Please read the question and its hints very well. Use the skeleton program as instructed and modify the lines in red color. Any submitted program that is not based on the provided skeleton will not be accepted.

The following program is the simple I$/$O sample program we discussed in class. The code is posted under Modules. Basically when the switch is open, LED$1$ toggles, and when switch is closed, LED$2$ toggles.

Modify the program, so that at the push of the button, the micro cycles through $4$ different modes of operation. The areas to be modified are marked below in red.

Hint: use a counting semaphore $(1-3),$ which is incremented whenever the switch is closed, and it resets to $1$ when it reaches value $>=4.$ When the switch is open, the software uses a case statement to execute the $4$ different modes of operations based on the semaphore value as follows:

value $1$; LED$1$ flashes while LED$2$ off

value $2$; LED$2$ flashes while LED$1$ off

value $3$; LED$1$ and LED$2$ flash simultaneously

value $4$: LED$1$ and LED alternate