AutoResearchLowMemory.h

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#pragma once
//
// examples/AutoResearch/AutoResearchLowMemory.h
//
// Low-memory AutoResearch bring-up surface for parts whose flash budget
// cannot fit the full ESP32 / Teensy LED-protocol matrix. Originally lived
// as the standalone `examples/AutoResearchLpc/AutoResearchLpc.ino` sketch;
// retired and folded in here per FastLED #3030 once the soft-FP cascade
// from #3022 phase 2 freed up the budget on LPC8xx.
//
// Included from the main `AutoResearch.ino` when
// `FL_PLATFORM_HAS_LARGE_MEMORY == 0` (Low + Tiny tiers per the FastLED
// #3000 memory classification).
//
// Same JSON-RPC contract as the retired LPC sketch:
//   echo: [int] -> int
//   pinToggleRx: [tx_pin, rx_pin, freq_hz, duration_ms] -> CSV
//   ws2812SctTest: [test_case, tx_pin, rx_pin, capture_ms] -> CSV
// See FastLED #3021 for the SCT-RX bring-up flags.
//
 
#include "platforms/arm/lpc/is_lpc.h"  // ok platform headers - LPC RX driver gate
 
// Gate FL_DBG to no-op. Without `RELEASE`, fl/log/log.h auto-sets
// FASTLED_FORCE_DBG=1, which expands every FL_DBG call site (inside
// fl::Remote etc.) through the fl::println formatting machinery and
// blows ~4 KB of flash budget. fbuild's nxplpc orchestrator does not
// yet propagate platformio.ini's `build_flags`, so it's defined here.
#ifndef RELEASE
#define RELEASE 1
#endif
 
// Dedicated #3039 codec-test builds keep the low-memory surface to echo +
// IEEE754 only. The SCT/WS2812 handlers are useful diagnostics, but they are
// unrelated to the codec and push LPC845 past its flash budget when combined.
#if defined(FL_AUTORESEARCH_IEEE754) && FL_AUTORESEARCH_IEEE754
#define FASTLED_AUTORESEARCH_IEEE754_MODE 1
#endif
 
// ESP8266 has 4 MB of flash but too little DRAM for the full harness, so its
// low-memory build always carries the IEEE754 codec check next to echo.
#include "platforms/esp/is_esp.h"  // ok platform headers // ok platform specific - ESP8266 surface gate
#if defined(FL_IS_ESP8266) && !defined(FASTLED_AUTORESEARCH_IEEE754_MODE)  // ok platform specific - ESP8266 low-DRAM build always carries IEEE754 check
#define FASTLED_AUTORESEARCH_IEEE754_MODE 1
#endif
// The clockless bench reports the driver's frame/retry counters.
#if defined(FL_IS_ESP8266) && !defined(FASTLED_DEBUG_COUNT_FRAME_RETRIES)  // ok platform specific - clockless bench reads ESP8266 retry counters
#define FASTLED_DEBUG_COUNT_FRAME_RETRIES 1
#endif
 
#if !defined(FASTLED_AUTORESEARCH_LPC_UART_DMA)
#define FASTLED_AUTORESEARCH_LPC_UART_DMA 0
#endif
 
// Opt in to the SCT input-capture RX backend (FastLED #3021). With this
// flag set, `LpcSctRxChannel::begin()` programs the SCT for hardware
// edge-capture; without it the driver is a no-op stub (host tests still
// work via `injectEdges()`).
#if !defined(FASTLED_AUTORESEARCH_IEEE754_MODE) && \
    !defined(FASTLED_AUTORESEARCH_FAULT_TEST)
#ifndef FASTLED_LPC_RX_SCT
#define FASTLED_LPC_RX_SCT 1
#endif
#endif
 
// The LPC845-BRK low-memory build fits FastLED + Remote + the WS2812 loopback
// RPC in normal mode. The dedicated IEEE754 mode deliberately omits it.
#if defined(FL_IS_ARM_LPC_845) && !defined(FASTLED_AUTORESEARCH_IEEE754_MODE) && \
    !defined(FASTLED_AUTORESEARCH_FAULT_TEST) && !defined(FASTLED_LPC_SPI_DMA) && \
    !defined(FASTLED_LPC_PWM_DMA) && !FASTLED_AUTORESEARCH_LPC_UART_DMA
#define FASTLED_AUTORESEARCH_LPC_WS2812 1
#endif
 
// The WS2812 loopback uses the SCT->DMA RX capture path. The UART clockless
// verifier uses USART RX-DMA instead, so keep SCT-DMA out of that build;
// UM11029 Table 296 fixes USART1_RX/USART1_TX on DMA channels 2/3.
#if defined(FASTLED_AUTORESEARCH_LPC_WS2812) && \
    !defined(FASTLED_LPC_RX_SCT_DMA)
#define FASTLED_LPC_RX_SCT_DMA 1
#endif
 
#include <Arduino.h>
#include "fl/remote/remote.h"
#include "fl/remote/transport/serial.h"
#include "fl/stl/compiler_control.h"
#include "fl/wdt/watchdog.h"
#include "fl/log/log.h"
#include "fl/stl/cstdio.h"  // fl::serial_begin -- HWCDC-safe Serial.begin wrapper
#include "fl/stl/singleton.h"
 
#if defined(FASTLED_AUTORESEARCH_IEEE754_MODE)
#include "AutoResearchIeee754.h"
#endif
 
// The host-stub example DLL build (`tests/shared/example_dll_wrapper_template.cpp`)
// compiles this sketch on Linux to surface ABI breaks. The RX SCT driver
// types are platform-gated behind `FL_IS_ARM_LPC` -- they only exist on
// the real LPC build. So the include + every RX usage below must be gated
// the same way.
#if defined(FL_IS_ARM_LPC) && !defined(FASTLED_AUTORESEARCH_IEEE754_MODE) && \
    !defined(FASTLED_AUTORESEARCH_FAULT_TEST)
#include "fl/channels/rx_sct_capture.h"
#include "fl/stl/strstream.h"
#endif
 
#if defined(FASTLED_AUTORESEARCH_LPC_WS2812)
#include "FastLED.h"
#include "fl/chipsets/timing_traits.h"
#endif
 
// FastLED #3468: channels-API SCT+DMA clockless AutoResearch harness.
// Opt-in via `-DFASTLED_LPC_PWM_DMA=1`; the header self-gates on
// `FL_IS_ARM_LPC_845 && FASTLED_LPC_PWM_DMA` so unrelated builds are
// unaffected. Note: exclusive with FASTLED_AUTORESEARCH_LPC_WS2812 —
// both target the same SCT peripheral and would collide at runtime.
// The host-side `bash autoresearch --pwm-dma-cl` wrapper enforces
// mutual exclusion with `--dma-spi` and the legacy `ws2812SctTest`.
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_LPC_PWM_DMA)
#include "AutoResearchPwmDmaClockless.h"
#endif
 
// FastLED #3456: LPC845 SPI+DMA async AutoResearch harness (Phase 1 of
// #3453 bench bring-up). Opt-in via `-DFASTLED_LPC_SPI_DMA=1`; the
// header self-gates on `FL_IS_ARM_LPC_845 && FASTLED_LPC_SPI_DMA`.
// LPC804 is NOT supported — silicon has no DMA peripheral. See
// `agents/docs/peripheral-existence.md`. Mutually exclusive with
// FASTLED_LPC_PWM_DMA (both claim DMA0 channels and the LowMemory
// flash budget doesn't fit both). Enforced host-side by
// `bash autoresearch` refusing `--dma-spi --pwm-dma-cl`.
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_LPC_SPI_DMA) && \
    defined(FASTLED_LPC_PWM_DMA)
#error "FASTLED_LPC_SPI_DMA and FASTLED_LPC_PWM_DMA are mutually exclusive on LPC845: both claim DMA0 channels and the LowMemory flash budget doesn't fit both. Pick one for the AutoResearch build."
#endif
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_LPC_SPI_DMA)
#include "AutoResearchSpiDma.h"
#endif
 
// #3453 follow-up: LPC845 async UART TX harness (DMA + ISR chunk chain) and
// #3611 UART clockless loopback verifier. The UART DMA driver is now the
// LPC845 library default, so the AutoResearch RPC harness has its own flag.
#if defined(FL_IS_ARM_LPC_845) && FASTLED_AUTORESEARCH_LPC_UART_DMA && \
    !FASTLED_LPC_UART_DMA
#error "FASTLED_AUTORESEARCH_LPC_UART_DMA requires FASTLED_LPC_UART_DMA=1."
#endif
#if defined(FL_IS_ARM_LPC_845) && FASTLED_AUTORESEARCH_LPC_UART_DMA && \
    (defined(FASTLED_LPC_SPI_DMA) || defined(FASTLED_LPC_PWM_DMA))
#error "FASTLED_AUTORESEARCH_LPC_UART_DMA is mutually exclusive with the SPI/PWM DMA harnesses on LPC845: the LowMemory flash budget fits one bench at a time. Pick one for the AutoResearch build."
#endif
#if defined(FL_IS_ARM_LPC_845) && FASTLED_AUTORESEARCH_LPC_UART_DMA
#include "AutoResearchUartDma.h"
#endif
 
// ESP8266 UART WS2812 driver benches (pad self-capture, no jumper needed).
#if defined(FL_IS_ESP8266)  // ok platform specific - ESP8266 bring-up benches
#include "AutoResearchEsp8266.h"
#endif
 
namespace autoresearch {
namespace low_memory {
 
struct RemoteState {
    fl::Remote remote;
 
    RemoteState()
        : remote(fl::createSerialRequestSource(),
                 fl::createSerialResponseSink("REMOTE: ")) {}
};
 
inline RemoteState& remoteState() {
    return fl::SingletonShared<RemoteState>::instance();
}
 
#if defined(FL_IS_ARM_LPC) && !defined(FASTLED_AUTORESEARCH_IEEE754_MODE) && \
    !defined(FASTLED_AUTORESEARCH_FAULT_TEST)
struct PinToggleState {
    fl::EdgeTime edges[64];
};
 
inline PinToggleState& pinToggleState() {
    return fl::SingletonShared<PinToggleState>::instance();
}
#endif
 
#if defined(FASTLED_AUTORESEARCH_LPC_WS2812)
struct Ws2812State {
    CRGB leds[100];
    uint8_t expected[300];
    uint8_t decoded[300];
    fl::EdgeTime probe[64];
    bool fastled_initialized;
 
    Ws2812State() : fastled_initialized(false) {}
};
 
inline Ws2812State& ws2812State() {
    return fl::SingletonShared<Ws2812State>::instance();
}
#endif
 
}  // namespace low_memory
}  // namespace autoresearch
 
namespace {
 
#if defined(FL_IS_ARM_LPC) && !defined(FASTLED_AUTORESEARCH_IEEE754_MODE) && \
    !defined(FASTLED_AUTORESEARCH_FAULT_TEST)
// Period-stat helpers for `pinToggleRx`. Mirrors the FlexIO RX benchmark
// logic in `examples/AutoResearch/AutoResearchRemote.cpp::flexioRxBenchmark`
// but inline so we don't pull in the AutoResearch ObjectFLED bus.
struct LowMemPinTogglePeriodStats {
    fl::u32 periods;
    fl::u32 mean_ns;
    fl::u32 sigma_ns;
    fl::u32 min_ns;
    fl::u32 max_ns;
};
 
inline LowMemPinTogglePeriodStats computeLowMemPeriodStats(
    const fl::EdgeTime* edges, fl::size edge_count) FL_NO_EXCEPT {
    LowMemPinTogglePeriodStats s{0, 0, 0, 0, 0};
    fl::u64 sum    = 0;
    fl::u64 sum_sq = 0;
    fl::u32 min_ns = 0xFFFFFFFFu;
    fl::u32 max_ns = 0;
    fl::u32 count  = 0;
    for (fl::size i = 0; i + 1 < edge_count; i += 2) {
        const fl::u32 period_ns =
            static_cast<fl::u32>(edges[i].ns) +
            static_cast<fl::u32>(edges[i + 1].ns);
        if (period_ns == 0) continue;
        sum    += period_ns;
        sum_sq += static_cast<fl::u64>(period_ns) * static_cast<fl::u64>(period_ns);
        if (period_ns < min_ns) min_ns = period_ns;
        if (period_ns > max_ns) max_ns = period_ns;
        ++count;
    }
    if (count == 0) return s;
    const fl::u32 mean = static_cast<fl::u32>(sum / static_cast<fl::u64>(count));
    const fl::u64 mean64 = static_cast<fl::u64>(mean);
    const fl::u64 var = (sum_sq / static_cast<fl::u64>(count)) - (mean64 * mean64);
    fl::u32 sig = 0;
    while (static_cast<fl::u64>(sig + 1) * static_cast<fl::u64>(sig + 1) <= var) ++sig;
    s.periods  = count;
    s.mean_ns  = mean;
    s.sigma_ns = sig;
    s.min_ns   = (min_ns == 0xFFFFFFFFu) ? 0u : min_ns;
    s.max_ns   = max_ns;
    return s;
}
#endif  // FL_IS_ARM_LPC && !FASTLED_AUTORESEARCH_IEEE754_MODE && !FAULT_TEST
 
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_AUTORESEARCH_FAULT_TEST)
FL_NO_RETURN FL_NO_INLINE void triggerLowMemoryNullFault() FL_NO_EXCEPT {
    volatile fl::u32* const p =
        reinterpret_cast<volatile fl::u32*>(0u);  // ok reinterpret cast - fault test
    *p = 0x3302u;
    while (true) {}
}
 
FL_DISABLE_WARNING_PUSH
FL_DISABLE_WARNING(infinite-recursion)
FL_NO_INLINE int recurseLowMemoryStackBlow(int depth) FL_NO_EXCEPT {
    volatile fl::u8 pad[64] = {0};
    pad[static_cast<fl::u8>(depth) & 0x3Fu] = static_cast<fl::u8>(depth);
    // LPC845/M0+ has no stack-limit trap; unbounded recursion can corrupt the
    // runtime before the HardFault handler can emit. Burn stack frames, then
    // force the HardFault path while the diagnostic surface is still intact.
    if (depth >= 32) {
        triggerLowMemoryNullFault();
    }
    return recurseLowMemoryStackBlow(depth + 1) + pad[depth & 0x3F];
}
FL_DISABLE_WARNING_POP
#endif  // FL_IS_ARM_LPC_845 && FASTLED_AUTORESEARCH_FAULT_TEST
 
}  // namespace
 
inline void autoResearchLowMemorySetup() {
    fl::serial_begin(115200);
 
    // Arm the watchdog so a hung sketch unbricks itself on crash.
    fl::Watchdog::instance().begin(3000);
 
    // Emit a literal-only warning so the autoresearch harness can verify
    // the FL_WARN log pipeline reaches the host.
    FL_WARN_LIT("FL_WARN: low-memory bring-up OK");
 
    // The C++ inline-ODR rule guarantees a single shared instance across
    // every translation unit that calls this inline function, which is
    // exactly what we want (one Remote bound to the singleton Serial
    // transport). The included-once-per-sketch model of `.ino` builds
    // also reduces to a single TU in practice.
    fl::Remote& remote = autoresearch::low_memory::remoteState().remote;
    remote.bind("echo", [](int v) -> int {
        FL_WARN_LIT("FL_WARN: echo invoked");
        return v;
    });
 
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_AUTORESEARCH_FAULT_TEST)
    remote.bind("trigger_oom", []() -> bool {
        // Intentional #3302 fault input: ask the 16 KB SRAM target for
        // far more RAM than exists. If the platform allocator returns null
        // instead of trapping, dereference null to exercise HardFault emit.
        volatile char* const p = new char[16UL * 1024UL * 1024UL];  // ok bare allocation
        if (p == nullptr) {
            triggerLowMemoryNullFault();
        }
        p[0] = 0x33;
        triggerLowMemoryNullFault();
        return false;
    });
    remote.bind("trigger_stackblow", []() -> bool {
        (void)recurseLowMemoryStackBlow(0);
        triggerLowMemoryNullFault();
        return false;
    });
#endif  // FL_IS_ARM_LPC_845 && FASTLED_AUTORESEARCH_FAULT_TEST
 
#if defined(FL_IS_ESP8266)  // ok platform specific - ESP8266 bring-up benches
    autoresearch::esp8266::bindEsp8266Benches(remote);
#endif
 
#if defined(FASTLED_AUTORESEARCH_IEEE754_MODE)
    remote.bind("ieee754CodecTest", [](const fl::json& args) -> fl::json {
        (void)args;
        const auto r = autoresearch::ieee754_check::run();
        fl::json response = fl::json::object();
        response.set("success", r.success);
        response.set("tests_run", static_cast<int64_t>(r.tests_run));
        response.set("tests_failed", static_cast<int64_t>(r.tests_failed));
        response.set("first_failure", r.first_failure ? r.first_failure : "");
        response.set("expected_bits", static_cast<int64_t>(r.expected_bits));
        response.set("actual_bits", static_cast<int64_t>(r.actual_bits));
        return response;
    });
#endif
 
#if defined(FL_IS_ARM_LPC) && !defined(FASTLED_AUTORESEARCH_IEEE754_MODE) && \
    !defined(FASTLED_AUTORESEARCH_FAULT_TEST)
    // pinToggleRx (FastLED #3021 Phase 1) — bit-bang square wave on tx_pin
    // and capture SCT edges on rx_pin. CSV stats out.
#if !defined(FASTLED_AUTORESEARCH_LPC_DMA_LOOPBACK)
    // Left out of the RX-DMA loopback builds (--ws2812-loopback/--pwm-dma-cl):
    // with the DMA capture linked, the 64 KB LPC845 has no room for this
    // unrelated ~1 KB diagnostic. --pin-toggle-rx builds keep it.
    remote.bind("pinToggleRx",
        [](int tx_pin, int rx_pin, int freq_hz, int duration_ms) -> fl::string {
            if (tx_pin < 0 || rx_pin < 0 || freq_hz <= 0 || duration_ms <= 0) {
                return fl::string("0,0,0,0,0,0,0");
            }
            const fl::u32 expected_edges =
                2u * static_cast<fl::u32>(freq_hz) *
                     static_cast<fl::u32>(duration_ms) / 1000u;
            // Keep both the RX vector and diagnostic copy buffer small on
            // 16 KB SRAM LPC8xx parts. Larger static buffers regressed early
            // init by leaving too little room for stack/heap (FastLED #3200),
            // while stack buffers previously overflowed during this handler
            // (FastLED #3125).
            constexpr fl::u32 kLowMemEdgeBufSize = 64u;
            fl::u32 cap = expected_edges + (expected_edges / 2u);
            if (cap < 2u) cap = 2u;
            if (cap > kLowMemEdgeBufSize) cap = kLowMemEdgeBufSize;
 
            auto rx = fl::LpcSctRxChannel::create(rx_pin);
            if (!rx) return fl::string("0,0,0,0,0,0,0");
 
            fl::RxConfig cfg;
            cfg.buffer_size = cap;
            cfg.start_low   = true;
            if (!rx->begin(cfg)) return fl::string("0,0,0,0,0,0,0");
 
            pinMode(tx_pin, OUTPUT);
            digitalWrite(tx_pin, LOW);
 
            const fl::u32 half_us = 500000u / static_cast<fl::u32>(freq_hz);
            const fl::u32 cycles  = static_cast<fl::u32>(freq_hz) *
                                     static_cast<fl::u32>(duration_ms) / 1000u;
 
            for (fl::u32 i = 0; i < cycles; ++i) {
                digitalWrite(tx_pin, HIGH);
                delayMicroseconds(half_us);
                rx->pollOnce();
                digitalWrite(tx_pin, LOW);
                delayMicroseconds(half_us);
                rx->pollOnce();
                if ((i & 0x7Fu) == 0u) {
                    fl::Watchdog::instance().feed();
                }
            }
            rx->wait(1);
 
            // Static storage keeps this off the stack; the small fixed size
            // keeps .bss below the LPC845-BRK early-init failure threshold.
            fl::EdgeTime* edges_buf = autoresearch::low_memory::pinToggleState().edges;
            const fl::size n_read = rx->getRawEdgeTimes(
                fl::span<fl::EdgeTime>(edges_buf, sizeof(edges_buf) / sizeof(edges_buf[0])));
 
            LowMemPinTogglePeriodStats stats = computeLowMemPeriodStats(edges_buf, n_read);
 
            fl::sstream s;
            const bool success = (stats.periods > 0);
            s << (success ? 1 : 0) << ',' << static_cast<fl::u32>(n_read) << ','
              << stats.periods << ',' << stats.mean_ns << ',' << stats.sigma_ns << ','
              << stats.min_ns << ',' << stats.max_ns;
            return s.str();
        });
#endif  // !FASTLED_AUTORESEARCH_LPC_DMA_LOOPBACK
 
#if defined(FASTLED_AUTORESEARCH_LPC_WS2812)
    // ws2812SctTest (FastLED #3021 Phase 2) -- WS2812 byte-match loopback.
    remote.bind("ws2812SctTest",
        [](int test_case, int tx_pin, int rx_pin, int capture_ms) -> fl::string {
            if (test_case < 0 || test_case > 4 ||
                tx_pin < 0 || rx_pin < 0 || capture_ms <= 0) {
                return fl::string("0,0,0,0,0,0,0,0");
            }
            int num_leds = 1;
            switch (test_case) {
                case 1: num_leds = 3; break;
                case 4: num_leds = 100; break;
                default: num_leds = 1; break;
            }
            autoresearch::low_memory::Ws2812State& ws_state =
                autoresearch::low_memory::ws2812State();
            CRGB* leds_buf = ws_state.leds;
            for (int i = 0; i < num_leds; ++i) {
                switch (test_case) {
                    case 0: leds_buf[i] = CRGB(0xFF, 0x00, 0x00); break;
                    case 1: {
                        if (i == 0)      leds_buf[i] = CRGB(0xFF, 0x00, 0x00);
                        else if (i == 1) leds_buf[i] = CRGB(0x00, 0xFF, 0x00);
                        else             leds_buf[i] = CRGB(0x00, 0x00, 0xFF);
                        break;
                    }
                    case 2: leds_buf[i] = CRGB(0x00, 0x00, 0x00); break;
                    case 3: leds_buf[i] = CRGB(0xFF, 0xFF, 0xFF); break;
                    case 4: {
                        const uint8_t r = (i % 3 == 0) ? 0xFFu : 0u;
                        const uint8_t g = (i % 3 == 1) ? 0xFFu : 0u;
                        const uint8_t b = (i % 3 == 2) ? 0xFFu : 0u;
                        leds_buf[i] = CRGB(r, g, b);
                        break;
                    }
                }
            }
            const int expected_bytes = num_leds * 3;
            uint8_t* expected_buf = ws_state.expected;
            for (int i = 0; i < num_leds; ++i) {
                expected_buf[i * 3 + 0] = leds_buf[i].g;
                expected_buf[i * 3 + 1] = leds_buf[i].r;
                expected_buf[i * 3 + 2] = leds_buf[i].b;
            }
            auto rx = fl::LpcSctRxChannel::create(rx_pin);
            if (!rx) return fl::string("0,0,0,0,0,0,0,0");
            fl::RxConfig cfg;
            const fl::u32 expected_edges = (fl::u32)num_leds * 24u * 2u;
            fl::u32 cap = expected_edges + (expected_edges / 2u);
            // The low-memory sketch cannot afford the old 2048-edge reserve
            // on a 16 KB SRAM LPC845. 192 edges covers the 1- and 3-LED
            // sanity cases and fails the larger diagnostic cases without
            // starving setup()/loop() stack.
            constexpr fl::u32 kLowMemWs2812EdgeCapacity = 192u;
            if (cap < 48u) cap = 48u;
            if (cap > kLowMemWs2812EdgeCapacity) cap = kLowMemWs2812EdgeCapacity;
            cfg.buffer_size = cap;
            cfg.start_low   = true;
            if (!rx->begin(cfg)) return fl::string("0,0,0,0,0,0,0,0");
 
            constexpr int kFixedTxPin = 10;  // P0_10
            if (tx_pin != kFixedTxPin) {
                return fl::string("0,0,0,0,0,0,0,0");
            }
            if (!ws_state.fastled_initialized) {
                FastLED.addLeds<WS2812, kFixedTxPin, GRB>(leds_buf, 100);
                ws_state.fastled_initialized = true;
            }
            FastLED.show();
            rx->wait(capture_ms);
 
            uint8_t* decoded_buf = ws_state.decoded;
            for (int i = 0; i < expected_bytes; ++i) decoded_buf[i] = 0;
 
            fl::ChipsetTiming4Phase timing =
                fl::make4PhaseTiming(
                    fl::to_runtime_timing<fl::WS2812ChipsetTiming>(),
                    /*reset_us=*/0u);
 
            auto dec = rx->decode(timing, fl::span<u8>(decoded_buf, expected_bytes));
            const fl::u32 decoded_bytes = dec.ok() ? dec.value() : 0u;
 
            fl::u32 matched    = 0;
            fl::u32 mismatched = 0;
            for (fl::u32 i = 0; i < decoded_bytes && i < (fl::u32)expected_bytes; ++i) {
                if (decoded_buf[i] == expected_buf[i]) ++matched;
                else                                    ++mismatched;
            }
            const fl::u32 missing = (fl::u32)expected_bytes - decoded_bytes;
            mismatched += missing;
 
            // Diagnostic-only raw-edge sample. Keep this small in .bss; the
            // decoder uses the RX channel's bounded capture vector above.
            constexpr fl::size kLowMemWs2812ProbeSize = 64u;
            fl::EdgeTime* probe = ws_state.probe;
            const fl::size edges_captured = rx->getRawEdgeTimes(
                fl::span<fl::EdgeTime>(probe, kLowMemWs2812ProbeSize));
 
            const bool success = (mismatched == 0 && decoded_bytes == (fl::u32)expected_bytes);
 
            fl::sstream s;
            s << (success ? 1 : 0) << ',' << test_case << ',' << num_leds << ','
              << expected_bytes << ',' << decoded_bytes << ','
              << matched << ',' << mismatched << ','
              << static_cast<fl::u32>(edges_captured);
            return s.str();
        });
#endif  // FASTLED_AUTORESEARCH_LPC_WS2812
 
    // FastLED #3468: channels-API SCT+DMA clockless AutoResearch
    // harness. Binds pwmDmaClFrameOnce / pwmDmaClFrameBurst /
    // pwmDmaClCaptureSelf. Header self-gates on
    // FL_IS_ARM_LPC_845 && FASTLED_LPC_PWM_DMA.
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_LPC_PWM_DMA)
    autoresearch::pwm_dma_cl::bind(remote);
#endif
 
    // FastLED #3456: SPI+DMA async AutoResearch harness. Binds
    // dmaSpiTransferOnce / dmaSpiTransferOverlap / dmaSpiMeasureSck.
    // Header self-gates on FL_IS_ARM_LPC_845 && FASTLED_LPC_SPI_DMA.
#if defined(FL_IS_ARM_LPC_845) && defined(FASTLED_LPC_SPI_DMA)
    autoresearch::dma_spi::bind(remote);
#endif
 
    // #3453/#3611: UART DMA AutoResearch harness. Binds either the raw
    // UART DMA stream bench or the clockless loopback verifier, depending
    // on the build flags injected by `bash autoresearch`.
#if defined(FL_IS_ARM_LPC_845) && FASTLED_AUTORESEARCH_LPC_UART_DMA
    autoresearch::uart_dma::bind(remote);
#endif
 
#endif  // FL_IS_ARM_LPC && !FASTLED_AUTORESEARCH_IEEE754_MODE
}
 
inline void autoResearchLowMemoryLoop() {
    fl::Watchdog::instance().feed();
    autoresearch::low_memory::remoteState().remote.update(millis());
}