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VW MQB: Refactored CRC calculation #1236

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merged 15 commits into from
Sep 13, 2024
Merged

VW MQB: Refactored CRC calculation #1236

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6a22559
VW MQB: Refactor CRC constants
JaCzekanski Sep 11, 2024
b5a733d
Merge branch 'master' of https://github.com/commaai/opendbc into vw_m…
jyoung8607 Sep 12, 2024
06d8f46
temporary, repeat packing step 1M times
jyoung8607 Sep 12, 2024
de421f0
follow comma convention for include order
jyoung8607 Sep 12, 2024
0656b91
comma indent convention, tighten message annotations
jyoung8607 Sep 12, 2024
326b088
whitespace
jyoung8607 Sep 12, 2024
b215a21
cleanup
jyoung8607 Sep 12, 2024
2df63eb
more comma indent convention
jyoung8607 Sep 12, 2024
b9fd909
Revert "temporary, repeat packing step 1M times"
jyoung8607 Sep 12, 2024
a957ee4
comment touch-up
jyoung8607 Sep 12, 2024
561bbd7
beautify spacing
jyoung8607 Sep 12, 2024
00e8552
codespell says you're gonna have to Google it
jyoung8607 Sep 12, 2024
98b3385
fully initialize all data ID arrays
jyoung8607 Sep 12, 2024
844f051
clarify array name as part of VW support
jyoung8607 Sep 12, 2024
34d2a3a
fix comment typo
jyoung8607 Sep 13, 2024
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104 changes: 35 additions & 69 deletions opendbc/can/common.cc
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
#include "opendbc/can/common.h"
#include <array>
#include <unordered_map>

#include "opendbc/can/common.h"

unsigned int honda_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d) {
int s = 0;
Expand Down Expand Up @@ -112,85 +114,49 @@ struct CrcInitializer {

static CrcInitializer crcInitializer;

static const std::unordered_map<uint32_t, std::array<uint8_t, 16>> volkswagen_mqb_crc_constants {
{0x86, {0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86}}, // LWI_01
{0x9F, {0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5}}, // LH_EPS_03
{0xAD, {0x3F, 0x69, 0x39, 0xDC, 0x94, 0xF9, 0x14, 0x64, 0xD8, 0x6A, 0x34, 0xCE, 0xA2, 0x55, 0xB5, 0x2C}}, // Getriebe_11
{0xFD, {0xB4, 0xEF, 0xF8, 0x49, 0x1E, 0xE5, 0xC2, 0xC0, 0x97, 0x19, 0x3C, 0xC9, 0xF1, 0x98, 0xD6, 0x61}}, // ESP_21
{0x106, {0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07}}, // ESP_05
{0x117, {0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16}}, // ACC_10
{0x120, {0xC4, 0xE2, 0x4F, 0xE4, 0xF8, 0x2F, 0x56, 0x81, 0x9F, 0xE5, 0x83, 0x44, 0x05, 0x3F, 0x97, 0xDF}}, // TSK_06
{0x121, {0xE9, 0x65, 0xAE, 0x6B, 0x7B, 0x35, 0xE5, 0x5F, 0x4E, 0xC7, 0x86, 0xA2, 0xBB, 0xDD, 0xEB, 0xB4}}, // Motor_20
{0x122, {0x37, 0x7D, 0xF3, 0xA9, 0x18, 0x46, 0x6D, 0x4D, 0x3D, 0x71, 0x92, 0x9C, 0xE5, 0x32, 0x10, 0xB9}}, // ACC_06
{0x126, {0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA}}, // HCA_01
{0x12B, {0x6A, 0x38, 0xB4, 0x27, 0x22, 0xEF, 0xE1, 0xBB, 0xF8, 0x80, 0x84, 0x49, 0xC7, 0x9E, 0x1E, 0x2B}}, // GRA_ACC_01
{0x12E, {0xF8, 0xE5, 0x97, 0xC9, 0xD6, 0x07, 0x47, 0x21, 0x66, 0xDD, 0xCF, 0x6F, 0xA1, 0x94, 0x74, 0x63}}, // ACC_07
{0x187, {0x7F, 0xED, 0x17, 0xC2, 0x7C, 0xEB, 0x44, 0x21, 0x01, 0xFA, 0xDB, 0x15, 0x4A, 0x6B, 0x23, 0x05}}, // Motor_EV_01
{0x30C, {0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F}}, // ACC_02
{0x30F, {0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C}}, // SWA_01
{0x324, {0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27}}, // ACC_04
{0x3C0, {0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3}}, // Klemmen_Status_01
{0x65D, {0xAC, 0xB3, 0xAB, 0xEB, 0x7A, 0xE1, 0x3B, 0xF7, 0x73, 0xBA, 0x7C, 0x9E, 0x06, 0x5F, 0x02, 0xD9}}, // ESP_20
};

unsigned int volkswagen_mqb_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d) {
// Volkswagen uses standard CRC8 8H2F/AUTOSAR, but they compute it with
// a magic variable padding byte tacked onto the end of the payload.
// https://www.autosar.org/fileadmin/user_upload/standards/classic/4-3/AUTOSAR_SWS_CRCLibrary.pdf
// This is AUTOSAR E2E Profile 2, CRC-8H2F with a "data ID" (varying by message/counter) appended to the payload

uint8_t crc = 0xFF; // Standard init value for CRC8 8H2F/AUTOSAR
uint8_t crc = 0xFF; // CRC-8H2F initial value

// CRC the payload first, skipping over the first byte where the CRC lives.
// CRC over payload first, skipping the first byte where the CRC lives
for (int i = 1; i < d.size(); i++) {
crc ^= d[i];
crc = crc8_lut_8h2f[crc];
}

// Look up and apply the magic final CRC padding byte, which permutes by CAN
// address, and additionally (for SOME addresses) by the message counter.
// Continue CRC over the "data ID"
uint8_t counter = d[1] & 0x0F;
switch (address) {
case 0x86: // LWI_01 Steering Angle
crc ^= (uint8_t[]){0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86}[counter];
break;
case 0x9F: // LH_EPS_03 Electric Power Steering
crc ^= (uint8_t[]){0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5, 0xF5}[counter];
break;
case 0xAD: // Getriebe_11 Automatic Gearbox
crc ^= (uint8_t[]){0x3F, 0x69, 0x39, 0xDC, 0x94, 0xF9, 0x14, 0x64, 0xD8, 0x6A, 0x34, 0xCE, 0xA2, 0x55, 0xB5, 0x2C}[counter];
break;
case 0xFD: // ESP_21 Electronic Stability Program
crc ^= (uint8_t[]){0xB4, 0xEF, 0xF8, 0x49, 0x1E, 0xE5, 0xC2, 0xC0, 0x97, 0x19, 0x3C, 0xC9, 0xF1, 0x98, 0xD6, 0x61}[counter];
break;
case 0x106: // ESP_05 Electronic Stability Program
crc ^= (uint8_t[]){0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07}[counter];
break;
case 0x117: // ACC_10 Automatic Cruise Control
crc ^= (uint8_t[]){0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16, 0x16}[counter];
break;
case 0x120: // TSK_06 Drivetrain Coordinator
crc ^= (uint8_t[]){0xC4, 0xE2, 0x4F, 0xE4, 0xF8, 0x2F, 0x56, 0x81, 0x9F, 0xE5, 0x83, 0x44, 0x05, 0x3F, 0x97, 0xDF}[counter];
break;
case 0x121: // Motor_20 Driver Throttle Inputs
crc ^= (uint8_t[]){0xE9, 0x65, 0xAE, 0x6B, 0x7B, 0x35, 0xE5, 0x5F, 0x4E, 0xC7, 0x86, 0xA2, 0xBB, 0xDD, 0xEB, 0xB4}[counter];
break;
case 0x122: // ACC_06 Automatic Cruise Control
crc ^= (uint8_t[]){0x37, 0x7D, 0xF3, 0xA9, 0x18, 0x46, 0x6D, 0x4D, 0x3D, 0x71, 0x92, 0x9C, 0xE5, 0x32, 0x10, 0xB9}[counter];
break;
case 0x126: // HCA_01 Heading Control Assist
crc ^= (uint8_t[]){0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA}[counter];
break;
case 0x12B: // GRA_ACC_01 Steering wheel controls for ACC
crc ^= (uint8_t[]){0x6A, 0x38, 0xB4, 0x27, 0x22, 0xEF, 0xE1, 0xBB, 0xF8, 0x80, 0x84, 0x49, 0xC7, 0x9E, 0x1E, 0x2B}[counter];
break;
case 0x12E: // ACC_07 Automatic Cruise Control
crc ^= (uint8_t[]){0xF8, 0xE5, 0x97, 0xC9, 0xD6, 0x07, 0x47, 0x21, 0x66, 0xDD, 0xCF, 0x6F, 0xA1, 0x94, 0x74, 0x63}[counter];
break;
case 0x187: // Motor_EV_01 gearshift position for BEVs with no transmission
crc ^= (uint8_t[]){0x7F, 0xED, 0x17, 0xC2, 0x7C, 0xEB, 0x44, 0x21, 0x01, 0xFA, 0xDB, 0x15, 0x4A, 0x6B, 0x23, 0x05}[counter];
break;
case 0x30C: // ACC_02 Automatic Cruise Control
crc ^= (uint8_t[]){0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F}[counter];
break;
case 0x30F: // SWA_01 Lane Change Assist (SpurWechselAssistent)
crc ^= (uint8_t[]){0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C}[counter];
break;
case 0x324: // ACC_04 Automatic Cruise Control
crc ^= (uint8_t[]){0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27, 0x27}[counter];
break;
case 0x3C0: // Klemmen_Status_01 ignition and starting status
crc ^= (uint8_t[]){0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3}[counter];
break;
case 0x65D: // ESP_20 Electronic Stability Program
crc ^= (uint8_t[]){0xAC, 0xB3, 0xAB, 0xEB, 0x7A, 0xE1, 0x3B, 0xF7, 0x73, 0xBA, 0x7C, 0x9E, 0x06, 0x5F, 0x02, 0xD9}[counter];
break;
default: // As-yet undefined CAN message, CRC check expected to fail
printf("Attempt to CRC check undefined Volkswagen message 0x%02X\n", address);
crc ^= (uint8_t[]){0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}[counter];
break;
auto crc_const = volkswagen_mqb_crc_constants.find(address);
if (crc_const != volkswagen_mqb_crc_constants.end()) {
crc ^= crc_const->second[counter];
crc = crc8_lut_8h2f[crc];
} else {
printf("Attempt to CRC check undefined Volkswagen message 0x%02X\n", address);
}
crc = crc8_lut_8h2f[crc];

return crc ^ 0xFF; // Return after standard final XOR for CRC8 8H2F/AUTOSAR
return crc ^ 0xFF; // CRC-8H2F final XOR
}

unsigned int xor_checksum(uint32_t address, const Signal &sig, const std::vector<uint8_t> &d) {
Expand Down
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