Assignment 2 Solution

SAL program

# This SAL program checks for the divisibility of the entered 
# integer by 3,4 and 5. The focus of this assignment is on the use of
# procedures with proper error checking and appropriate documentation.

# Data Definitions 


.data


# Return addresses for the procedures indicated by their side

get_int_ra:     .word   # procedure get_int
divisible_ra:   .word   # procedure divisible
print_ra:       .word   # procedure print

int             .word   # entered integer
divisor         .word   # current divisor of integer
min_div:        .word 3 # least value of divisor (for the loop)
max_div:        .word 5 # maximum value of divisor (for the loop)
reminder:       .word   # holds the reminder after division
rflag:          .word   # reminder flag --> 0 indicates divisible
                        #                   1 indicates not divisible

# Some character and string constants to provide nice user interface

newline:        .byte '\n'

enter_str:      .asciiz "\nEnter a positive integer(0 to quit): "
neg_str	:       .asciiz "\nSorry! Try with a +ve integer\n "
bye_str:        .asciiz "\nBye Bye! Hope u enjoyed this \n\n"
div_str:        .asciiz " is evenly divisible by "
ndiv_str:       .asciiz " is not evenly divisible by "

# Code
# This program inputs an integer, prints if it is evenly divisible by
# 3,4 and 5 and repeats until the user enters 0. For negative integers
# an error message is given


.text
__start:

	la get_int_ra,rtn1      # load return address for proc get_int
	b get_int
rtn1:
	blez int,wrong          # go to wrong if the integer is <= 0
	move divisor,min_div    # divisor is initialised to min_div(loop)
divide_loop:
	la divisible_ra,increment       # load retaddr for proc divisible
	b divisible
increment:
	add divisor,divisor,1   # increment divisor
	ble divisor,max_div,divide_loop # if divisor <= max_div loop
	b __start               # go back to the repeat loop
wrong:
	beqz int,end            # check if int = 0 (--> quit)
	puts neg_str            # int is negative
	b __start
end:
	puts bye_str            # end of program
	done

# get_int inputs an integer


get_int:

	puts enter_str
	get int
	b (get_int_ra)

# procedure divisible checks if int is evenly divisible by divisor


divisible:

	move rflag,0                    # initialise rflag to 0
	rem reminder,int,divisor        # reminder= int mod divisor
	beqz reminder,call_print        # if reminder=0 call print proc
	move rflag,1                    # else set rflag and call print
call_print:
	la print_ra,div_ret             # loading return addr for print
	b print
div_ret:
	b (divisible_ra)

# procedure print checks if reminder flag is set or not.
# If reset, it prints evenly divisible
# If set, it prints not divisible


print:

	put newline
	put int
	beqz rflag,print_div		
	puts ndiv_str           # not divisible
	put divisor
	put newline
	b print_ret
print_div:
	puts div_str            # divisible
	put divisor
	put newline
print_ret:
	b (print_ra)

Grading Criteria

For this assignment, Documentation, Error checking and coding style have been taken into account besides a working code. Following is the relative importance of the categories :

 Working program         : 70%
 Good coding style       : 15%
 Proper error checking   : 10%
 Good Documentation      :  5%    

Important piece of information

For this and all future assignments, the first copy that we come across will be graded. So, make sure that you go over your work before handing it in.