util.h File Reference

utility functions for LC3 assembler More...

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Data Structures
struct	name_val

Typedefs
typedef struct name_val	name_val_t

Functions
name_val_t *	util_bin_search (name_val_t map[], int numNames, const char *name)
int	util_get_opcode (const char *name)
int	util_is_valid_label (const char *s)
int	util_get_reg (const char *regStr)
int	util_parse_cond (const char *condCodeStr)

Detailed Description

This defines the interface to some utilities for the LC3 assembler. In completing the corresponding .c file, you will learn how to encode information in data structures, rather than directly in "code". You will also learn how to do some simple character processing.

Author

Fritz Sieker

Typedef Documentation

typedef struct name_val name_val_t

Define a mapping between a name and an integer value

Function Documentation

name_val_t* util_bin_search	(	name_val_t	map[],
		int	numNames,
		const char *	name
	)

Search a sorted list of items for a given name. The names are case insensitive, so the name "foo" and "Foo" match. This function is only used in util.c, but is declared here for documentation purposes.

Parameters

map	- a sorted array of values
numNames	- number of entries in the array
name	- the name to search for (case insensitive)

Returns

NULL if the name is not in the list, or a pointer to the name/value pair.

Todo:

implement this function

int util_get_opcode

(

const char *

name

)

Get the opcode associated with an LC3 op (e.g. "ADD")

Parameters

name	- name of operand

Returns

the opcode for this name, or -1 if the name is not and LC3 operation information about that instruction

int util_get_reg

(

const char *

regStr

)

Determine if the string represents a valid register specification A register is specified by the letter 'R' (case insesitive) followed by a digit 0 to 7.

Parameters

regStr

- the string to check

Returns

the register number if the string is a valid register, or -1 if it is not.

int util_is_valid_label

(

const char *

s

)

Determine if a string is a valid label or not. Valid labels beging with a letter or '_' and may contain only letters, digits and ('_'). You may find the C header ctype.h useful.

Parameters

s	- ths string to validate @ return 0 if the string is not valid, non-zero if it is

Todo:

implement this function

int util_parse_cond

(

const char *

condCodeStr

)

Determine the condition code associated with the string. The string consists of of 0 to 3 three characters, with no more that one each character from the set 'nzp' (case insensitive). The values must follow that order. That is, if 'n' is present it MUST proceed 'z' and/or 'p'. If 'z' is present, in must preceed 'p'.

Parameters

condCodeStr

- the string to parse (e.g. "zp")

Returns

- the value (1-7) representing the condition code or -1 if the condCodeStr is not valid.