PowerStatus: fix a possible division error.

* also fix some types misuses.

src/apps/powerstatus/ACPIDriverInterface.cpp

@@ -43,8 +43,8 @@ RateBuffer::AddRate(int32 rate)
 int32
 RateBuffer::GetMeanRate()
 {
-	int mean = 0;
-	for (int i = 0; i < fCurrentSize; i++) {
+	int32 mean = 0;
+	for (int8 i = 0; i < fCurrentSize; i++) {
 		mean += fRateBuffer[i];
 	}
 
@@ -98,7 +98,7 @@ Battery::GetBatteryInfoCached(battery_info* info)
 	info->capacity = fCachedAcpiInfo.capacity;
 	info->full_capacity = fExtendedBatteryInfo.last_full_charge;
 	fRateBuffer.AddRate(fCachedAcpiInfo.current_rate);
-	if (fCachedAcpiInfo.current_rate > 0)
+	if (fCachedAcpiInfo.current_rate > 0 && fRateBuffer.GetMeanRate() != 0)
 		info->time_left = 3600 * fCachedAcpiInfo.capacity
 			/ fRateBuffer.GetMeanRate();
 	else
@@ -254,5 +254,3 @@ ACPIDriverInterface::_FindDrivers(const char* dirpath)
 	}
 	return status;
 }
-
-

src/apps/powerstatus/PowerStatusView.cpp

@@ -336,7 +336,7 @@ void
 PowerStatusView::Update(bool force)
 {
 	int32 previousPercent = fPercent;
-	bool previousTimeLeft = fTimeLeft;
+	time_t previousTimeLeft = fTimeLeft;
 	bool wasOnline = fOnline;
 
 	_GetBatteryInfo(&fBatteryInfo, fBatteryID);
@@ -350,7 +350,7 @@ PowerStatusView::Update(bool force)
 	} else {
 		fPercent = 0;
 		fOnline = false;
-		fTimeLeft = false;
+		fTimeLeft = -1;
 	}
 
 
@@ -375,7 +375,7 @@ PowerStatusView::Update(bool force)
 			if (fHasBattery) {
 				size_t length = snprintf(text, sizeof(text), "%s%" B_PRId32
 					"%%%s", open, fPercent, close);
-				if (fTimeLeft) {
+				if (fTimeLeft >= 0) {
 					length += snprintf(text + length, sizeof(text) - length,
 						"\n%" B_PRId32 ":%02" B_PRId32, fTimeLeft / 3600,
 						(fTimeLeft / 60) % 60);
@@ -751,4 +751,3 @@ instantiate_deskbar_item(void)
 {
 	return new PowerStatusReplicant(BRect(0, 0, 15, 15), B_FOLLOW_NONE, true);
 }
-