Nicholas Outram
/
Task328
Lab version
main.cpp@1:ccec17874183, 2017-07-13 (annotated)
- Committer:
- noutram
- Date:
- Thu Jul 13 14:49:20 2017 +0000
- Revision:
- 1:ccec17874183
- Parent:
- 0:c6ec99d3da16
updated for mbed-os 5.5
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
noutram | 0:c6ec99d3da16 | 1 | #include "mbed.h" |
noutram | 0:c6ec99d3da16 | 2 | #define N 100000 |
noutram | 0:c6ec99d3da16 | 3 | #define RELEASED 1 |
noutram | 0:c6ec99d3da16 | 4 | #define PRESSED 0 |
noutram | 0:c6ec99d3da16 | 5 | DigitalOut red_led(D7); //CountUp is in its critical section |
noutram | 0:c6ec99d3da16 | 6 | DigitalOut yellow_led(D6); //CountDown is in its critical section |
noutram | 0:c6ec99d3da16 | 7 | DigitalOut green_led(D5); //counter != 0 |
noutram | 0:c6ec99d3da16 | 8 | DigitalIn button(USER_BUTTON); |
noutram | 0:c6ec99d3da16 | 9 | |
noutram | 0:c6ec99d3da16 | 10 | //Shared mutable state |
noutram | 0:c6ec99d3da16 | 11 | volatile long long counter = 0; //Volatile means it must be stored in memory |
noutram | 0:c6ec99d3da16 | 12 | |
noutram | 0:c6ec99d3da16 | 13 | //Increment the shared variable |
noutram | 0:c6ec99d3da16 | 14 | void countUp() |
noutram | 0:c6ec99d3da16 | 15 | { |
noutram | 0:c6ec99d3da16 | 16 | //RED MEANS THE COUNT UP FUNCTION IS IN ITS CRITICAL SECTION |
noutram | 0:c6ec99d3da16 | 17 | red_led = 1; |
noutram | 0:c6ec99d3da16 | 18 | for (int n=0; n<N; n++) { |
noutram | 0:c6ec99d3da16 | 19 | counter++; |
noutram | 0:c6ec99d3da16 | 20 | counter++; |
noutram | 0:c6ec99d3da16 | 21 | counter++; |
noutram | 0:c6ec99d3da16 | 22 | counter++; |
noutram | 0:c6ec99d3da16 | 23 | counter++; |
noutram | 0:c6ec99d3da16 | 24 | counter++; |
noutram | 0:c6ec99d3da16 | 25 | counter++; |
noutram | 0:c6ec99d3da16 | 26 | counter++; |
noutram | 0:c6ec99d3da16 | 27 | counter++; |
noutram | 0:c6ec99d3da16 | 28 | counter++; |
noutram | 0:c6ec99d3da16 | 29 | } |
noutram | 0:c6ec99d3da16 | 30 | red_led = 0; |
noutram | 0:c6ec99d3da16 | 31 | |
noutram | 0:c6ec99d3da16 | 32 | //Last to finish turnes out the green light |
noutram | 0:c6ec99d3da16 | 33 | if (counter == 0) { |
noutram | 0:c6ec99d3da16 | 34 | green_led = 0; |
noutram | 0:c6ec99d3da16 | 35 | } |
noutram | 0:c6ec99d3da16 | 36 | } |
noutram | 0:c6ec99d3da16 | 37 | |
noutram | 0:c6ec99d3da16 | 38 | //Decrement the shared variable |
noutram | 0:c6ec99d3da16 | 39 | void countDown() |
noutram | 0:c6ec99d3da16 | 40 | { |
noutram | 0:c6ec99d3da16 | 41 | //YELLOW MEANS THE COUNT DOWN FUNCTION IS IN ITS CRITICAL SECTION |
noutram | 0:c6ec99d3da16 | 42 | yellow_led = 1; |
noutram | 0:c6ec99d3da16 | 43 | for (int n=0; n<N; n++) { |
noutram | 0:c6ec99d3da16 | 44 | counter--; |
noutram | 0:c6ec99d3da16 | 45 | counter--; |
noutram | 0:c6ec99d3da16 | 46 | counter--; |
noutram | 0:c6ec99d3da16 | 47 | counter--; |
noutram | 0:c6ec99d3da16 | 48 | counter--; |
noutram | 0:c6ec99d3da16 | 49 | counter--; |
noutram | 0:c6ec99d3da16 | 50 | counter--; |
noutram | 0:c6ec99d3da16 | 51 | counter--; |
noutram | 0:c6ec99d3da16 | 52 | counter--; |
noutram | 0:c6ec99d3da16 | 53 | counter--; |
noutram | 0:c6ec99d3da16 | 54 | } |
noutram | 0:c6ec99d3da16 | 55 | yellow_led = 0; |
noutram | 0:c6ec99d3da16 | 56 | |
noutram | 0:c6ec99d3da16 | 57 | //Last to finish turns out the green light |
noutram | 0:c6ec99d3da16 | 58 | if (counter == 0) { |
noutram | 0:c6ec99d3da16 | 59 | green_led = 0; |
noutram | 0:c6ec99d3da16 | 60 | } |
noutram | 0:c6ec99d3da16 | 61 | } |
noutram | 0:c6ec99d3da16 | 62 | int main() { |
noutram | 0:c6ec99d3da16 | 63 | |
noutram | 0:c6ec99d3da16 | 64 | green_led = 1; |
noutram | 0:c6ec99d3da16 | 65 | Timeout t1; |
noutram | 0:c6ec99d3da16 | 66 | |
noutram | 0:c6ec99d3da16 | 67 | // TRY EACH OF THESE LINES IN TURN. |
noutram | 0:c6ec99d3da16 | 68 | // ALL IT DOES IS CHANGE THE TIMING OF THE ISR, NOT THE FUNCTION |
noutram | 0:c6ec99d3da16 | 69 | |
noutram | 0:c6ec99d3da16 | 70 | if (button == PRESSED) { |
noutram | 0:c6ec99d3da16 | 71 | //VERSION 2: short delay allowing main to be preempted - you might want to tweak this value |
noutram | 0:c6ec99d3da16 | 72 | t1.attach_us(&countDown, 15); |
noutram | 0:c6ec99d3da16 | 73 | } else { |
noutram | 0:c6ec99d3da16 | 74 | //VERSION 1: 2s - ENOUGH TIME FOR COUNTUP TO FINISH |
noutram | 0:c6ec99d3da16 | 75 | t1.attach(&countDown, 2); |
noutram | 0:c6ec99d3da16 | 76 | } |
noutram | 0:c6ec99d3da16 | 77 | |
noutram | 0:c6ec99d3da16 | 78 | //Run count up on the main thread |
noutram | 0:c6ec99d3da16 | 79 | countUp(); |
noutram | 0:c6ec99d3da16 | 80 | |
noutram | 0:c6ec99d3da16 | 81 | //Now spin-lock for ever |
noutram | 0:c6ec99d3da16 | 82 | while(1) { |
noutram | 0:c6ec99d3da16 | 83 | asm("nop"); |
noutram | 0:c6ec99d3da16 | 84 | }; |
noutram | 0:c6ec99d3da16 | 85 | } |
noutram | 0:c6ec99d3da16 | 86 |