decoder: rework how to swap frame layout.

This also change the bit_position to retrieve the bit word starting from the left
or the right of the frame depending on the endianness of the frame layout.

Change-Id: I28658e9d46bd35d8ecabeece317331832229384a
Signed-off-by: Romain Forlot <romain.forlot@iot.bzh>

5 files changed, 21 insertions, 22 deletions

diff --git a/low-can-binding/can/can-decoder.cpp b/low-can-binding/can/can-decoder.cpp
index cf4306a5..0e64cccd 100644
--- a/low-can-binding/can/can-decoder.cpp
+++ b/low-can-binding/can/can-decoder.cpp
@@ -99,6 +99,14 @@ float decoder_t::parse_signal_bitfield(signal_t& signal, std::shared_ptr<message
 	uint8_t bit_size = (uint8_t) signal.get_bit_size();
 	uint32_t bit_position = signal.get_bit_position();
 
+	if(!signal.get_message()->frame_layout_is_little())
+	{
+		bit_position = converter_t::bit_position_swap(message->get_length(),
+							      signal.get_bit_position(),
+							      signal.get_bit_size());
+		message->frame_swap();
+	}
+
 	int new_start_byte = 0;
 	int new_end_byte = 0;
 	uint8_t new_start_bit = 0;
@@ -320,11 +328,6 @@ openxc_DynamicField decoder_t::decode_state(signal_t& signal, std::shared_ptr<me
 ///
 openxc_DynamicField decoder_t::translate_signal(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
 {
-	if(!signal.get_message()->frame_layout_is_little() && !signal.bit_position_is_swapped())
-	{
-		signal.set_bit_position(converter_t::bit_position_swap(signal.get_bit_position(),signal.get_bit_size()));
-		signal.bit_position_is_swapped_reverse();
-	}
 	// Must call the decoders every time, regardless of if we are going to
 	// decide to send the signal or not.
 	openxc_DynamicField decoded_value = decoder_t::decode_signal(signal,
diff --git a/low-can-binding/can/message/message.cpp b/low-can-binding/can/message/message.cpp
index 22887c9a..56e9379f 100644
--- a/low-can-binding/can/message/message.cpp
+++ b/low-can-binding/can/message/message.cpp
@@ -177,3 +177,14 @@ void message_t::set_length(uint32_t length)
 {
 	length_ = length;
 }
+
+void message_t::frame_swap()
+{
+	int i;
+	uint8_t *temp = (uint8_t*)alloca(length_);
+
+	for(i = 0; i < length_; i++)
+		temp[i] = data_[length_ - i - 1];
+
+	memcpy(data_.data(), temp, length_);
+}
diff --git a/low-can-binding/can/message/message.hpp b/low-can-binding/can/message/message.hpp
index 9a074e31..e5e6769b 100644
--- a/low-can-binding/can/message/message.hpp
+++ b/low-can-binding/can/message/message.hpp
@@ -44,7 +44,7 @@
 #define ISOTP_SEND 0x0020
 #define ISOTP_RECEIVE 0x0040
 #define CAN_PROTOCOL_WITH_FD_FRAME 0x0080
-#define FRAME_LAYOUT_IS_LE 0x0100
+#define FRAME_LAYOUT_IS_LE 0x0100 // LE stand for Little Endian
 
 /// @class message_t
 ///
@@ -84,4 +84,5 @@ public:
 	uint32_t get_maxdlen();
 	void set_maxdlen(uint32_t maxdlen);
 	void set_length(uint32_t length);
+	void frame_swap();
 };
diff --git a/low-can-binding/can/signals.cpp b/low-can-binding/can/signals.cpp
index 28246a05..da8df988 100755
--- a/low-can-binding/can/signals.cpp
+++ b/low-can-binding/can/signals.cpp
@@ -71,7 +71,6 @@ signal_t::signal_t(
 	, sign_{sign}
 	, bit_sign_position_{bit_sign_position}
 	, unit_{unit}
-	,bit_position_is_swapped_{false}
 {}
 
 signal_t::signal_t(
@@ -105,7 +104,6 @@ signal_t::signal_t(
 	, decoder_{decoder}
 	, encoder_{encoder}
 	, received_{received}
-	, bit_position_is_swapped_{false}
 {}
 
 std::shared_ptr<message_definition_t> signal_t::get_message() const
@@ -253,13 +251,3 @@ const std::string signal_t::get_unit() const
 {
 	return unit_;
 }
-
-bool signal_t::bit_position_is_swapped() const
-{
-	return bit_position_is_swapped_;
-}
-
-void signal_t::bit_position_is_swapped_reverse()
-{
-	bit_position_is_swapped_ = !bit_position_is_swapped_;
-}
diff --git a/low-can-binding/can/signals.hpp b/low-can-binding/can/signals.hpp
index 5f143753..bf779981 100755
--- a/low-can-binding/can/signals.hpp
+++ b/low-can-binding/can/signals.hpp
@@ -111,8 +111,6 @@ private:
 	sign_t sign_; /* !< sign_ - if the data is signed it indicates the encode */
 	int32_t bit_sign_position_; /*!< bit_sign_position_ - The bit that indicates the sign of the signal in its CAN message*/
 	std::string unit_; /* !< unit_ - The unit of the data */
-	bool bit_position_is_swapped_; /* !<bit_position_is_swapped_- True if the signal's bit position has been
-										swapped (refer to converter_t::bit_position_swap()). Default is false.*/
 
 public:
 
@@ -179,12 +177,10 @@ public:
 	sign_t get_sign() const;
 	int32_t get_bit_sign_position() const;
 	const std::string get_unit() const;
-	bool bit_position_is_swapped() const;
 
 	void set_parent(std::shared_ptr<message_definition_t> parent);
 	void set_received(bool r);
 	void set_last_value(float val);
 	void set_timestamp(uint64_t timestamp);
 	void set_bit_position(uint32_t bit_position);
-	void bit_position_is_swapped_reverse();
 };