

info

)

A function to print the infomation extracted from a source line. This is used for debugging only.

Parameters

info	- pointer to informaton about a source line

void asm_term

(

line_info_t *

list

)

Todo:

implement this function

Variable Documentation

int currAddr

static

Global variable containing the current LC3 address

int srcLineNum

static

Global variable containing the current line number in the source file