assign3

@ Function Declaration : int mg_game_demo(int count, int delay)
@
@ Input: r0, r1, r2 (i.e. r0 holds delay, r1 holds pattern, r2 holds target)
@ Returns: 0
@

@ Here is the actual function
mg_game_demo:

    push {r4-r9, lr}                 @ Put aside registers we want to restore later
    mov r4, r0                       @ Stores the value of delay into r4
    mov r5, r1                       @ Stores the value of pattern into r5
    mov r6, r2                       @ Stores the value of target into r6

    reset_pattern:                   @ Resets the LED counter so you can do led_toggle_loop from scratch
    mov r7, r5                       @ r7 now holds the address of the value of the 1st LED to be toggled
    mov r9, #7                       @ r9 acts like a down counter of times left to loop


    led_toggle_loop:                 @ Toggle each LED once

        ldrb r8, [r7], #1            @ Load LED number(as an 8bit value, so only one char) into r8 add skip to next LED number
        sub r8, #48                  @ Convert ASCII value to decimal number

        mov r0, r8                   @ r0 now holds the number of LED to be toggled. Will be passed as a parameter
        bl BSP_LED_Toggle            @ call BSP C function using Branch with Link (bl)

        mov r0, r4                   @ r0 now holds the delay time, to be used in check_button_delay
        mov r1, r6                   @ r1 now holds the target LED value, to be used in check_button_delay
        mov r2, r8                   @ r2 now holds the ON LED value, to be used in check_button_delay
        bl check_button_delay        @ Calls busy_delay with r0,r1 and r2 as its arguments
        beq win                      @ If function returns 0, user pressed the button at the RIGHT time
        bmi lose                     @ If function returns -1, user pressed the button at the WRONG time

        mov r0,r8                    @ r0 now holds the number of LED to be toggled. Will be passed as a parameter
        bl   BSP_LED_Toggle          @ call BSP C function using Branch with Link (bl)

        subs r9, #1                  @ Count down until all the LEDs have been toggled
        bpl led_toggle_loop          @ Loop until all LEDs are toggled

    b reset_pattern                  @ Loop until we user presses the button


    win:                             @ Toggle all LED at the same time twice

        mov r0, r8                   @ r0 grabs the value of the LED currently ON...
        bl BSP_LED_Toggle            @ and here we turn it OFF

        mov r5, #3                   @ Store in r5 the number of times to toggle all LEDs

    reset_leds:

        mov r6, #7                   @ Store in r6 the total number of LEDs to be toggled

        toggle_all_leds_loop:

            mov r0,r6                @ r0 holds the value of the LED to be toggled
            bl BSP_LED_Toggle        @ Toggle LED

            subs r6, #1              @ Move to next LED
            bpl toggle_all_leds_loop


            mov r0, r4               @ r0 now holds the delay time, to be used in busy_delay
            bl busy_delay

            subs r5, #1              @ Subtract one from the number of times all LEDs need to be toggled
            bpl reset_leds

            b end

    lose:

        mov r0, r8                     @ r0 grabs the value of the LED currently ON...
        bl BSP_LED_Toggle              @ and here we turn it OFF

        mov r8, #5                     @ Store in r8 number of times the LED will be toggled

        toggle_one_led_loop:

            mov r0,r6                  @ r0 holds the value of target LED
            bl BSP_LED_Toggle

            mov r0, r4                 @ r0 now holds the delay time, to be used in busy_delay
            bl busy_delay

            subs r8, #1                @ Subtract one from the number of times this one LED needs to be toggled
            bpl toggle_one_led_loop


    end:
        mov r0, #0                     @ Return zero (always sucessful)
        pop {r4-r9,lr}                 @ Restore the orginal values of the registers
        bx lr                          @ Return (Branch eXchange) to the address in the link register (lr)

    .size   mg_game_demo, .-mg_game_demo    @@ - symbol size (not req)