((code
  (label main
    ; Open screen
    ; use load immediate because it is a pointer to a string, not a value
    (load-immediate $0 &screen-namespace)
    (load-immediate $1 0)
    (syscall OPEN $0 $1)
    ; draw to the device because otherwise the screen wont open
    (syscall WRITE $0 $0 $0)

    (load-immediate $16 &mouse-namespace)
	  (load-immediate $3 12) ; malloc sizeof mouse data
	  (malloc $4 $3)

    (label draw-loop
      ; load mouse click data
	  	(syscall READ $16 $2 $3 $4)
      (load-immediate $5 4) ; offset for x
      (add-nat $6 $5 $2)
      (load-r $7 $6) ; load x
      (load-immediate $5 8) ; offset for y
      (add-nat $6 $5 $2)
      (load-r $8 $6) ; load y
      (load-immediate $5 12) ; offset for btn1
      (add-nat $6 $5 $2)
      (load-r8 $9 $6) ; load btn1 pressed
      (load-immediate $5 13) ; offset for btn2
      (add-nat $6 $5 $2)
      (load-r8 $10 $6) ; load btn2 pressed

      ; first row
      (load $1 &BLACK)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (call &draw-outlined-swatch)

      (load $1 &WHITE)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (call &draw-outlined-swatch)

      ; row 2
      (load $1 &CHARCOAL)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (call &draw-outlined-swatch)

      (load $1 &DARK-GRAY)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (call &draw-outlined-swatch)

      ; row 3
      (load $1 &RED)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (load-immediate $1 41)
      (push $1)
      (call &draw-outlined-swatch)

      (load $1 &ORANGE)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (load-immediate $1 41)
      (push $1)
      (call &draw-outlined-swatch)

      ; row 3
      (load $1 &YELLOW)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (load-immediate $1 61)
      (push $1)
      (call &draw-outlined-swatch)

      (load $1 &GREEN)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (load-immediate $1 61)
      (push $1)
      (call &draw-outlined-swatch)

      ; row 4
      (load $1 &BLUE)
      (push $1)
      (load-immediate $1 1)
      (push $1)
      (load-immediate $1 81)
      (push $1)
      (call &draw-outlined-swatch)

      (load $1 &PURPLE)
      (push $1)
      (load-immediate $1 21)
      (push $1)
      (load-immediate $1 81)
      (push $1)
      (call &draw-outlined-swatch)

      (syscall WRITE $0 $0 $0)
      (jump-eq-nat &draw-loop $9 $11)

      ; if click on box then switch color

      ; else draw the pixel

      (jump-eq-nat &draw-loop $10 $11))

    ; Flush and halt
    (halt))

  (label draw-outlined-swatch
    (pop $3)   ; y
    (pop $2)   ; x
    (pop $1)   ; color

    ; Constants
    (load $4 &GRAY)
    (load-immediate $5 20)       ; outline size
    (load-immediate $6 17)       ; fill size
    (load-immediate $7 2)        ; offset

    (push $4)      ; color (gray)
    (push $2)      ; x
    (push $3)      ; y
    (push $5)      ; width (20)
    (push $5)      ; height (20)
    (call &draw-box)

    (add-int $8 $2 $7)   ; x + 2
    (add-int $9 $3 $7)   ; y + 2

    (push $1)      ; color (original)
    (push $8)      ; x + 2
    (push $9)      ; y + 2
    (push $6)      ; width (17)
    (push $6)      ; height (17)
    (call &draw-box)

    (return))

  ; draw-box(color, x, y)
  ; Pops: y, x, color
  (label draw-box
    ; Pop arguments (reverse order)
    (pop $14)        ; height
    (pop $12)        ; width
    (pop $13)        ; y_start
    (pop $11)        ; x_start
    (pop $3)         ; color

    ;; get the screen width dynamically from the device
    (load-immediate $0 &screen-namespace)
    (load-immediate $16 1) ; device info call
    (load-immediate $17 16) ; sizeof screen device info
    (malloc $18 $17)
    (syscall IOCTL $0 $16 $18)
    (load-immediate $1 12) ; offset for width
    (add-nat $19 $18 $1)
    (load-r $2 $19) ; load width
    (load-immediate $1 4) ; offset for width
    (add-nat $19 $18 $1)
    (load-r $21 $19) ; load base pointer
    (add-nat $21 $21 $1) ; need to add offset for fat pointer size

    ; Constants
    (load-immediate $1 1)        ; increment

    ; Compute start address: base + y*640 + x
    (mul-int $15 $13 $2)         ; $15 = y * 640
    (add-int $15 $15 $11)        ; $15 += x
    (add-nat $15 $21 $15)       ; $15 = base + pixel_offset
    (register-move $4 $15)

    ; Outer loop: height times
    (register-move $5 $14)       ; $5 = row counter

    (label draw-box-outer
      (add-int $6 $4 $12)        ; $6 = row end = current + width
      (register-move $7 $4)      ; $7 = pixel pointer

      (label draw-box-inner
        (store-8 $7 $3)          ; write color
        (add-int $7 $7 $1)       ; next pixel
        (jump-lt-int &draw-box-inner $7 $6))

      (add-int $4 $4 $2)         ; next row (+= 640)
      (sub-int $5 $5 $1)         ; decrement row count
      (jump-gt-int &draw-box-outer $5 0))
    (return)))
(data
	(label screen-namespace "/dev/screen/0")
  (label mouse-namespace "/dev/mouse/0")
	(label BLACK 0)
	(label WHITE 255)
	(label CHARCOAL 36)
	(label DARK-GRAY 73)
	(label GRAY 146)
	(label LIGHT-GRAY 182)
	(label DARK-RED 128)
	(label RED 224)
	(label DARK-YELLOW 144)
	(label YELLOW 252)
	(label DARK-TEAL 9)
	(label TEAL 18)
	(label DARK-GREEN 12)
	(label GREEN 16)
	(label LIME 28)
	(label LIGHT-CYAN 159)
	(label NAVY 2)
	(label BLUE 3)
	(label DEEP-SKY-BLUE 10)
	(label LIGHT-BLUE 19)
	(label PURPLE 131)
	(label LIGHT-PURPLE 147)
	(label DARK-MAGENTA 130)
	(label MAGENTA 227)
	(label PLUM 129)
	(label PINK 226)
	(label SADDLE-BROWN 72)
	(label PERU 141)
	(label SIENNA 136)
	(label ORANGE 241)
	(label DARK-ORANGE 208)
	(label GOLD 244)))