Your task is to write a program which computes an initial portion of a generalized Fibonacci sequence and prints it out. You will write this program in MIPS using the MARS simulator.
Preliminaries
Click on the assignment link.
Once you have accepted the assignment, you can clone the repository on your computer by following the instruction and begin working.
Be sure to ask any questions on Ed.
Program specification
No starter code is provided this time. Create a file in MARS called lab3.asm and create your program there. You may wish to look at your code for Lab 1 for reference.
Read three input values from the keyboard:
- the first number in the sequence,
- the second number in the sequence, and
- the number of elements of the sequence.
Each element of the sequence (beyond the first two) is equal to the sum of the previous two. For example, if the user inputs 3, 1, and 10, then your program should generate the sequence 3, 1, 4, 5, 9, 14, 23, 37, 60, 97.
Output
For each element of the sequence that you generate, display
- the number in decimal notation (using system call 1),
- the number in hexadecimal, and
- the number of 1-bits in the binary representation of the number.
For the example above, you would display the following.
3 0x00000003 2
1 0x00000001 1
4 0x00000004 1
5 0x00000005 2
9 0x00000009 2
14 0x0000000E 3
23 0x00000017 4
37 0x00000025 3
60 0x0000003C 4
97 0x00000061 3
The hex version can be displayed using system call 34.
Implementation
To get full credit for this assignment, you will need to create a function to count the number of ones in a number. You should use proper calling conventions as discussed in class. You will also need to use a loop to generate the generalized Fibonacci numbers.
You will not need to use either arrays or recursion for this problem. You are required to write a separate function which counts the number of ones in a number. (Hint: Think about using bit operations to isolate each bit in the number, and add them together.)
Make sure to document your programs thoroughly. (This is especially important in assembly language programs, since the code itself is less easily read than high-level language code.) This should include:
- A block of comment lines at the beginning of the source file, giving the name and author of the program and a black-box description of what it does.
- A few comment lines between major sections of the program, describing the contents of each section.
- A comment at the end of most source lines, describing what the instruction on that line does.
Hints
- Write a program that does this in a high-level language and then translate it to MIPS. It will be a lot easier to solve this problem if you figure out the logic first and write the assembly for it second.
- Syscall 35 will print an integer in binary.
- To count the ones in a number, think about using bit operations to isolate each bit of the number and then add the bits together. A loop and bit shifting instructions will be helpful here.
- Printing the string
\t (the tab character) between each number will give you the nice even spacing shown in the example. Likewise, printing the string \n will give you a newline.
Helpful resources
- A guide to the MARS simulator
- A list of MIPS system calls
Submission
Submit the lab by committing your code and pushing it to your GitHub repository.