CSCI 2321 (Principles of Computer Design), Spring 2014:
Homework 2

Credit:

50 points.

Reading

Be sure you have read all assigned sections of Chapter 2 and Appendix A.

Problems

Do the following problems. You may write out your answers by hand or using a word processor or other program, but please submit hard copy, either in class or in my mailbox in the department office.

1. (5 points) Do problems 2.9 and 2.10 from the textbook.

2. (5 points) Do problems 2.14 and 2.15 from the textbook.

3. (5 points) Do problems 2.19.1, 2.19.2, and 2.19.3 from the textbook. One of the instructions doesn't really make sense. Which one, and why not? (Correction: There are actually two instructions that don't make sense.)

4. (5 points) Do problem 2.27 from the textbook.

5. (5 points) Do problem 2.29 from the textbook.

6. (10 points) Do problem 2.31 from the textbook, omitting the part of the problem that asks you to count instructions. (I.e., just provide the MIPS code.)

7. (10 points) Show what would be produced by linking two object files described by the following tables, producing something analogous to the answer to the worked example on pp. 127ff -- i.e., show the result of everything the linker must do). Assume that the following sizes:
   • For procedure A, a text size of 0x140 and a data size of 0x40.
   • For procedure B, a text size of 0x300 and a data size of 0x50.
   and assume the overall layout shown in the figure on p. 104.

   Table for procedure A:

   Text Segment	Address	Instruction
   	0	lui $at, 0
   	4	ori $a0, $at, 0
   	...	...
   	0x84	jr $ra
   	...	...
   Data Segment	Address	Label
   	0	(X)
   	...	...
   Relocation Info	Address	Instruction Type	Dependency
   	0	lui	X
   	4	ori	X
   Symbol	Address	Symbol
   	...	X

   Table for procedure B:

   Text Segment	Address	Instruction
   	0	sw $a0, 0($gp)
   	4	jmp 0
   	...	...
   	0x180	jal 0
   	...	...
   Data Segment	Address	Label
   	0	(Y)
   	...	...
   Relocation Info	Address	Instruction Type	Dependency
   	0	sw	Y
   	4	jmp	FOO
   	0x180	jal	A
   Symbol	Address	Symbol
   	...	Y
   	0x180	FOO
   	...	A

Programming Problems

Do the following programming problems. You will end up with at least one code file per problem. Submit your program source (and any other needed files) by sending mail to bmassing@cs.trinity.edu, with each file as an attachment. Please use a subject line that mentions the course number and the assignment (e.g., ``csci 2321 homework 2''). You can develop your programs on any system that provides the needed functionality, but I will test them using the SPIM simulator on one of the department's Linux machines, so you should probably make sure they work in that environment before turning them in.

1. (5 points) Add code to your solution to problem 2.27 to make it a complete program that prompts for values for a and b and prints the ending value of a. (Make up some data you think is interesting for array D.) Programs echo.s and echoint.s on the sample programs page show how to input and output text and integer values.

   Correction: Printing the ending value of a is not useful since it doesn't change, and making up interesting data for D is also not useful since the program only writes values to it. I will give full credit, however, for a correct solution to the problem as stated. More useful would be to print all of D after the program computes two loops -- i.e., have the program do the equivalent of the C code
   

       for (k=0; k<(4*b); k++)
           printf("%d\n", D[k]);
   

   You can get up to 2.5 extra-credit points for having your program print D rather than a.

2. (Optional: Up to 10 extra-credit points.) First do problem 2.37 from the textbook, but using the condition that the input ASCII string is meant to represent a positive hexadecimal integer (so for example ``1234'' and ``5A'' are valid inputs, but ``hello'' is not, nor is ``-1''). Then add code to the resulting function so that the result is a complete MIPS program that prompts for an input string, converts it to an integer using your function, and prints the result (in base 10). Programs echo.s and echoint.s on the sample programs page show how to input and output text and integer values.