Question

I have three operations. Each operation is in a loop and has a flag value that decreases when the operation is running. While the operation is running, any other operation with the flag value reaching the maximum threshold should interrupt it and run instead (has the highest priority). The flag value changes according to a differential equation against time.

• I want each operation’s flag value to increase when another operation is running, and signal the system to switch to it when the flag value reaches the maximum threshold.
• The flag value of each operation increases and decreases according to a specific differential equation that changes with time when the operation is running.

All operations are currently in one file, looped in a Switch case statement. The current code is :

while 1
  [value, index]=max(flag);
  switch index
      case 1
          operation1
          ...
          ...
          flag = [x y z]
      case 2
          operation2
          ...
          ...
          flag = [x y z]
      case 3
          operation3
          ...
          ...
          flag = [x y z]
    end
end

Any ideas ? If you need me to explain a bit better then please do tell me.

Answer 1

There are several approaches here

1. Each time an operation is run, the others should gain some weight, the next time an operation is selected the one with the highest weight is chosen.
2. Each millisecond an operation is run, the others should gain some weight, the next time an operation is selected the one with the highest weight is chosen.
3. Each millisecond an operation is run, the others should gain some weight. As soon as an operation loses its highest flag status it should be interrupted.

Each requires a different solution

---

Here are some suggested solutions, for the corresponding problems:

1. Fairly trivial, just increase the flag of all operations by 1 everytime you run an operation, or alternately reduce the flag of this operation by 1.
2. Measure the time that it took to complete the operation (perhaps with tic and toc), increase the flag of all other operations with this value.
3. Give the flag as input to the operation, and inside the operation stop when the elapsed time lets this operation exceed one other flag. Note that without adjustment this means that you basically try to alternate operations by the millisecond.