src/obd2/obd2.c

   1 #include <obd2/obd2.h>
   2 #include <bitfield/bitfield.h>
   3 #include <string.h>
   4 #include <limits.h>
   5 #include <stddef.h>
   6 #include <sys/param.h>
   7
   8 #define ARBITRATION_ID_OFFSET 0x8
   9 #define MODE_RESPONSE_OFFSET 0x40
  10 #define NEGATIVE_RESPONSE_MODE 0x7f
  11 #define MAX_DIAGNOSTIC_PAYLOAD_SIZE 6
  12 #define MODE_BYTE_INDEX 0
  13 #define PID_BYTE_INDEX 1
  14 #define NEGATIVE_RESPONSE_MODE_INDEX 1
  15 #define NEGATIVE_RESPONSE_NRC_INDEX 2
  16
  17 DiagnosticShims diagnostic_init_shims(LogShim log,
  18         SendCanMessageShim send_can_message,
  19         SetTimerShim set_timer) {
  20     DiagnosticShims shims = {
  21         log: log,
  22         send_can_message: send_can_message,
  23         set_timer: set_timer
  24     };
  25     return shims;
  26 }
  27
  28 DiagnosticRequestHandle diagnostic_request(DiagnosticShims* shims,
  29         DiagnosticRequest* request, DiagnosticResponseReceived callback) {
  30     DiagnosticRequestHandle handle = {
  31         request: *request,
  32         callback: callback,
  33         success: false,
  34         completed: false
  35     };
  36
  37     uint8_t payload[MAX_DIAGNOSTIC_PAYLOAD_SIZE];
  38     payload[MODE_BYTE_INDEX] = request->mode;
  39     if(request->pid_length > 0) {
  40         // TODO need a set bit field that's more natural and checks endianness
  41         // becauase we DO need to flip it
  42         copy_bytes_right_aligned((uint8_t*)&request->pid, sizeof(request->pid),
  43                 PID_BYTE_INDEX, request->pid_length, payload, sizeof(payload));
  44     }
  45     if(request->payload_length > 0) {
  46         memcpy(&payload[PID_BYTE_INDEX + request->pid_length],
  47                 request->payload, request->payload_length);
  48     }
  49
  50     handle.isotp_shims = isotp_init_shims(shims->log,
  51             shims->send_can_message,
  52             shims->set_timer);
  53
  54     handle.isotp_send_handle = isotp_send(&handle.isotp_shims,
  55             request->arbitration_id, payload,
  56             1 + request->payload_length + request->pid_length,
  57             NULL);
  58     if(shims->log != NULL) {
  59         shims->log("Sending diagnostic request: arb_id: 0x%02x, mode: 0x%x, pid: 0x%x, payload: 0x%02x%02x%02x%02x%02x%02x%02x%02x, size: %d\r\n",
  60                 request->arbitration_id,
  61                 request->mode,
  62                 request->pid,
  63                 request->payload[0],
  64                 request->payload[1],
  65                 request->payload[2],
  66                 request->payload[3],
  67                 request->payload[4],
  68                 request->payload[5],
  69                 request->payload[6],
  70                 request->payload[7],
  71                 request->payload_length);
  72     }
  73
  74     handle.isotp_receive_handle = isotp_receive(&handle.isotp_shims,
  75             request->arbitration_id + ARBITRATION_ID_OFFSET,
  76             NULL);
  77
  78     // TODO notes on multi frame:
  79     // TODO what are the timers for exactly?
  80     //
  81     // when sending multi frame, send 1 frame, wait for a response
  82     // if it says send all, send all right away
  83     // if it says flow control, set the time for the next send
  84     // instead of creating a timer with an async callback, add a process_handle
  85     // function that's called repeatedly in the main loop - if it's time to
  86     // send, we do it. so there's a process_handle_send and receive_can_frame
  87     // that are just called continuously from the main loop. it's a waste of a
  88     // few cpu cycles but it may be more  natural than callbacks.
  89     //
  90     // what woudl a timer callback look like...it would need to pass the handle
  91     // and that's all. seems like a context void* would be able to capture all
  92     // of the information but arg, memory allocation. look at how it's done in
  93     // the other library again
  94     //
  95     return handle;
  96 }
  97
  98 DiagnosticRequestHandle diagnostic_request_pid(DiagnosticShims* shims,
  99         DiagnosticPidRequestType pid_request_type, uint16_t arbitration_id,
 100         uint16_t pid, DiagnosticResponseReceived callback) {
 101     DiagnosticRequest request = {
 102         arbitration_id: arbitration_id,
 103         mode: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 0x1 : 0x22,
 104         pid: pid,
 105         pid_length: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 1 : 2
 106     };
 107
 108     return diagnostic_request(shims, &request, callback);
 109 }
 110
 111 static bool handle_negative_response(IsoTpMessage* message,
 112         DiagnosticResponse* response, DiagnosticShims* shims) {
 113     bool response_was_negative = false;
 114     if(response->mode == NEGATIVE_RESPONSE_MODE) {
 115         response_was_negative = true;
 116         if(message->size > NEGATIVE_RESPONSE_MODE_INDEX) {
 117             response->mode = message->payload[NEGATIVE_RESPONSE_MODE_INDEX];
 118         }
 119
 120         if(message->size > NEGATIVE_RESPONSE_NRC_INDEX) {
 121             response->negative_response_code = message->payload[NEGATIVE_RESPONSE_NRC_INDEX];
 122         }
 123
 124         response->success = false;
 125         response->completed = true;
 126     }
 127     return response_was_negative;
 128 }
 129
 130 static bool handle_positive_response(DiagnosticRequestHandle* handle,
 131         IsoTpMessage* message, DiagnosticResponse* response,
 132         DiagnosticShims* shims) {
 133     bool response_was_positive = false;
 134     if(response->mode == handle->request.mode + MODE_RESPONSE_OFFSET) {
 135         response_was_positive = true;
 136         // hide the "response" version of the mode from the user
 137         // if it matched
 138         response->mode = handle->request.mode;
 139         if(handle->request.pid_length > 0 && message->size > 1) {
 140             if(handle->request.pid_length == 2) {
 141                 response->pid = *(uint16_t*)&message->payload[PID_BYTE_INDEX];
 142                 if(BYTE_ORDER == LITTLE_ENDIAN) {
 143                     response->pid = __builtin_bswap32(response->pid << 16);
 144                 }
 145             } else {
 146                 response->pid = message->payload[PID_BYTE_INDEX];
 147             }
 148         }
 149
 150         uint8_t payload_index = 1 + handle->request.pid_length;
 151         response->payload_length = message->size - payload_index;
 152         if(response->payload_length > 0) {
 153             memcpy(response->payload, &message->payload[payload_index],
 154                     response->payload_length);
 155         }
 156         response->success = true;
 157         response->completed = true;
 158     }
 159     return response_was_positive;
 160 }
 161
 162 DiagnosticResponse diagnostic_receive_can_frame(DiagnosticShims* shims,
 163         DiagnosticRequestHandle* handle, const uint16_t arbitration_id,
 164         const uint8_t data[], const uint8_t size) {
 165
 166     DiagnosticResponse response = {
 167         arbitration_id: arbitration_id,
 168         success: false,
 169         completed: false
 170     };
 171
 172     if(!handle->isotp_send_handle.completed) {
 173         isotp_continue_send(&handle->isotp_shims,
 174                 &handle->isotp_send_handle, arbitration_id, data, size);
 175     } else if(!handle->isotp_receive_handle.completed) {
 176         IsoTpMessage message = isotp_continue_receive(&handle->isotp_shims,
 177                 &handle->isotp_receive_handle, arbitration_id, data, size);
 178
 179         if(message.completed) {
 180             if(message.size > 0) {
 181                 response.mode = message.payload[0];
 182                 if(handle_negative_response(&message, &response, shims)) {
 183                     shims->log("Received a negative response to mode %d on arb ID 0x%x",
 184                             response.mode, response.arbitration_id);
 185                     handle->success = true;
 186                     handle->completed = true;
 187                 } else if(handle_positive_response(handle, &message, &response,
 188                             shims)) {
 189                     shims->log("Received a positive mode %d response on arb ID 0x%x",
 190                             response.mode, response.arbitration_id);
 191                     handle->success = true;
 192                     handle->completed = true;
 193                 } else {
 194                     shims->log("Response was for a mode 0x%x request, not our mode 0x%x request",
 195                             response.mode - MODE_RESPONSE_OFFSET,
 196                             handle->request.mode);
 197                 }
 198             }
 199
 200             if(handle->completed && handle->callback != NULL) {
 201                 handle->callback(&response);
 202             }
 203         }
 204
 205     } else {
 206         shims->log("Mode %d request to arb ID 0x%x is already completed",
 207                 handle->request.mode, handle->request.arbitration_id);
 208     }
 209     return response;
 210 }