Drawing Lab mips assembly, Im trying to make a drawing lab and I am so unbelieveably confused. Please help with what you can Ill include as much as I can on my end.

#this is what i had for lab $3$

draw$\_$cursor:

push ra

la t$2,$ display$\_$spr$\_$table

move t$0,$ s$0$

# multiply by $8$

sll t$0,$ t$0,3$

sb t$0,0($t$2)$

move t$0,$ s$1$

# multiply by $8$

sll t$0,$ t$0,3$

sb t$0,1($t$2)$

sb zero, $2($t$2)$

li t$0,0$x$41$

sb t$0,3($t$2)$

pop ra

jr ra

This is what I have so far for this method:

#this is what I have so far for lab $4$

draw$\_$cursor:

push ra

la t$2,$ display$\_$spr$\_$table

# get mouse coordinates

lw t$0,$ display$\_$mouse$\_$x

lw t$1$ display$\_$mouse$\_$y

# calculate cursor coordinates

addi t$0,$ t$0,-3$

addi t$1,$ t$1,-3$

sb zero, $2($t$2)$

pop ra

jr ra

This is my prompt for the method

$2.$ draw$\_$cursor $$

Just like lab $3,$ you need to draw a cursor on the screen. Unlike lab $3,$ you$$ll be using the mouse position as the cursor$$s position instead of using your own variables and keyboard arrows to move it$.$

The MMIO variables for the mouse$$s position are described in detail below. Your draw$\_$cursor function will be almost exactly the same as lab $3$s$,$ with a couple changes:

the coordinates will be display$\_$mouse$\_$x $-3$ and display$\_$mouse$\_$y $-3$

the tile number will be CURSOR$\_$TILE instead of $0$

Done right, you should be able to see a crosshair cursor like in the image when you move your mouse over the display, and it should $$stick to$$ your mouse cursor.

Also, when you move your mouse cursor off the display, it should disappear.

I will also attatch the rest of the lab instructions incase that helps: The MMIO variables for the mouse's position are described in detail below. Your

draw$\_$cursor function will be almost exactly the same as lab $3\text{'}$s$,$ with a couple

$21924,4$:$11$ PM

changes:

the coordinates will be

display$\_$mouse$\_$x $-3$ and

display$\_$mouse$\_$y $-3$

the tile number will be CURSOR$\_$TILE

instead of $0$

Done right, you should be able to see a

crosshair cursor like in the image when you

move your mouse over the display, and it

should "stick to$"$ your mouse cursor.

Also, when you move your mouse cursor off the display, it should disappear.

How to get mouse input in the display

There are two variables for getting the mouse position:

display$\_$mouse$\_$x

display$\_$mouse$\_$y

If you Iw from them, you will get the coordinates of the mouse measured from

the top$-$left of the display. Both $x$ and $Y$ range $[0,127].$ However, if the mouse

cursor is outside of the display, both variables will instead be $-1.$ You only

have to check one: either they're both $-1$ or neither is$.$

There is a minor bug that happens when you click and drag on the display,

which allows the display$\_$mouse$\_$x$/$y variables to go outside the range

$0,127$ if you drag the cursor off the edges of the display. I$\text{'}$m not $100\%$ sure

why it happens, but it's easy to work around. Failing to work around it can

cause strange crashes if you aren't careful with what you do with those

invalid coordinates.

For getting the mouse buttons, it works a little differently from keyboard input.

Since there are only three buttons, you can get their state all at once, and use

bitwise AND to extract the state of just one. For example:

$\_$endif$\_$lbutton:

The mouse button variables are:

display$\_$mouse$\_$pressed $-$ to check if a button went from not$-$held to

held this frame $($just pressed it$)$

display$\_$mouse$\_$held $-$ to check if a button is being held down or not

display$\_$mouse$\_$released $-$ to check if a button went from held to not$-$

held this frame $($just let go$)$

And the constants you use in the bitwise AND are:

MOUSE$\_$LBUTTON $-$ left button $($trackpad normal click$)$

MOUSE$\_$RBUTTON $-$ right button $($trackpad two$-$finger click or bottom$-$right

click$)$

MOUSE$\_$MBUTTON $-$ middle button $($scroll wheel click; trackpad three$-$finger

click sometimes$)$

check$\_$input and the drawmode$\_$functions

Although it's called check$\_$input it kinda ends up doing... most stuff. Lol.

$($Hey$,$ there is a "more elegant" way to do this but it ends up being a bunch of

extra complexity for not a lot of benefit in this case.$)$

All my check$\_$input does is essentially switch on the drawmode variable

and based on which value it is$,$ calls one of drawmode$\_$nothing $,$

drawmode$\_$brush, or drawmode$\_$color $.$

You already know enough to do this. You know how to make a switch$-$case,

you know how to call functions, you know how to stub them out. Go do it$.$

But,