Efficient way to wait for an interrupt in C

Question

I use WiringPi on a raspberry pi. With it, I assign an interrupt function that is called later. I'm not sure what to do while waiting for an interupt call.

The examples use (spinlock?) for (;;)For example.

int main()
{
    // register interrupt
    wiringPiISR( 18, INT_EDGE_BOTH, &myInterrupt );

    for (;;) {
        // really?
    }
    return 0;
}

And I noticed that it sleepworks too. Interruption is called independent of sleep

int main() 
{
    // register interrupt
    wiringPiISR( 18, INT_EDGE_BOTH, &myInterrupt );

    for (;;) {
        sleep(1000000);
    }
    return 0;
}

What is the best practice for keeping the program running with minimal resources (say, if it was for a background daemon)?

Coming from other languages, I would think that it for(;;)will consume resources. I would like to know what to do or pointers to what to do (threads, etc.).

Answer 1

. KISS. sleep - , .

, Pi B:

int main() 
{
    // register interrupt
    wiringPiISR( 18, INT_EDGE_BOTH, &myInterrupt );

    for (;;) {
        sleep(UINT_MAX);
    }
    return 0;
}

UINT_MAX - 32- , WiringPi.

Answer 2

WiringPi isr .

pthread, , main() , isr .

#include <pthread.h>

pthread_cond_t isr_cond = PTHREAD_COND_INITIALIZER;
pthread_mutex_t isr_mtx = PTHREAD_MUTEX_INITIALIZER;
unsigned int isr_count = 0;

void myInterrupt(void)
{
    pthread_mutex_lock(&isr_mtx);
    isr_count++;
    pthread_cond_signal(&isr_cond);    
    pthread_mutex_unlock(&isr_mtx);

}

int main() 
{
    // register interrupt
    wiringPiISR( 18, INT_EDGE_BOTH, &myInterrupt );

    for (;;) {
       pthread_mutex_lock(&isr_mtx);
       while (isr_count == 0) {
          pthread_cond_wait(&isr_cond, &isr_mtx);
       }
       //add logic here to handle the ISR, isr_count
       //tells you how many ISRs occured.
       //heavy work should be moved outside the mutex.

      isr_count = 0;
      pthread_mutex_unlock(&isr_mtx);
    }

    return 0;
}

-pthread.

Answer 3

, . :

1) " , ". , main(), Sleep(), Sleep (INFINITE), , - , , - "set low power state" "HALT". neeed .

2) " , ". , int boolean () , . , , :)

3) " , ". "" , "" , , . /. , . /condvars, , .

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Answer 4

semaphore. sem_post() :

#include <semaphore.h>

static sem_t staticSem;

void myInterupt( void )
{
    sem_post( &staticSem );
}

int main() 
{
    sem_init( &staticSem, 0, 0 );

    // register interrupt
    wiringPiISR( 18, INT_EDGE_BOTH, &myInterrupt );

    for (;;) {
        sem_wait( &staticSem );
        ...
    }
    return 0;
}

sem_wait() .

Answer 5

( do, ) - while(1) ;. - .

, , . , .

sleep(0xFFFFFFFF); Intel Core i3-4330TE:

        .file   "test.c"
        .text
        .globl  main
        .type   main, @function
main:
.LFB0:
        .cfi_startproc
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
        movl    $-1, %edi
        movl    $0, %eax
        call    sleep
        movl    $0, %eax
        popq    %rbp
        .cfi_def_cfa 7, 8
        ret
        .cfi_endproc
.LFE0:
        .size   main, .-main
        .ident  "GCC: (Debian 4.9.2-10) 4.9.2"
        .section        .note.GNU-stack,"",@progbits

a while(1);:

        .file   "test.c"
        .text
        .globl  main
        .type   main, @function
main:
.LFB0:
        .cfi_startproc
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
.L2:
        jmp     .L2
        .cfi_endproc
.LFE0:
        .size   main, .-main
        .ident  "GCC: (Debian 4.9.2-10) 4.9.2"
        .section        .note.GNU-stack,"",@progbits

, , . , linux , ISR.

---

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Answer 6

WiringPi , pthread_cond_t, signal , ?

.