Returning array values in a Struct in C for stepper motor

Question

I am attempting to spin a Stepper motor with a rabbit 4000 processor. I have a queue that will hold structs, and have created a function to create the sequence of binary bits need to run the 4 winding stepper motor. I am trying to pass the sequence from the function in side a struct to a producer that will fill the queue with it. The issue is I'm not getting the expected value put in the queue. Am i misunderstanding how to return a struct from a function, or do i need to assign the array values individually? The relevant chunks of code are:

typedef struct {
    char d[4];
    int  delayUs;
} mQueueEntry_t;


mQueueEntry_t setDirStep(int count0, int count1, int count2, int count3){

 mQueueEntry_t entry;

        entry.d[0] = (!((count0+1)%4));                 //1a
        entry.d[1] = (!((count1+1)%4));                 //1b
        entry.d[2] = (!((count2+1)%4));                 //2a
        entry.d[3] = (!((count3+1)%4));                 //2b

        entry.delayUs =10;
        printf("Breaking Funct with: %d,%d,%d,%d\n",entry.d[0], entry.d[1], entry.d[2], entry.d[3]);
}

// continually stuff a queue with a dedicated structure
void Producer(void* pdata){
    mQueueEntry_t entry;

    int count0 = 3;
    int count1=1;
    int count2=2;
    int count3=0;

    labQueue_t * q = (labQueue_t *) pdata;  // Note use of task data..
    printf("Hola Producer\n");
    while (1)
    {
        entry = setDirStep(count0, count1, count2, count3);
        printf("Values after funct call: %d,%d,%d,%d\n",entry.d[0], entry.d[1], entry.d[2], entry.d[3]);

        count0++;
        count1++;
        count2++;
        count3++;

        // send a copy of the element and
        switch ( labQueuePut( q, &entry) ){
        case LABQ_OK:
            printf("put %d,%d,%d,%d\n",entry.d[0], entry.d[1], entry.d[2], entry.d[3]);
            break;
        case LABQ_TIMEOUT:
            OSTimeDly(OS_TICKS_PER_SEC/10);
            break;
        case LABQ_FULL:
            OSTimeDly(OS_TICKS_PER_SEC/10);
            break;
        default:
            assert(0);
            break;
        }
        OSTimeDly(1);
      }

}

Screen output for program:

Hola Consumer
Hola Producer
Breaking Funct with: 1,0,0,0
Values after funct call: 235,0,24,23
received (1a= 0: 1b= 1: 2a= 0:2b= 0) 0
put 235,0,24,23
Breaking Funct with: 0,0,1,0
Values after funct call: 236,41,237,0
received (1a= 0: 1b= 0: 2a= 0:2b= 1) 1
put 236,41,237,0

My issue is with the values from breaking function to Values after funct call are expected to be the same.

Answer 1

Your setDirStep() is not returning a value, yet, you declared it as returning mQueueEntry_t. The values you read on this assignment will be invalid:

entry = setDirStep(count0, count1, count2, count3);

This should show a compiler warning, I'm surprised it doesn't.

To fix the error, add the necessary return statement in setDirStep():

return entry;

In the future, always make sure to compile with warnings turned on. If you're using gcc, all you need is -Wall.

The rest of the code looks ok