Factor global variables into struct

1 files changed, 55 insertions, 55 deletions

diff --git a/motionMonitor/motionMonitor.c b/motionMonitor/motionMonitor.c
index 2622ea6..8f72c47 100644
--- a/motionMonitor/motionMonitor.c
+++ b/motionMonitor/motionMonitor.c
@@ -5,20 +5,10 @@
 
 #define N_CHANGE_BLOCKS 200
 #define SAMPLE_PERIOD_MS 100
+#define DEFAULT_THRESHOLD_MS2 10
 
 void* impactMonitor(void*);
 
-typedef struct {
-  double x;
-  double y;
-  double z;
-} Acceleration;
-
-double xAccImpact[N_CHANGE_BLOCKS];
-double yAccImpact[N_CHANGE_BLOCKS];
-double zAccImpact[N_CHANGE_BLOCKS];
-uint64_t timestamps[N_CHANGE_BLOCKS];
-
 static const char FormatStr[] = "/sys/bus/iio/devices/iio:device0/in_%s_%s";
 static const char AccType[] = "accel";
 static const char GyroType[] = "anglvel";
@@ -26,18 +16,20 @@ static const char CompX[] = "x_raw";
 static const char CompY[] = "y_raw";
 static const char CompZ[] = "z_raw";
 static const char CompScale[] = "scale";
-int totalImpacts = 0;
-static const double impactThreshold = 20.0;
 
-Acceleration suddenImpact = {0, 0, 0};
-
-pthread_t impactThread;
-pthread_mutex_t impactMutex;
+struct suddenImpacts_t {
+  int nValues;
+  double threshold;
+  double x[N_CHANGE_BLOCKS];
+  double y[N_CHANGE_BLOCKS];
+  double z[N_CHANGE_BLOCKS];
+  uint64_t timestamps[N_CHANGE_BLOCKS];
+  pthread_mutex_t lock;
+} impacts = {0, DEFAULT_THRESHOLD_MS2};
 
 /*
  * Reports the x, y and z accelerometer readings in meters per second squared.
-*/
-
+ */
 le_result_t brnkl_motion_getCurrentAcceleration(double* xAcc,
                                                 double* yAcc,
                                                 double* zAcc) {
@@ -73,17 +65,19 @@ done:
   return r;
 }
 
-le_result_t recordImpact(double* xAcc, double* yAcc, double* zAcc) {
-  if (totalImpacts > N_CHANGE_BLOCKS || totalImpacts > N_CHANGE_BLOCKS ||
-      totalImpacts > N_CHANGE_BLOCKS)
+le_result_t recordImpact(struct suddenImpacts_t* it,
+                         double xAcc,
+                         double yAcc,
+                         double zAcc) {
+  if (it->nValues > N_CHANGE_BLOCKS || it->nValues > N_CHANGE_BLOCKS ||
+      it->nValues > N_CHANGE_BLOCKS)
     return LE_OUT_OF_RANGE;
 
-  timestamps[totalImpacts] = GetCurrentTimestamp();
-  xAccImpact[totalImpacts] = *xAcc;
-  yAccImpact[totalImpacts] = *yAcc;
-  zAccImpact[totalImpacts] = *zAcc;
-  totalImpacts++;
-  LE_INFO("New Impact, totalImpacts: %d", totalImpacts);
+  it->timestamps[it->nValues] = GetCurrentTimestamp();
+  it->x[it->nValues] = xAcc;
+  it->y[it->nValues] = yAcc;
+  it->z[it->nValues] = zAcc;
+  it->nValues++;
 
   return LE_OK;
 }
@@ -96,67 +90,73 @@ le_result_t brnkl_motion_getSuddenImpact(double* xAcc,
                                          size_t* zSize,
                                          uint64_t* timestampssOut,
                                          size_t* timeSize) {
-  if (!totalImpacts)
+  if (!impacts.nValues)
     LE_INFO("No Sudden Impacts to Report");
   else {
-    pthread_mutex_lock(&impactMutex);
-    // check
+    pthread_mutex_lock(&impacts.lock);
 
-    if (totalImpacts > *xSize || totalImpacts > *ySize || totalImpacts > *zSize)
+    if (impacts.nValues > *xSize || impacts.nValues > *ySize ||
+        impacts.nValues > *zSize)
       return LE_OUT_OF_RANGE;
 
-    for (int i = 0; i < totalImpacts; i++) {
-      xAcc[i] = xAccImpact[i];
-      yAcc[i] = yAccImpact[i];
-      zAcc[i] = zAccImpact[i];
-      timestampssOut[i] = timestamps[i];
+    for (int i = 0; i < impacts.nValues; i++) {
+      xAcc[i] = impacts.x[i];
+      yAcc[i] = impacts.y[i];
+      zAcc[i] = impacts.y[i];
+      timestampssOut[i] = impacts.timestamps[i];
     }
 
-    *xSize = *ySize = *zSize = totalImpacts;
+    *xSize = *ySize = *zSize = impacts.nValues;
 
-    totalImpacts = 0;
+    impacts.nValues = 0;
 
-    pthread_mutex_unlock(&impactMutex);
+    pthread_mutex_unlock(&impacts.lock);
   }
 
   return LE_OK;
 }
 
 /*
-*Monitors accelerometer from iio on 100ms intervals
-*Sets hasSuddenImpact flag when accelerometer surpasses threshold
-*/
-void* impactMonitor(void* ptr) {
+ * Monitors accelerometer from iio on 100ms intervals
+ *
+ * We use a context pointer here such that this routine
+ * is not coupled to the global scope. This allows us to pass in
+ * a pointer to a struct that contains the data we care about
+ * instead of storing it globally. Ultimately, the struct we point to
+ * will likely be in the global scope, but this is still a good practice.
+ */
+void* impactMonitor(void* ctx) {
   double x, y, z;
   le_result_t r = LE_OK;
+  struct suddenImpacts_t* it = ctx;
   for (;;) {
     brnkl_motion_getCurrentAcceleration(&x, &y, &z);
 
     double impactMagnitude = sqrt(x * x + y * y + z * z);
 
-    if (impactMagnitude > impactThreshold) {
+    if (impactMagnitude > it->threshold) {
       // 3. add x, y, z to impact array
-      pthread_mutex_lock(&impactMutex);
-      r = recordImpact(&x, &y, &z);
-      pthread_mutex_unlock(&impactMutex);
+      pthread_mutex_lock(&it->lock);
+      r = recordImpact(it, x, y, z);
+      pthread_mutex_unlock(&it->lock);
     }
     if (r != LE_OK)
       LE_ERROR("Impact Not Recorded");
 
     usleep(SAMPLE_PERIOD_MS * 1000);
   }
-  return ptr;
+  // should never get here
+  return NULL;
 }
 
 /*
-*Create thread to monitor accelerometer iio
-*/
+ *Create thread to monitor accelerometer iio
+ */
 void initThread() {
+  pthread_t impactThread;
   int thread, mutx;
-  LE_INFO("initThread called");
-  mutx = pthread_mutex_init(&impactMutex, NULL);
-  thread = pthread_create(&impactThread, NULL, impactMonitor, NULL);
-  LE_INFO("mutexResult: %d", mutx);
+  mutx = pthread_mutex_init(&impacts.lock, NULL);
+  thread = pthread_create(&impactThread, NULL, impactMonitor, &impacts);
   if (thread || mutx) {
     LE_ERROR("Reader Thread or Mutex Creation Failed");
   } else {