WIP: ocelot checksums

RetroPilot · Oct 10, 2023 · adf9f6c · adf9f6c
1 parent 647fb8a
commit adf9f6c
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Showing 5 changed files with 25 additions and 0 deletions.
diff --git a/can/common.cc b/can/common.cc
@@ -244,3 +244,21 @@ unsigned int hkg_can_fd_checksum(uint32_t address, const Signal &sig, const std:
 
   return crc;
 }
+
+unsigned int ocelot_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d) {
+  uint8_t crc = 0xFF;
+  uint8_t poly = 0x1D; // standard crc8
+
+  // skip checksum byte
+  for (int i = 1; i < d.size(); i++) {
+    crc ^= d[i];
+    for (int j = 0; j < 8; j++) {
+      if ((crc & 0x80) != 0) {
+        crc = (uint8_t)((crc << 1) ^ poly);
+      } else {
+        crc <<= 1;
+      }
+    }
+  }
+  return crc;
+}
diff --git a/can/common.h b/can/common.h
@@ -34,6 +34,7 @@ unsigned int volkswagen_mqb_checksum(uint32_t address, const Signal &sig, const
 unsigned int xor_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d);
 unsigned int hkg_can_fd_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d);
 unsigned int pedal_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d);
+unsigned int ocelot_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d);
 
 class MessageState {
 public:

diff --git a/can/common.pxd b/can/common.pxd
@@ -22,6 +22,8 @@ cdef extern from "common_dbc.h":
     SUBARU_CHECKSUM,
     CHRYSLER_CHECKSUM
     HKG_CAN_FD_CHECKSUM,
+    OCELOT_CHECKSUM,
+    OCELOT_COUNTER,
 
   cdef struct Signal:
     string name

diff --git a/can/common_dbc.h b/can/common_dbc.h
@@ -29,6 +29,8 @@ enum SignalType {
   SUBARU_CHECKSUM,
   CHRYSLER_CHECKSUM,
   HKG_CAN_FD_CHECKSUM,
+  OCELOT_CHECKSUM,
+  OCELOT_COUNTER,
 };
 
 struct Signal {

diff --git a/can/dbc.cc b/can/dbc.cc
@@ -67,6 +67,8 @@ ChecksumState* get_checksum(const std::string& dbc_name) {
     s = new ChecksumState({8, -1, 7, -1, false, CHRYSLER_CHECKSUM, &chrysler_checksum});
   } else if (startswith(dbc_name, "comma_body")) {
     s = new ChecksumState({8, 4, 7, 3, false, PEDAL_CHECKSUM, &pedal_checksum});
+  } else if (startswith(dbc_name, "ocelot_")) {
+    s = new ChecksumState({8, 4, 0, 0, true, OCELOT_CHECKSUM, &ocelot_checksum});
   }
   return s;
 }