feat(protocol): derive wire size and airtime at compile time

tests/arduino_stubs/Arduino.h

@@ -0,0 +1,50 @@
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+
+struct GPIO_TypeDef
+{
+    uint32_t BSRR = 0U;
+    uint32_t IDR = 0U;
+};
+
+using IRQn_Type = int;
+enum TimerFormat_t : uint8_t { TICK_FORMAT = 0, MICROSEC_FORMAT, HERTZ_FORMAT };
+
+constexpr uint8_t LOW = 0U;
+constexpr uint8_t HIGH = 1U;
+constexpr uint8_t INPUT = 0U;
+constexpr uint8_t OUTPUT = 1U;
+
+class HardwareTimer
+{
+public:
+    void pause() {}
+    void resume() {}
+    void setOverflow(uint32_t value, TimerFormat_t = TICK_FORMAT) { overflow_ = value; }
+    uint32_t getOverflow(TimerFormat_t = TICK_FORMAT) { return overflow_; }
+    uint32_t getPrescaleFactor() { return 1U; }
+    uint32_t getTimerClkFreq() { return 12000000U; }
+    void attachInterrupt(uint8_t, void (*)()) {}
+
+private:
+    uint32_t overflow_ = 1U;
+};
+
+inline GPIO_TypeDef *digitalPinToPort(uint8_t) { return nullptr; }
+inline uint16_t digitalPinToBitMask(uint8_t) { return 0U; }
+inline void pinMode(uint8_t, uint8_t) {}
+inline void digitalWrite(uint8_t, uint8_t) {}
+inline void NVIC_SetPriority(IRQn_Type, uint8_t) {}
+inline void noInterrupts() {}
+inline void interrupts() {}
+
+struct ArduinoSerialStub
+{
+    template <typename T> void print(const T &) {}
+    template <typename T> void println(const T &) {}
+    void println() {}
+};
+
+inline ArduinoSerialStub Serial;

tests/test_timing_contract.cpp

@@ -0,0 +1,85 @@
+#include "IR_Encoder.h"
+#include "IR_DecoderRaw.h"
+
+#include <array>
+#include <cassert>
+#include <cstdint>
+#include <iostream>
+
+// Link seams: these paths are not exercised by the pure host timing test.
+bool IR_DecoderRaw::registerPairMuteEncoder(IR_Encoder *) { return true; }
+void IR_DecoderRaw::refreshPairMuteState() {}
+void IR_Encoder::send_HIGH(bool) {}
+void IR_Encoder::send_LOW() {}
+void IR_Encoder::send_EMPTY(uint8_t) {}
+
+namespace
+{
+static_assert(irproto::dataWireBytes(0U) == 7U, "empty DATA wire size changed");
+static_assert(irproto::dataWireBytes(3U) == 10U, "DATA wire size changed");
+static_assert(irproto::dataWireBytes(24U) == 31U, "maximum DATA wire size changed");
+static_assert(irproto::dataWireBytes(25U) == 0U, "oversized DATA must be rejected");
+static_assert(irproto::backWireBytes(1U) == 6U, "BACK wire size changed");
+static_assert(irproto::backWireBytes(26U) == 31U, "maximum BACK wire size changed");
+static_assert(irproto::backToWireBytes(24U) == 31U, "maximum BACK_TO wire size changed");
+
+static_assert(irproto::wireLogicalTicks(6U) == 5472U, "6-byte tick count changed");
+static_assert(irproto::wireLogicalTicks(10U) == 8728U, "10-byte tick count changed");
+static_assert(irproto::wireLogicalTicks(31U) == 25822U, "31-byte tick count changed");
+static_assert(irproto::preambleAirtimeUsCeil() == 7737U, "preamble airtime changed");
+static_assert(irproto::wireAirtimeUsCeil(6U) == 72000U, "6-byte airtime changed");
+static_assert(irproto::wireAirtimeUsCeil(10U) == 114843U, "10-byte airtime changed");
+static_assert(irproto::wireAirtimeUsCeil(31U) == 339764U, "31-byte airtime changed");
+static_assert(irproto::responseStartGuardUs() == 57198U, "response-start guard changed");
+static_assert(irproto::responseFrameGuardUs(6U) == 131100U, "response-frame guard changed");
+
+uint32_t sumLogicalTicks(const IrTxGateRun *runs, size_t count)
+{
+    uint32_t total = 0U;
+    for (size_t i = 0U; i < count; ++i)
+        total += runs[i].lenTicks;
+    return total;
+}
+
+void verifyFormulaAgainstTxFsm()
+{
+    std::array<uint8_t, irproto::kMaxWireFrameBytes> frame{};
+    std::array<IrTxGateRun, 1024U> runs{};
+
+    for (uint8_t wireBytes = 1U; wireBytes <= irproto::kMaxWireFrameBytes; ++wireBytes)
+    {
+        for (uint8_t pattern = 0U; pattern < 4U; ++pattern)
+        {
+            for (uint8_t i = 0U; i < wireBytes; ++i)
+            {
+                frame[i] = pattern == 0U ? 0x00U
+                         : pattern == 1U ? 0xFFU
+                         : pattern == 2U ? static_cast<uint8_t>((i & 1U) ? 0x55U : 0xAAU)
+                                         : static_cast<uint8_t>(i * 73U + 19U);
+            }
+            const size_t count = IR_Encoder::buildGateRuns(
+                frame.data(), wireBytes, runs.data(), runs.size());
+            assert(count != 0U);
+            assert(sumLogicalTicks(runs.data(), count) == irproto::wireLogicalTicks(wireBytes));
+        }
+    }
+}
+
+void verifyPublicSendTimeResults()
+{
+    IR_Encoder encoder(1U, 42U, nullptr, false);
+    uint8_t payload[26]{};
+
+    assert(encoder.testSendAccept(1U) == 72U);              // six-byte wire frame
+    assert(encoder.testSendTime(1U, payload, 3U) == 115U); // ten-byte wire frame
+    assert(encoder.testSendBack(payload, 26U) == 340U);    // 31-byte wire frame
+}
+}
+
+int main()
+{
+    verifyFormulaAgainstTxFsm();
+    verifyPublicSendTimeResults();
+    std::cout << "IR timing contract tests: OK\n";
+    return 0;
+}