refactoring: reducing code duplication

firmware/controllers/can/can_vss.cpp

@@ -31,21 +31,24 @@ static expected<uint16_t> look_up_can_id(can_vss_nbc_e type) {
 	}
 }
 
-/* Module specitifc processing functions */
+static int getTwoBytesLsb(const CANRxFrame& frame, int index) {
+	uint8_t low = frame.data8[index];
+	uint8_t high = frame.data8[index + 1] & 0x0F;
+	return low | (high << 8);
+}
+
+/* Module specific processing functions */
 /* source: http://z4evconversion.blogspot.com/2016/07/completely-forgot-but-it-does-live-on.html */
 float processBMW_e46(const CANRxFrame& frame) {
 	// average the rear wheels since those are the driven ones (more accurate gear detection!)
-	uint16_t left =  (((frame.data8[5] & 0x0f) << 8) | frame.data8[4]);
-	uint16_t right = (((frame.data8[7] & 0x0f) << 8) | frame.data8[6]);
+	uint16_t left =  getTwoBytesLsb(frame, 4);
+	uint16_t right = getTwoBytesLsb(frame, 6);
 
 	return (left + right) / (16 * 2);
 }
 
 float processBMW_e90(const CANRxFrame& frame) {
-	uint8_t low = frame.data8[0];
-	uint8_t high = frame.data8[1] & 0x0F;
-
-	return 0.1f * (low | (high << 8));
+	return 0.1f * getTwoBytesLsb(frame, 0);
 }
 
 float processW202(const CANRxFrame& frame) {