Assignment 3 Solutions

Part of the homework for 22C:60, Fall 2010
by Douglas W. Jones
THE UNIVERSITY OF IOWA Department of Computer Science

  1. Background: A Java, C or C++ programmer could create a table of the squares of the integers from 0 to 8 by writing: 
            int squares[]={0,1,4,9,16,25,36,49,64};

    Assume that integers are 32-bit values and assume that this table is a constant -- that is, that there will be no assignments to squares or to any of the table entries other than this initializer.

    The problem: Write SMAL code equivalent to this. (1 point) 

                    ALIGN   4       ; recommended, no penalty if missing
        SQUARES:                ; may be on same line as first W
                W       0
                W       1       ; entries may be one per line
                W       4       ; or multiple words per line (as below)
                W       9       ; but should not be mixed like this
                W       16,25,36,49,64

  2. Background: Consider maintaining the table of squares as a list, where each item in the list consists of a pointer to the next item in the list and an integer value. The last item in the list has a null pointer in its next tiem field.

    The problem: Write SMAL code to represent a constant list of the first four squares, in ascending order, starting with the square of zero. (1 point) 

            NULL    =       0       ; recommended definition
                ALIGN   4       ; recommended
                                ; Specific label names are not determined
                                ; but some kind of system should be used.
        HEAD:
                W       SQUARE1 ; next
                W       0       ; zero squared
        SQUARE1:
                W       SQUARE2 ; next
                W       1       ; one squared
        SQUARE2:
                W       SQUARE3 ; next
                W       4       ; two squared
        SQUARE3:
                W       NULL    ; next
                W       9       ; three squared

  3. Background: Consider making an array of days of the week. A C programmer could write 
            const char dayname[][]={ "Sunday", "Monday", "Tuesday",
                "Wednesday", "Thursday", "Friday", "Saturday" };

    This is actually a constant array of pointers to null-terminated strings, despite the fact that the declaration looks like a two-dimensional array of characters.

    The problem: Write SMAL code to represent this. (1 point) 

            	ALIGN	4	; recommend
        			; After DAYNAME, label names are not
        			; determined by the assignment but some
                                ; kind of system should be used.
        DAYNAME:
        	W	SUN,MON,TUE,WED,THU,FRI,SAT
        SUN:	ASCII	"Sunday",0
        MON:	ASCII	"Monday",0
        TUE:	ASCII	"Tuesday",0
        WED:	ASCII	"Wednesday",0
        THU:	ASCII	"Thursday",0
        FRI:	ASCII	"Friday",0
        SAT:	ASCII	"Saturday",0