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 #ifndef MAX
  18 #define MAX(x, y) (((x) > (y)) ? (x) : (y))
  19 #endif
  20
  21 DiagnosticShims diagnostic_init_shims(LogShim log,
  22         SendCanMessageShim send_can_message,
  23         SetTimerShim set_timer) {
  24     DiagnosticShims shims = {
  25         log: log,
  26         send_can_message: send_can_message,
  27         set_timer: set_timer
  28     };
  29     return shims;
  30 }
  31
  32 static void setup_receive_handle(DiagnosticRequestHandle* handle) {
  33     if(handle->request.arbitration_id == OBD2_FUNCTIONAL_BROADCAST_ID) {
  34         uint16_t response_id;
  35         for(response_id = 0;
  36                 response_id < OBD2_FUNCTIONAL_RESPONSE_COUNT; ++response_id) {
  37             handle->isotp_receive_handles[response_id] = isotp_receive(
  38                     &handle->isotp_shims, OBD2_FUNCTIONAL_RESPONSE_START + response_id,
  39                     NULL);
  40         }
  41         handle->isotp_receive_handle_count = OBD2_FUNCTIONAL_RESPONSE_COUNT;
  42     } else {
  43         handle->isotp_receive_handle_count = 1;
  44         handle->isotp_receive_handles[0] = isotp_receive(&handle->isotp_shims,
  45                 handle->request.arbitration_id + ARBITRATION_ID_OFFSET,
  46                 NULL);
  47     }
  48 }
  49
  50
  51 DiagnosticRequestHandle diagnostic_request(DiagnosticShims* shims,
  52         DiagnosticRequest* request, DiagnosticResponseReceived callback) {
  53     DiagnosticRequestHandle handle = {
  54         request: *request,
  55         callback: callback,
  56         success: false,
  57         completed: false
  58     };
  59
  60     uint8_t payload[MAX_DIAGNOSTIC_PAYLOAD_SIZE] = {0};
  61     payload[MODE_BYTE_INDEX] = request->mode;
  62     if(request->pid_length > 0) {
  63         set_bitfield(request->pid, PID_BYTE_INDEX * CHAR_BIT,
  64                 request->pid_length * CHAR_BIT, payload, sizeof(payload));
  65     }
  66     if(request->payload_length > 0) {
  67         memcpy(&payload[PID_BYTE_INDEX + request->pid_length],
  68                 request->payload, request->payload_length);
  69     }
  70
  71     handle.isotp_shims = isotp_init_shims(shims->log,
  72             shims->send_can_message,
  73             shims->set_timer);
  74
  75     handle.isotp_send_handle = isotp_send(&handle.isotp_shims,
  76             request->arbitration_id, payload,
  77             1 + request->payload_length + request->pid_length,
  78             NULL);
  79     if(shims->log != NULL) {
  80         shims->log("Sending diagnostic request: arb_id: 0x%02x, mode: 0x%x, pid: 0x%x, payload: 0x%02x%02x%02x%02x%02x%02x%02x, size: %d\r\n",
  81                 request->arbitration_id,
  82                 request->mode,
  83                 request->pid,
  84                 request->payload[0],
  85                 request->payload[1],
  86                 request->payload[2],
  87                 request->payload[3],
  88                 request->payload[4],
  89                 request->payload[5],
  90                 request->payload[6],
  91                 request->payload_length);
  92     }
  93
  94     setup_receive_handle(&handle);
  95
  96     // TODO notes on multi frame:
  97     // TODO what are the timers for exactly?
  98     //
  99     // when sending multi frame, send 1 frame, wait for a response
 100     // if it says send all, send all right away
 101     // if it says flow control, set the time for the next send
 102     // instead of creating a timer with an async callback, add a process_handle
 103     // function that's called repeatedly in the main loop - if it's time to
 104     // send, we do it. so there's a process_handle_send and receive_can_frame
 105     // that are just called continuously from the main loop. it's a waste of a
 106     // few cpu cycles but it may be more  natural than callbacks.
 107     //
 108     // what woudl a timer callback look like...it would need to pass the handle
 109     // and that's all. seems like a context void* would be able to capture all
 110     // of the information but arg, memory allocation. look at how it's done in
 111     // the other library again
 112     //
 113     return handle;
 114 }
 115
 116 DiagnosticRequestHandle diagnostic_request_pid(DiagnosticShims* shims,
 117         DiagnosticPidRequestType pid_request_type, uint16_t arbitration_id,
 118         uint16_t pid, DiagnosticResponseReceived callback) {
 119     DiagnosticRequest request = {
 120         arbitration_id: arbitration_id,
 121         mode: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 0x1 : 0x22,
 122         pid: pid,
 123         pid_length: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 1 : 2
 124     };
 125
 126     return diagnostic_request(shims, &request, callback);
 127 }
 128
 129 static bool handle_negative_response(IsoTpMessage* message,
 130         DiagnosticResponse* response, DiagnosticShims* shims) {
 131     bool response_was_negative = false;
 132     if(response->mode == NEGATIVE_RESPONSE_MODE) {
 133         response_was_negative = true;
 134         if(message->size > NEGATIVE_RESPONSE_MODE_INDEX) {
 135             response->mode = message->payload[NEGATIVE_RESPONSE_MODE_INDEX];
 136         }
 137
 138         if(message->size > NEGATIVE_RESPONSE_NRC_INDEX) {
 139             response->negative_response_code = message->payload[NEGATIVE_RESPONSE_NRC_INDEX];
 140         }
 141
 142         response->success = false;
 143         response->completed = true;
 144     }
 145     return response_was_negative;
 146 }
 147
 148 static bool handle_positive_response(DiagnosticRequestHandle* handle,
 149         IsoTpMessage* message, DiagnosticResponse* response,
 150         DiagnosticShims* shims) {
 151     bool response_was_positive = false;
 152     if(response->mode == handle->request.mode + MODE_RESPONSE_OFFSET) {
 153         response_was_positive = true;
 154         // hide the "response" version of the mode from the user
 155         // if it matched
 156         response->mode = handle->request.mode;
 157         bool has_pid = false;
 158         if(handle->request.pid_length > 0 && message->size > 1) {
 159             has_pid = true;
 160             if(handle->request.pid_length == 2) {
 161                 response->pid = get_bitfield(message->payload, message->size,
 162                         PID_BYTE_INDEX * CHAR_BIT, sizeof(uint16_t) * CHAR_BIT);
 163             } else {
 164                 response->pid = message->payload[PID_BYTE_INDEX];
 165             }
 166
 167         }
 168
 169         uint8_t payload_index = 1 + handle->request.pid_length;
 170         response->payload_length = MAX(0, message->size - payload_index);
 171         if(response->payload_length > 0) {
 172             memcpy(response->payload, &message->payload[payload_index],
 173                     response->payload_length);
 174         }
 175
 176         if((handle->request.pid_length == 0 && !has_pid)
 177                 || response->pid == handle->request.pid) {
 178             response->success = true;
 179             response->completed = true;
 180         } else {
 181             response_was_positive = false;
 182         }
 183     }
 184     return response_was_positive;
 185 }
 186
 187 DiagnosticResponse diagnostic_receive_can_frame(DiagnosticShims* shims,
 188         DiagnosticRequestHandle* handle, const uint16_t arbitration_id,
 189         const uint8_t data[], const uint8_t size) {
 190
 191     DiagnosticResponse response = {
 192         arbitration_id: arbitration_id,
 193         success: false,
 194         completed: false
 195     };
 196
 197     if(!handle->isotp_send_handle.completed) {
 198         isotp_continue_send(&handle->isotp_shims,
 199                 &handle->isotp_send_handle, arbitration_id, data, size);
 200     } else {
 201         uint8_t i;
 202         for(i = 0; i < handle->isotp_receive_handle_count; ++i) {
 203             IsoTpMessage message = isotp_continue_receive(&handle->isotp_shims,
 204                     &handle->isotp_receive_handles[i], arbitration_id, data, size);
 205
 206             // TODO as of now we're completing the handle as soon as one
 207             // broadcast response is received....need to hang on for 100ms
 208             if(message.completed) {
 209                 if(message.size > 0) {
 210                     response.mode = message.payload[0];
 211                     if(handle_negative_response(&message, &response, shims)) {
 212                         shims->log("Received a negative response to mode %d on arb ID 0x%x",
 213                                 response.mode, response.arbitration_id);
 214                         handle->success = true;
 215                         handle->completed = true;
 216                     } else if(handle_positive_response(handle, &message, &response,
 217                                 shims)) {
 218                         shims->log("Received a positive mode %d response on arb ID 0x%x",
 219                                 response.mode, response.arbitration_id);
 220                         handle->success = true;
 221                         handle->completed = true;
 222                     } else {
 223                         shims->log("Response was for a mode 0x%x request (pid 0x%x), not our mode 0x%x request (pid 0x%x)",
 224                                 MAX(0, response.mode - MODE_RESPONSE_OFFSET),
 225                                 response.pid, handle->request.mode,
 226                                 handle->request.pid);
 227                         // TODO just leave handles open until the user decides
 228                         // to be done with it - keep a count of valid responses
 229                         // received.
 230                     }
 231                 } else {
 232                     shims->log("Received an empty response on arb ID 0x%x",
 233                             response.arbitration_id);
 234                 }
 235
 236                 if(handle->completed && handle->callback != NULL) {
 237                     handle->callback(&response);
 238                 }
 239             }
 240         }
 241     }
 242     return response;
 243 }