CSCI-2500 Computer Organization

Homework 1
Due Date: Sep 25th (received by midnight)

Submission Instructions

This homework involves writing a number of C programs that are used to test how long it takes to perform simple arithmetic operations. You also need to write a C program that can run the unix time command on any of the arithmetic programs, so you can measure how long it takes to run them (and so you get some experience playing with exec()). All code must be in C (no shell scripts please)!

Part 1) individual arithmetic operation test programs

Integer Addition program

Write a program that accepts a single command line argument that specifies the number of integer addition operations that should be done. The program should then perform the specified number of integer addition operations and then exit. No output should be generated by this program. Here is what it might look like to compile and run the program (I called mine iadd.c), including using the unix time command to see how long it takes:

> gcc -o iadd iadd.c
> ./iadd 
ERROR: ./iadd needs a count
> ./iadd 10000
> time ./iadd 10000

real    0m0.011s
user    0m1.003s
sys     0m0.004s

> time ./iadd 100000000

real    0m2.738s
user    0m1.661s
sys     0m0.009s

Multiplication and Floating Point ops

Write 3 similar programs, one that does integer multiplication, one that does floating point addition and one that does floating point multiplication. In all cases, do your best to minimize the code that is not part of the specific arithemtic operations being measured (don't add a lot of other stuff!). I named my programs like this:

• Integer addition: iadd.c
• Integer multiplication: imult.c
• Floating point addition: fadd.c
• Floating point multiplication: fmult.c

All four programs should accept a single command line parameter that indicates the number of operations to be done.

Part 2) Wrapper program

Write a program that does the following:

• Allows the user to select one of the 4 operations:
  • Integer addition
  • Integer multiplication
  • Floating point addition
  • Floating point multiplication
• Allows the user to type in the number of operations desired.
• runs the Unix time command on the proper program

Your wrapper program can either exit once the measurement is made (as will be the case if it calls exec directly) or can continue to prompt the user for another operation/count (to accomplish this you will need to have the wrapper program fork, and then have the child do the exec - the parent can just go back and ask the user for the next test.

> ./hw1
Select desired operation:
 1      Integer addition
 2      Integer multiplication
 3      Floating point addition
 4      Floating point multiplication
1
Enter number of iterations
100000000
Spawning ./iadd 100000000

        2.38 real         2.35 user         0.00 sys
> ./hw1
Select desired operation:
 1      Integer addition
 2      Integer multiplication
 3      Floating point addition
 4      Floating point multiplication
3
Enter number of iterations
100000000
Spawning ./fadd 100000000

        2.69 real         2.69 user         0.00 sys
>

Deliverables

Your submission must include the following:

• Source code for all 5 programs

• A README file that includes a single line description of the contents of each file, the machine type and compiler used to compile/test your code, instructions on how to run your program and anything else you want to tell us.

• A brief writeup that includes the following:

  • A summary of the results of testing each of the operations (perhaps come up with an estimate of the number of operations per second for each of the 4 operations). A table would be nice!

  • A paragraph or 2 describing what happens when you change the operands (does it matter what specific additions are done, or do they all take the same time?).

Submission Instructions

Submission Instructions are here. Please make sure you send submissions to comporg-submit@cs.rpi.edu not to comporg@cs.rpi.edu!!!