Description
Introduction to MIPS’ Minesweeper
From (Wikipedia), Microsoft Minesweeper (formerly Minesweeper) is a minesweeper computer
game created by Curt Johnson, originally for OS/2, and ported to Microsoft Windows by Robert
Donner, both Microsoft employees at the time. First officially released as part of the Microsoft
Entertainment Pack 1 in 1990, it was included in the standard install of Windows 3.1 in 1992,
replacing Reversi from Windows 3.0. Microsoft Minesweeper has been included without a major
change in all subsequent Windows releases until Windows Vista, at which time an updated version
by Oberon Media replaced it. In Windows 8 and later the game is not included, but Microsoft
Studios published an updated version of it, developed by Arkadium, on Windows Store.
For this project, we will use our own Minesweeper hardware. This tool can be found in minesweeper.zip
located in the CourseWeb under this project. Extract all files to your […]/mars4 5/mars/tools
directory. If you extract all files to the right directory, when you run the MARS program, you should
see “Minesweeper (Memory) V0.1” under the “Tools” menu. Our MIPS’ Minesweeper hardware is
shown below:
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For our Minesweeper hardware, there are three sizes:
• 8 × 8 with 10 mines,
• 12 × 12 with 15 mines, and
• 16 × 16 with 20 mines.
Note that this Minesweeper hardware is just a display/interface. Your program is the one who control its behavior. For example, if you press the ”Reset” button. It does not actually do anything.
It just sends a signal to your program that the ”Reset” button is pressed. Your program needs to
actually reset it.
A MIPS assembly program can control this Minesweeper hardware by writing data onto the main
memory starting at the address 0xFFFF8000. Just imagine that this address (0xFFFF8000) contains a two-dimensional array of bytes. Each byte simply control a cell (row, column) of the
Minesweeper game. For example, for the 8 × 8 game, cell (0, 0), row 0 column 0, is associated with
the memory address 0xFFFF8000, cell (0, 1), row 0 column 1, is associated with the memory address
0xFFFF8001, cell (1, 0), row 1 column 0, is associated with the memory address 0xFFFF8008, and
so on. Note that for a 16×16 game, cell (1, 0) is associated with the memory address 0xFFFF8010.
In other word, the memory location associated with a cell (row, column) is based on the size of the
game.
To change the appearance of each cell on the Minesweeper hardware, simply store a byte data into
the address associated with the cell as follows:
• 0x00: Close
• 0x01: The number 1
• 0x02: The number 2
• 0x03: The number 3
• 0x04: The number 4
• 0x05: The number 5
• 0x06: The number 6
• 0x07: The number 7
• 0x08: The number 8
• 0x09: Blank (nothing is there)
• 0x0A: The mine
• 0x0B: The mine with red X
• 0x0C: The flag
• 0x0D: Exploaded mine
The following is an example of the 8 × 8 board where 0xFFFF8000 is set to 0, 0xFFFF8001 is set
to 1, , 0xFFFF8002 is set to 2, and so on until 0xFFFF800D is set to 13.
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The following program is used to create the output as shown above:
.text
la $s0, 0xffff8000 # Set $s0 to the address of the Minesweeper board
add $s1, $zero, $zero # Counter
addi $s2, $zero, 14 # Upper Bound
loop: beq $s1, $s2, done # Check whether the counter reaches the upper bound
sb $s1, 0($s0) # Store counter (0 – 12) to the address
addi $s1, $s1, 1 # Increase the counter by 1
addi $s0, $s0, 1 # Increase the address by 1
j loop # Go back to loop
done: addi $v0, $zero, 10 # Syscalll 10: Terminate the program
syscall # Terminate the program
Your MIPS assembly program can also receive an input from the Minesweeper hardware as well.
If a user click on the game, change the size, or click the ”Reset” button, the value in the register
$t9 wil l be changed. Note that you must set $t9 to 0 first. Otherwise, the Minesweeper will
not change the value of $t9. In other words, the structure of your program should look like the
following:
.text
# Initialize the game
:
add $t9, $zero, $zero # Ready to receive an input, set $t9 to 0
wait:
beq $t9, $zero, wait # Wait for $t9 to change to nonzero
:
# Process the user input
:
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add $t9, $zero, $zero # Ready to receive an input, set $t9 to 0
j wait
The register $t9 will contain a value associated with the user input as follows:
• Reset: 0x40MMNRNC where
– MM is an 8-bit unsigned number representing the number of mines
– NR is an 8-bit unsigned number representing the number of rows
– NC is an 8-bit unsigned number representing the number of columns
Note that the lower 24-bit in this format is also used in the size selector
• 8 × 8 (10 Mines): 0x200A0808
• 12 × 12 (15 Mines): 0x200F0C0C
• 16 × 16 (20 Mines): 0x20141010
• Left click: 0x8000RRCC where
– RR is an 8-bit unsigned number representing the click row number
– CC is an 8-bit unsigned number representing the click row number
• Right click: 0x8800RRCC where RR and CC are the same as in Left click
What To Do?
The main goal is to write the MIPS assembly program to drive this Minesweeper game so that it
behaves like an actual Minesweeper game. The actual game play will be for the next project. So,
for this one, we will only focus on the initializing part of the game.
Note that the Minesweeper hardware is just an interface/display. You need to maintain another
two-dimensional array of bytes to store what would be at a specific cell. For simplicity of our
discussion, let’s call this array board. Note that inside a computer memory, a two-dimensional
array is simply a one-dimensional array. So, since the largest Minesweeper hardware is 16 × 16,
you should allocate this array board as follows:
.data
board .space 256
Now, you actually have two Minesweeper, at 0xFFFF8000 is the Minesweeper hardware to display/receive input and at the address referred by board to store value of each cell. For simplicity,
you may need a function that copy everything from board to 0xFFFF8000 for debugging purpose.
Part I: Randomly Place Mines (30 Points)
For this part, simply randomly place mines onto the board array. You can assume that the initial
size is always 8 × 8 with 10 mines. If a cell at row r column c has no mine, simply set the value
at board[r][c] to 0. Next, copy data from the array board to 0xFFFF8000 to see the result and
wait for input from user (set $t9 to 0 and wait until $t9 is changed to non-zero value). If a user
change the board size or press the ”Reset” button, your program you starts over and randomly
place mines on the array board and display (copy) again.
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Part II: Initialize Cells (40 Points)
A number in the Minesweeper game represents the number of mines around that cell. For this
part, open all cells of the Minesweeper game. If a cell contains a mine, set its associated memory
location to 10. If a cell contains no mine and there is no mines around it, set its associated memory
location to 9 (blank). If a cell contains no mine and there are one or more mines around it, set its
associated memory location to the number of mines around that cell. Here are some examples:
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Again, if a user click the ”Reset” button or change the size, your program should randomly place
mines, initialize all cells, and display the result on the Minesweeper hardware.
Part III: Mouse Click (30 Points)
For this part, we are going to check whether your program can read mouse inputs. From Part II,
after display the whole board, wait for an input from a user. If a user left-click at row r column
c on the board, your program should display the location (r, c) that the user click as well as
what is at that cell. For example, if a user left-click at row 5 column 3 that contains a mine, your
program should print the following string on the console screen:
Left-Click at row 5 column 3: Mine
If a user right-click at row 2 column 6, and it contains a number 3, your program should display
the following string
Right-Click at row 2 column 6: 3
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If a user left-click at row 0 column 5, and it contains a number nothing, your program should
display the following string
Right-Click at row 0 column 5: Nothing
Submission
The due date of this project is stated on the CourseWeb. Late submissions will not be accepted.
You should submit the file minesweeper init.asm via CourseWeb.
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