Introduction to RISC-V Assembly Programming

Code due Tue Sep 10th by 11:59pm in your Lab02 GitHub repo

Exam problems due Wed Sep 11th by 11:59pm in your Lab02 GitHub repo

Links

Tests: https://github.com/USF-CS315-F24/tests

Autograder: https://github.com/phpeterson-usf/autograder

GDB Setup for Assembly Debugging

On the BeagleV machines, you can a gdbinit file to get a nice UI for assembly language debugging. The file should be in ~/.config/gdb/gdbinit. If you don’t have a ~/.config you will have to create it. If you don’t have ~/.config/gdb you will have to create it. You can use mkdir -p to create everything at once:

$ cd
$ mkdir -p ~/.config/gdb
$ cd .config/gdb
$ cat > gdbinit
set auto-load safe-path /
set debuginfod enabled off
tui new-layout asm {-horizontal src 1 regs 1} 2 status 0 cmd 1
tui enable
layout asm
^d

Note ^d means type CTRL-d to close the file.

See GDB Usage for links to GDB tutorials.

Requirements

1. You will develop RISC-V assembly language implementations of the following arithmetic problems. You will be given the C implementations, you need to write the RISC-V implementations.
2. Your executable must be compiled with a Makefile
3. Before you add files to your repo, do a $ make clean so you don’t add/commit build products like executables or .o files
4. We will test the labs using autograder

add4: Adds four 32-bit integers together and returns the result. Example:

$ ./add4 1 2 3 4
C: 10
Asm: 10

quadratic: Runs the quadratic equation (ax^2 + bx + c) on the 32-bit integers x, a, b, c and returns the result. Example:

$ ./quadratic 4 3 2 1
C: 57
Asm: 57

min: Calculates the smaller of two 32-bit integers and returns its value. Example:

$ ./min 2 3
C: 2
Asm: 2

sum_array Sums the integer values in an array.

$ ./sumarr 1 2 3 4 5
C: 15
Asm: 15

Given

The Lab02 GitHub repo will contain starter code including a Makefile, the C versions of the functions above, and empty .s files for you to fill in.

Exam-like Problems

Put the solutions to the following problem in a file called problems.pdf in your Lab02 GitHub Repo. You can typeset your solutions or you can write your solutions by hand and scan or take a photo of your work. Just be sure to put your solution in a single file called problems.pdf.

Question 1 - Hex to Decimal

Convert the hexadecimal number 0x3FA to decimal. Show your work.

Question 2 - Binary to Decimal

Convert the binary number 0b10110 to decimal. Show your work.

Question 3 - Decimal to Binary

Convert the decimal number 231 to binary. Show your work.

Question 4 - Bad string_to_int()

Consider the following incorrect implementation of string_to_int():

int string_to_int(char *s) {
    int result = 0;
    for (int i = 0; s[i] != '\0'; i++) {
        result = result * 10 + s[i];
    }
    return result;
}

This function is supposed to convert a string of digits into an integer. However, it does not work as expected. Identify and explain the problem with this code. Show the corrected version.

Rubric

1. Your lab will receive the score indicated by the autograder
2. To get the test cases, git pull in the tests repo