UMBC CMSC 313, Computer Organization & Assembly Language, Fall 2003

Project 3: External Records

Due:

Objective

Assignment

struct {
char realname[32] ;
char nickname[16] ;
char alignment[20] ;
char role[20] ;
int points ;
int level ;

} records[10] ;

int num_records = 10 ;

Your assembly language program must search through the array and find the record with the least number of points and the record with the alphabetically first nickname. It must then print out the realname field of these two records. E.g.,

Lowest Points: James Pressman
First Nickname: Dan Gannett

Implementation Notes

• The sample data in records.c contains 10 records, but your program should work with any number of records. The number of records is stored in the int variable num_records.
• In order to access the externally defined array and integer variable, you must have the following declaration in your assembly language program:

  extern records, num_records

• You must also make your own test cases. The example in records.c does not fully exercise your program. Your program will be graded based upon other test cases.
• You will need to link your assembly language program with the data defined in the C program:

  gcc -c records.c
  nasm -f elf report.asm
  ld records.o report.o

• An important part of this project is deciding how to use indexed addressing to access the data in the records. Think this through carefully. A clean and logical approach to this problem will yield clean and logical code that is easier to construct and, more importantly, easier to debug.
• Your program should be reasonably robust and report errors encountered (e.g., empty array) rather than crashing.
• Note that the strings stored in the array are C-style null-terminated strings.
• Nicknames should be compared using dictionary ordering. For example, any string starting with the letter 'a' comes before any string that starts with 'b'. In the case that one string is a prefix of another, the shorter string come first. E.g., "egg" comes before "egghead".
• To access each field of the record, you should use an offset from the address of the record. You should use %define constants instead of magic numbers. E.g.,

  %define NickOffset 32
  %define AlignOffset 48
  %define RoleOffset 68
  %define PointsOffset 88
  %define LevelOffset 92
  %define RecSize 96

• Project 4 will be based upon Project 3, so keep in mind that you will need to extend/modify this program.

Turning in your program

Use the UNIX submit command on the GL system to turn in your project. You should submit at least 4 files: your assembly language program, at least 2 of your own test cases and a typescript file of sample runs of your program. The class name for submit is cs313_0101, cs313_0102 or cs313_0103 for respectively sections 0101 (Chang), 0201 (Patel & Bourner) or 0301 (Macneil). The name of the assignment name is proj3. The UNIX command to do this should look something like:

submit cs313_0103 proj3 report.asm myrec1.c myrec2.c typescript