reinzor / libcan-encode-decode

C++ functions for encoding and decoding CAN frames ( uint8_t[8] )

libcan-encode-decode

C++ functions for encoding and decoding CAN frames ( uint8_t[8] )

Usage

Copy the include/can_encode_decode.inl into your c++ project and use the inline functions.

uint8_t src_array[8];

encode(src_array, 3.0, 56, 3, false, false, 1.000000, 0);
decode(src_array, 56, 3, false, false, 1.000000, 0); // 3.0

encode(src_array, 35, 2, 6, true, false, 1.0, 0);
decode(src_array, 2, 6, true, false, 1.000000, 0) // 35.000000

encode(src_array, 1.0, 0, 2, true, false, 1.0, 0);
decode(src_array, 0, 2, true, false, 1.000000, 0); // 1.000000

Run tests

./run_tests.sh

libcan-encode-decode's Issues

storeSignal does not clear out stale bits

Hello,

Thank you for this wonderful library! One thing I've noticed is that when you call storeSignal, it does not clear out the old bits that were in the CAN frame. Instead, it leaves them there so if the new value is smaller those bits get overwritten, but the remaining bits (left-over from the last value that was there) are not changed. Any suggestions on how to clear the entire range (i.e. from startbit 5 to a length of 16) out before storing a value? Thanks!

Start bit in motorola signals from Vector dbc files

Hi

I noted in Vector dbc files (opened as a txt file) the start bit field is the real start bit when signal is intel byte order, but is the 'end bit' when signal is motorola byte order. Have you seen this? How do you handle that (because storeSignal and extractSignal must receive both the real start bit position)?

Thanks

Laercio

encoding into more than 8 bits

I would like to encode a value into 11 bits in a CAN frame. It seems like there is an overflow condition or something similar that is happening and I am not able to stuff these into required bits. Is there a limitation of this repo that would prevent me from encoding to more than 8 bits?

Encode does not properly deal with sign extension

@ebroecker @laercio-barbosa

It appears that the sign extension is not properly handled yet. I added a test that currently fails. I would like to have some help with this :).

Thanks!

libwecan in C

Hi,

I did the same as you in C you might be interested.

https://github.com/nisennenmondai/libwecan

nisen,

datatype error

Hi.

I am trying to use your inline decode function from your repo and I am getting error message as below.

Foe the frame, I am sending data field from a struct called msg as below which is an uint8_t array of 8 members. The error is also attached below. Please let me know

Code

msg.data[0] = 0x53;
msg.data[1] = 0x40;
msg.data[2] = 0x40;
msg.data[3] = 0x0;
msg.data[4] = 0x0;
msg.data[5] = 0x0;
msg.data[6] = 0x10;
msg.data[7] = 0xBD;

msg.header.frame_id = ""; // "0" for no frame.
msg.header.stamp = ros::Time::now();

uint8_t msg.data[8];

//encode(src_array, 3.0, 56, 3, false, false, 1.000000, 0);
float PhysValue = decode(msg.data, 2,11, false, false, 1.000000, 0); // 3.0

Error

home/jpm/catkin_ws/src/ros_canopen/socketcan_bridge/src/steering_pub_socketcan.cpp: In function ‘int main(int, char**)’:
/home/jpm/catkin_ws/src/ros_canopen/socketcan_bridge/src/steering_pub_socketcan.cpp:118:12: error: expected initializer before ‘.’ token
uint8_t msg.data[8] = 0;
^
/home/jpm/catkin_ws/src/ros_canopen/socketcan_bridge/src/steering_pub_socketcan.cpp:121:67: error: cannot convert ‘can_msgs::Frame_<std::allocator >::_data_type {aka boost::array<unsigned char, 8ul>}’ to ‘const uint8_t* {aka const unsigned char*}’ for argument ‘1’ to ‘float decode(const uint8_t*, uint16_t, uint16_t, bool, bool, float, float)’
float PhysValue = decode(msg.data, 2,11, false, false, 1.000000, 0); // 3.0
^
ros_canopen/socketcan_bridge/CMakeFiles/talker.dir/build.make:62: recipe for target 'ros_canopen/socketcan_bridge/CMakeFiles/talker.dir/src/steering_pub_socketcan.cpp.o' failed
make[2]: *** [ros_canopen/socketcan_bridge/CMakeFiles/talker.dir/src/steering_pub_socketcan.cpp.o] Error 1
CMakeFiles/Makefile2:3705: recipe for target 'ros_canopen/socketcan_bridge/CMakeFiles/talker.dir/all' failed
make[1]: *** [ros_canopen/socketcan_bridge/CMakeFiles/talker.dir/all] Error 2
Makefile:138: recipe for target 'all' failed
make: *** [all] Error 2

Fix missing semicolon

The last chenge introduced a error. There is a missing semicolon in can_encode_decode_inl.h - line 38.

frame[start_byte] |= value << startbit_in_byte

Signal extension implementation

Hi,

Here is the implementation for signal extension in storeSignal as I promissed. Regarding issue ebroecker/canmatrix#35.

        if (is_signed)
        {
            uint64_t signal_value;
            // Save signal value
            // perform sign extension
            // update value
            signal_value = value & 0x8000000000000000;
            value |= signal_value >> (64 - length);
        }