Assignment 4, Solutions

	USE	"hawk.h"

	LIS	R15, 1
	LIS	R14, 2
	ADD	R13, R14, R15
	MOVE	R12, R14
	ADDSI	R12, 2
	ADDI	R11, R14, 3
	LIL 	R10, #FFFFFF
	ADDSI   R10, 7
	ORIS	R9,  7

All of the instructions used here are discussed in Chapter 4 of the notes, and for all of them, the chapter shows both the (somewhat) human readable form of the instructions and the binary, as well as showing the form of the assembly listing when working with these instructions.

a) Assemble this code into memory. Show the contents of memory as a column of 11 16-bit halfwords in hexadecimal, with the address of each halfword written off to the side. (1 point)

Hint: The first entry in this column would be 00: 01DF

Suggestion: As in last week's assignment, do it by hand first, converting the code to binary and then hexadecimal, and then shuffling the pieces into the correct order. Then check your work by assembling this code using the SMAL assembler and then loading the resulting object file into the Hawk emulator to see what data actually lands in memory. (You do not need to link this code.) If you do this both ways, you prove that you understand what the assembler did and you check your work.

        00: 01DF
        02: 02DE
        04: EF3D
        06: FEFC
        08: C21C
        0A: 6EFB
        0C: 0003
        0E: FFEA
        10: FFFF
        12: C71A
        14: 07C9

b) After these instructions are executed, what data registers (R1 through R15) are changed and what are their new values? (1 point)

Suggestion: Do it by hand first! Then check your work by loading the object code in the Hawk emulator and using the s command (single step) to run each of the 9 instructions in succession. If you do it both ways, you will both maximize your learning and be able to check your work.

        R9: 00000007
        RA: 00000006
        RB: 00000005
        RC: 00000004
        RD: 00000003
        RE: 00000002
        RF: 00000001

c) The program above begins with a line saying USE "hawk.h". This causes the assembler to read the file hawk.h, and since that file is not defined in your directory, it looks for it in the hawk library. A copy of that file is available on line, at
-- http://homepage.cs.uiowa.edu/~dwjones/arch/hawk/hawk.txt
Take a look, and see if you can find all of the different macro calls that are executed in order to assemble the third instruction of the file, ADD R13,R14,R15. List the macro calls involved, giving, for each, the name and the values of the parameters. (0.5 points)

ADD R13,R14,R15 is a macro call. This calls qNZREGq R14, qNZREGq R15, and qTHREEREGq #3000,R13,R14,R15.