#include <obd2/obd2.h>
#include <arpa/inet.h>
#define MODE_RESPONSE_OFFSET 0x40
#define NEGATIVE_RESPONSE_MODE 0x7f
#define MAX_DIAGNOSTIC_PAYLOAD_SIZE 6
#define MODE_BYTE_INDEX 0
#define PID_BYTE_INDEX 1
#define NEGATIVE_RESPONSE_MODE_INDEX 1
#define NEGATIVE_RESPONSE_NRC_INDEX 2
DiagnosticShims diagnostic_init_shims(LogShim log,
SendCanMessageShim send_can_message,
SetTimerShim set_timer) {
DiagnosticShims shims = {
log: log,
send_can_message: send_can_message,
set_timer: set_timer
};
return shims;
}
DiagnosticRequestHandle diagnostic_request(DiagnosticShims* shims,
DiagnosticRequest* request, DiagnosticResponseReceived callback) {
DiagnosticRequestHandle handle = {
// TODO can we copy the request?
request: *request,
callback: callback,
success: false,
completed: false
};
uint8_t payload[MAX_DIAGNOSTIC_PAYLOAD_SIZE];
payload[MODE_BYTE_INDEX] = request->mode;
if(request->pid_length > 0) {
copy_bytes_right_aligned(&request->pid, sizeof(request->pid),
PID_BYTE_INDEX, request->pid_length, payload, sizeof(payload));
}
if(request->payload_length > 0) {
memcpy(&payload[PID_BYTE_INDEX + request->pid_length],
request->payload, request->payload_length);
}
handle.isotp_shims = isotp_init_shims(shims->log,
shims->send_can_message,
shims->set_timer);
handle.isotp_send_handle = isotp_send(&handle.isotp_shims,
request->arbitration_id, payload,
1 + request->payload_length + request->pid_length,
NULL);
handle.isotp_receive_handle = isotp_receive(&handle.isotp_shims,
// TODO need to either always add 0x8 or let the user specify
request->arbitration_id + 0x8,
NULL);
// when a can frame is received and passes to the diagnostic handle
// if we haven't successfuly sent the entire message yet, give it to the
// isottp send handle
// if we have sent it, give it to the isotp rx handle
// if we've received properly, mark this request as completed
// how do you get the result? we have it set up for callbacks but that's
// getting to be kind of awkward
//
// say it were to call a callback...what state would it need to pass?
//
// the iso-tp message received callback needs to pass the handle and the
// received message
//
// so in the obd2 library, we get a callback with an isotp message. how do
// we know what diag request i went with, and which diag callback to use? we
// could store context with the isotp handle. the problem is that context is
// self referential and on the stack, so we really can't get a pointer to
// it.
//
// the diagnostic response received callback needs to pass the diagnostic
// handle and the diag response
//
// let's say we simplify things and drop the callbacks.
//
// isotp_receive_can_frame returns an isotp handle with a complete message
// in it if one was received
//
// diagnostic_receive_can_frame returns a diaghandle if one was received
//
// so in the user code you would throw the can frame at each of your active
// diag handles and see if any return a completed message.
//
// is there any advantage to a callback approach? callbacks are useful when
// you have something that will block, bt we don't have anything that will
// block. it's async but we return immediately from each partial parsing
// attempt.
//
// argh, but will we need the callbacks when we add timers for isotp multi
// frame?
//
// what are the timers for exactly?
//
// when sending multi frame, send 1 frame, wait for a response
// if it says send all, send all right away
// if it says flow control, set the time for the next send
// instead of creating a timer with an async callback, add a process_handle
// function that's called repeatedly in the main loop - if it's time to
// send, we do it. so there's a process_handle_send and receive_can_frame
// that are just called continuously from the main loop. it's a waste of a
// few cpu cycles but it may be more natural than callbacks.
//
// what woudl a timer callback look like...it would need to pass the handle
// and that's all. seems like a context void* would be able to capture all
// of the information but arg, memory allocation. look at how it's done in
// the other library again
//
return handle;
}
DiagnosticRequestHandle diagnostic_request_pid(DiagnosticShims* shims,
DiagnosticPidRequestType pid_request_type, uint16_t arbitration_id,
uint16_t pid, DiagnosticResponseReceived callback) {
DiagnosticRequest request = {
arbitration_id: arbitration_id,
mode: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 0x1 : 0x22,
pid: pid,
pid_length: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 1 : 2
};
return diagnostic_request(shims, &request, callback);
}
DiagnosticResponse diagnostic_receive_can_frame(DiagnosticShims* shims,
DiagnosticRequestHandle* handle, const uint16_t arbitration_id,
const uint8_t data[], const uint8_t size) {
DiagnosticResponse response = {
arbitration_id: arbitration_id,
success: false,
completed: false
};
if(!handle->isotp_send_handle.completed) {
// TODO when completing a send, this returns...a Message? we have to
// check when the isotp_send_handle is completed, and if it is, start
isotp_continue_send(&handle->isotp_shims,
&handle->isotp_send_handle, arbitration_id, data, size);
} else if(!handle->isotp_receive_handle.completed) {
IsoTpMessage message = isotp_continue_receive(&handle->isotp_shims,
&handle->isotp_receive_handle, arbitration_id, data, size);
if(message.completed) {
if(message.size > 0) {
response.mode = message.payload[0];
if(response.mode == NEGATIVE_RESPONSE_MODE) {
if(message.size > NEGATIVE_RESPONSE_MODE_INDEX) {
// TODO we're setting the mode to the originating
// request for the error, so the user can confirm - i
// think this is OK since we're storing the failure
// status elsewhere, but think about it.
response.mode = message.payload[NEGATIVE_RESPONSE_MODE_INDEX];
}
if(message.size > NEGATIVE_RESPONSE_NRC_INDEX) {
response.negative_response_code = message.payload[NEGATIVE_RESPONSE_NRC_INDEX];
}
response.success = false;
} else {
if(response.mode == handle->request.mode + MODE_RESPONSE_OFFSET) {
// hide the "response" version of the mode from the user
// if it matched
response.mode = handle->request.mode;
if(handle->request.pid_length > 0 && message.size > 1) {
if(handle->request.pid_length == 2) {
response.pid = *(uint16_t*)&message.payload[PID_BYTE_INDEX];
response.pid = ntohs(response.pid);
} else {
response.pid = message.payload[PID_BYTE_INDEX];
}
}
uint8_t payload_index = 1 + handle->request.pid_length;
response.payload_length = message.size - payload_index;
if(response.payload_length > 0) {
memcpy(response.payload, &message.payload[payload_index],
response.payload_length);
}
response.success = true;
} else {
shims->log("Response was for a mode 0x%x request, not our mode 0x%x request",
response.mode - MODE_RESPONSE_OFFSET,
handle->request.mode);
}
}
}
response.completed = true;
// TODO what does it mean for the handle to be successful, vs. the
// request to be successful? if we get a NRC, is that a successful
// request?
handle->success = true;
handle->completed = true;
if(handle->callback != NULL) {
handle->callback(&response);
}
}
} else {
shims->log("Handle is already completed");
}
return response;
}
// TODO everything below here is for future work...not critical for now.
DiagnosticRequestHandle diagnostic_request_malfunction_indicator_status(
DiagnosticShims* shims,
DiagnosticMilStatusReceived callback) {
// TODO request malfunction indicator light (MIL) status - request mode 1
// pid 1, parse first bit
}
DiagnosticRequestHandle diagnostic_request_vin(DiagnosticShims* shims,
DiagnosticVinReceived callback) {
}
DiagnosticRequestHandle diagnostic_request_dtc(DiagnosticShims* shims,
DiagnosticTroubleCodeType dtc_type,
DiagnosticTroubleCodesReceived callback) {
}
bool diagnostic_clear_dtc(DiagnosticShims* shims) {
}
DiagnosticRequestHandle diagnostic_enumerate_pids(DiagnosticShims* shims,
DiagnosticRequest* request, DiagnosticPidEnumerationReceived callback) {
// before calling the callback, split up the received bytes into 1 or 2 byte
// chunks depending on the mode so the final pid list is actual 1 or 2 byte PIDs
// TODO request supported PIDs - request PID 0 and parse 4 bytes in response
}