Replication of Multiplication game from https://www.mathsisfun.com/games/multiplication-game.html in MIPS Assembly
The program starts in Main.asm. After prompting the player if they want to start a game, the program will ask the player to input two integers from 1-9. For the first time this happens, the player can put any two numbers. But for anytime after, the player must change one of the numbers and keep one of them the same. The program will not let you input numbers that do not follow these rules, and will make you re-input if not followed.
After the player’s turn ends, the computer gets to go. The computer has the same rules as the player and will keep one number the same and one different. It is random which number changes and the number it picks to set as the new number is also random. The numbers the computer played are printed to the console for the player to see.
After each respective turn, the new values are stored into memory and used to find the location in the scoreboard to update, so the program knows who has played where (0 for no one, 1 for the player, and 2 for the computer). The program finds where in the scoreboard to update by going through each possible input and finding its same location on a second gameboard that stores the numbers.
When each turn ends, a segment of instructions checks the scoreboard for the win condition (4 in a row). By finding the addresses to the current row and column of the last played space, the program is able to index through the scoreboard and determine if the win conditions are met. If they are, the game ends and the player is told who won, then the program will end.
If no one is decided as a winner just yet, the program prints out the grid into the console with the same numbers indicating who has played in what spaces, and it becomes the player’s turn again.
One of the most difficult parts of this assignment was learning how to navigate and create a 2D array without explicitly being given a way to do it. I decided to make a 1D array, but simply make each row end after 6 integers to give the illusion of a 2D array. This made it challenging to check if the win condition had been met in a column, but I realized that I could just index the array by 6 integers at a time to immediately jump down a row and be in the same column from wherever the program was indexed to at the time. After implementing this method, all I had to do was track how many consecutive places either the player or computer had scored on, resetting the count if the streak was broken.
Another issue I had was with the input validation. Because there are no easy ways to check if the inputs were in the range 1-9, I had to check if the inputs were <9 and >1 and then used an and gate to determine if both requirements were met. Similar methods were put in place to determine if one number had changed and the other hadn’t, but this time using an xor gate.
Determining the flow of the program also wasn’t easy. To maximize efficiency, I tried to load things from memory the least number of times, making it difficult to keep track of what action the program needed to perform next and what resources it needed. Using conditional branches and jumps in conjunction with keeping necessary resources in registers made the gameplay loop not too difficult to keep track of.