Ref #1 Fix motorola data format

tests/README.md

@@ -0,0 +1,27 @@
+# Decoder regression tests
+
+Run from the repository root with a C++17 compiler:
+
+```sh
+g++ -std=c++17 -Wall -Wextra -Wpedantic -I. \
+  tests/dbc_decoder_test.cpp dbc_decoder.cpp -o /tmp/dbc_decoder_test
+/tmp/dbc_decoder_test
+```
+
+Alternatively, build the standalone qmake project out of source:
+
+```sh
+mkdir -p /tmp/dbc_decoder_test_build
+cd /tmp/dbc_decoder_test_build
+qmake /absolute/path/to/dbc/tests/dbc_decoder_test.pro
+make
+./dbc_decoder_test
+```
+
+The executable returns a nonzero exit code if any case fails. Checks remain
+active in release builds and do not depend on `assert` or an external test framework.
+
+Coverage includes Motorola bit numbering within and across bytes, unaligned
+signals, signed values, scaling, 64-bit extraction, invalid lengths, insufficient
+payloads, and Intel regression cases. Frame validity means the definition was
+found; insufficient payloads are checked through signal validity.

tests/dbc_decoder_test.cpp

@@ -0,0 +1,97 @@
+#include "dbc_decoder.h"
+
+#include <iostream>
+#include <limits>
+
+struct DecodeCase {
+  const char *name;
+  ByteOrder byteOrder;
+  std::uint32_t startBit;
+  std::uint32_t length;
+  ValueType valueType;
+  std::vector<std::uint8_t> data;
+  bool valid;
+  std::int64_t rawValue;
+  double factor;
+  double offset;
+  double physicalValue;
+};
+
+int main() {
+  const DecodeCase cases[] = {
+    {"Motorola reproduction", ByteOrder::Motorola, 7U, 16U, ValueType::Unsigned,
+     {0x12, 0x34}, true, 0x1234, 1.0, 0.0, 4660.0},
+    {"Motorola within byte", ByteOrder::Motorola, 5U, 4U, ValueType::Unsigned,
+     {0xAC}, true, 11, 1.0, 0.0, 11.0},
+    {"Motorola unaligned crossing", ByteOrder::Motorola, 3U, 12U, ValueType::Unsigned,
+     {0xAB, 0xCD}, true, 0xBCD, 1.0, 0.0, 3021.0},
+    {"Motorola starts at bit zero", ByteOrder::Motorola, 0U, 2U, ValueType::Unsigned,
+     {0x01, 0x80}, true, 3, 1.0, 0.0, 3.0},
+    {"Motorola second byte", ByteOrder::Motorola, 15U, 16U, ValueType::Unsigned,
+     {0xFF, 0x12, 0x34}, true, 0x1234, 1.0, 0.0, 4660.0},
+    {"Motorola signed scaled", ByteOrder::Motorola, 7U, 16U, ValueType::Signed,
+     {0xFF, 0xFE}, true, -2, 0.5, 10.0, 9.0},
+    {"Motorola 64 bits", ByteOrder::Motorola, 7U, 64U, ValueType::Unsigned,
+     {0, 0, 0, 0, 0, 0, 0x12, 0x34}, true, 0x1234, 1.0, 0.0, 4660.0},
+    {"Motorola 64 bits high bit", ByteOrder::Motorola, 7U, 64U, ValueType::Unsigned,
+     {0x40, 0, 0, 0, 0, 0, 0, 0}, true, 0x4000000000000000LL,
+     1.0, 0.0, 4611686018427387904.0},
+    {"Motorola short payload", ByteOrder::Motorola, 7U, 16U, ValueType::Unsigned,
+     {0x12}, false, 0, 1.0, 0.0, 0.0},
+    {"Motorola empty payload", ByteOrder::Motorola, 7U, 8U, ValueType::Unsigned,
+     {}, false, 0, 1.0, 0.0, 0.0},
+    {"Motorola large start", ByteOrder::Motorola,
+     std::numeric_limits<std::uint32_t>::max(), 8U, ValueType::Unsigned,
+     {0xFF}, false, 0, 1.0, 0.0, 0.0},
+    {"Motorola zero length", ByteOrder::Motorola, 7U, 0U, ValueType::Unsigned,
+     {0xFF}, false, 0, 1.0, 0.0, 0.0},
+    {"Motorola excessive length", ByteOrder::Motorola, 7U, 65U, ValueType::Unsigned,
+     std::vector<std::uint8_t> (9U, 0xFF), false, 0, 1.0, 0.0, 0.0},
+    {"Intel regression", ByteOrder::Intel, 0U, 16U, ValueType::Unsigned,
+     {0x12, 0x34}, true, 0x3412, 1.0, 0.0, 13330.0},
+    {"Intel signed regression", ByteOrder::Intel, 0U, 16U, ValueType::Signed,
+     {0xFE, 0xFF}, true, -2, 0.5, 10.0, 9.0},
+    {"Intel short payload", ByteOrder::Intel, 0U, 16U, ValueType::Unsigned,
+     {0x12}, false, 0, 1.0, 0.0, 0.0}
+  };
+
+  int failures = 0;
+  for (const DecodeCase &test : cases) {
+    DecodeSignal signal;
+    signal.name = test.name;
+    signal.byteOrder = test.byteOrder;
+    signal.startBit = test.startBit;
+    signal.length = test.length;
+    signal.valueType = test.valueType;
+    signal.factor = test.factor;
+    signal.offset = test.offset;
+
+    DecodeFrame definition;
+    definition.canId = 0x123U;
+    definition.dlc = static_cast<std::uint8_t> (test.data.size());
+    definition.signals.push_back (signal);
+    DecodeDatabase database;
+    database.frames.push_back (definition);
+    database.frameIndexByKey.emplace (FrameKey (definition.canId, false), 0U);
+
+    RawCanFrame frame;
+    frame.canId = definition.canId;
+    frame.data = test.data;
+    const DecodedFrameValue result = DbcDecoder().Decode (database, frame);
+    const bool passed = result.valid &&
+      (result.definition == &database.frames[0]) &&
+      (result.signals.size() == 1U) &&
+      (result.signals[0].definition == &database.frames[0].signals[0]) &&
+      (result.signals[0].valid == test.valid) &&
+      (!test.valid || ((result.signals[0].rawValue == test.rawValue) &&
+                      (result.signals[0].physicalValue == test.physicalValue)));
+    if (!passed) {
+      std::cerr << "FAIL: " << test.name << '\n';
+      ++failures;
+    }
+  }
+  if (failures != 0)
+    return 1;
+  std::cout << "All " << sizeof (cases) / sizeof (cases[0]) << " decoder cases passed.\n";
+  return 0;
+}

tests/dbc_decoder_test.pro

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+TEMPLATE = app
+TARGET = dbc_decoder_test
+CONFIG += console c++17
+CONFIG -= app_bundle qt
+INCLUDEPATH += ..
+SOURCES += dbc_decoder_test.cpp ../dbc_decoder.cpp
+HEADERS += ../dbc_decoder.h ../decode_database.h