X-Git-Url: http://git.osdn.net/view?a=blobdiff_plain;f=transform.c;h=8b525d177122f5efd7d92c73e735a8fbedda8176;hb=b24d6584ce3c44cdb5ba9ebe6aa525ff7ecd477c;hp=74582a79fac83bf5fa894b6f94481115a2bd0cee;hpb=966751be50b3ae8d7a8c6e2e61eef1aacd1c5fda;p=android-x86%2Fhardware-intel-libsensors.git

diff --git a/transform.c b/transform.c
index 74582a7..8b525d1 100644
--- a/transform.c
+++ b/transform.c
@@ -199,10 +199,10 @@ static void denoise (struct sensor_info_t* si, struct sensors_event_t* data,
 	 */
 
 	int i;
-	float total;
 	int f;
 	int sampling_rate = (int) si->sampling_rate;
 	int history_size;
+	int history_full = 0;
 
 	/* Don't denoise anything if we have less than two samples per second */
 	if (sampling_rate < 2)
@@ -221,32 +221,43 @@ static void denoise (struct sensor_info_t* si, struct sensors_event_t* data,
 		si->history_index = 0;
 		si->history = (float*) realloc(si->history,
 				si->history_size * num_fields * sizeof(float));
+		if (si->history) {
+			si->history_sum = (float*) realloc(si->history_sum,
+				num_fields * sizeof(float));
+			if (si->history_sum)
+				memset(si->history_sum, 0, num_fields * sizeof(float));
+		}
 	}
 
-	if (!si->history)
+	if (!si->history || !si->history_sum)
 		return;	/* Unlikely, but still... */
 
 	/* Update initialized samples count */
 	if (si->history_entries < si->history_size)
 		si->history_entries++;
+	else
+		history_full = 1;
 
-	/* Record new sample */
-	for (f=0; f < num_fields; f++)
-		si->history[si->history_index * num_fields + f] = data->data[f];
-
-	/* Update our rolling index (next evicted cell) */
-	si->history_index = (si->history_index + 1) % si->history_size;
-
-	/* For now simply compute a mobile mean for each field */
+	/* Record new sample and calculate the moving sum */
 	for (f=0; f < num_fields; f++) {
-		total = 0;
+		/**
+		 * A field is going to be overwritten if
+		 * history is full, so decrease the history sum
+		 */
+		if (history_full)
+			si->history_sum[f] -=
+				si->history[si->history_index * num_fields + f];
 
-		for (i=0; i < si->history_entries; i++)
-				total += si->history[i * num_fields + f];
+		si->history[si->history_index * num_fields + f] = data->data[f];
+		si->history_sum[f] += data->data[f];
 
-		/* Output filtered data */
-		data->data[f] = total / si->history_entries;
+		/* For now simply compute a mobile mean for each field */
+		/* and output filtered data */
+		data->data[f] = si->history_sum[f] / si->history_entries;
 	}
+
+	/* Update our rolling index (next evicted cell) */
+	si->history_index = (si->history_index + 1) % si->history_size;
 }