printnum.h File Reference

Defines interface of printnum.c functions (do not modify) More...

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Functions
char	getDigit (int val)
void	divRem (int numerator, int divisor, int *quotient, int *remainder)
void	printNum (int x, int base)

Variables
char *	digits

Detailed Description

This file defines the interface to a C file printnum.c that you will complete. You will learn how to use the C language operators for address-of (&), and dereferencing pointers *). This will serve as a model when you implement the same functions in LC3 assembly language.

Function Documentation

divRem()

void divRem	(	int	numerator,
		int	divisor,
		int *	quotient,
		int *	remainder
	)

Calculate both the quotient and remainder of a division and return the values via pointers. You may use the C operators for division (/) and modulus (%). However, you might want to write a loop to using repeated subtraction do the calculations to help you understand how you will implement this in LC3 assembly language (which has no operators for division or modulus).

Parameters

numerator	- non-negative value for numerator
divisor	- a positive value to divide by
quotient	- a pointer to the location to store the result of division
remainder	- a pointer to the location to store the remainder

Todo:

Implement based on documentation contained in printnum.h

getDigit()

char getDigit

(

int

val

)

Return the character corresponding to the digit. Use val as an index into the string digits

Parameters

val	- a value in the range of 0 - (base-1)

Returns

- character '0' .. '9' or 'A'..'Z'

Todo:

Implement based on documentation contained in printnum.h

printNum()

void printNum	(	int	x,
		int	base
	)

Print a number in the specified base. Use the C call putchar() to print a single character obtained using getDigit(). This corresponds to the OUT instruction of the LC3 OS. You may not use any other C I/O routine for printing. This function MUST be implemented recursively.

Parameters

x	- the number to print
base	- the base in which the number should be printed

Todo:

Implement based on documentation contained in printnum.h

Variable Documentation

digits

char* digits

A string of characters representing the digits to output for a particular value. Defined in the file testPrint.c.