sign: handle decode methods sign from can value

[apps/agl-service-can-low-level.git] / low-can-binding / can / can-decoder.cpp

diff --git a/low-can-binding/can/can-decoder.cpp b/low-can-binding/can/can-decoder.cpp
index a6b6c14..f64a843 100644 (file)
--- a/low-can-binding/can/can-decoder.cpp
+++ b/low-can-binding/can/can-decoder.cpp
@@ -23,6 +23,66 @@
 #include "../binding/low-can-hat.hpp"
 #include "../utils/converter.hpp"
 
+/// @brief Handle sign of the signal according to several decoding methods
+///
+/// @param[in] signal - The signal
+/// @param[in] data_signal - The data of the signal
+/// @param[in] new_end_bit - The last bit of in the last byte of the data (data_signal[0])
+/// @param[in] can_data - The whole can data (needed for SIGN BIT EXTERN)
+///
+/// @return Returns the sign of the data
+///
+int decoder_t::handle_sign(const signal_t& signal, std::vector<uint8_t>& data_signal, uint8_t new_end_bit, const std::vector<uint8_t>& can_data)
+{
+       uint8_t data_byte = 0;
+       uint8_t mask = 0;
+       int end_bit = 0;
+
+       if(signal.get_sign() == sign_t::UNSIGNED)
+               return 1;
+       else if(signal.get_sign() == sign_t::SIGN_BIT_EXTERN) {
+               end_bit = signal.get_bit_sign_position()%8;
+               mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
+               data_byte = can_data[signal.get_bit_sign_position()/8] & mask;
+       }
+       else {
+               end_bit = new_end_bit;
+               mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
+               data_byte = data_signal[0] & mask;
+       }
+
+       //if negative: decode with right method
+       if(data_byte  >> end_bit) {
+               switch(signal.get_sign())
+               {
+                       //remove the sign bit to get the absolute value
+                       case sign_t::SIGN_BIT:
+                               data_signal[0] = static_cast<uint8_t>(data_signal[0] & (mask >> 1));
+                               break;
+                       //same method twos complement = ones complement + 1
+                       case sign_t::ONES_COMPLEMENT:
+                       case sign_t::TWOS_COMPLEMENT:
+                               //complement only until end_bit
+                               data_signal[0] = ((data_signal[0] ^ mask) & mask);
+                               if(data_signal.size() > 1) {
+                                       for(int i=1; i < data_signal.size(); i++) {
+                                               data_signal[i] = data_signal[i] ^ 0xFF;
+                                       }
+                               }
+                               if(signal.get_sign() == sign_t::TWOS_COMPLEMENT)
+                                       data_signal[data_signal.size() - 1] = static_cast<uint8_t>(data_signal[data_signal.size() - 1] + 1);
+                               break;
+                       case sign_t::SIGN_BIT_EXTERN:
+                               break;
+                       default:
+                               AFB_ERROR("Not a valid sign entry %d, considering the value as unsigned", signal.get_sign());
+                               break;
+               }
+               return -1;
+       }
+       return 1;
+}
+
 /// @brief Parses the signal's bitfield from the given data and returns the raw
 /// value.
 ///
@@ -48,6 +108,9 @@ float decoder_t::parse_signal_bitfield(signal_t& signal, std::shared_ptr<message
 
        for(int i=new_start_byte;i<=new_end_byte;i++)
                data_signal.push_back(data[i]);
+       }
+
+       int sign = handle_sign(signal, data_signal, new_end_bit, data);
 
 //     if(bit_size > 255)
 //             AFB_ERROR("Error signal %s to long bit size", signal.get_name().c_str());
@@ -58,7 +121,7 @@ float decoder_t::parse_signal_bitfield(signal_t& signal, std::shared_ptr<message
        if(data_signal.size() > 65535)
                AFB_ERROR("Too long data signal %s", signal.get_name().c_str());
 
-       return bitfield_parse_float(data_signal.data(), (uint16_t) data_signal.size(),
+       return static_cast<float>(sign) * bitfield_parse_float(data_signal.data(), (uint16_t) data_signal.size(),
                        new_start_bit, bit_size, signal.get_factor(),
                        signal.get_offset());
 }
@@ -297,7 +360,7 @@ openxc_DynamicField decoder_t::translate_signal(signal_t& signal, std::shared_pt
        if(!signal.get_message()->frame_layout_is_little())
        {
                signal.set_bit_position(converter_t::bit_position_swap(signal.get_bit_position(),signal.get_bit_size()));
-       }       
+       }
        // 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,