Config.h

#pragma once
#include <Arduino.h>

// ---------------------------------------------------------------------------
// MiniLoopDeck - global configuration
// ---------------------------------------------------------------------------
// Lo-Fi sample looper for the M5Stack Core2.
//
// Important hardware constraint: on the Core2 the microphone (SPM1423 PDM)
// and the speaker amp share the same I2S peripheral, so they can NOT run at
// the same time. The deck therefore works in two phases:
//   1) record ONE track (speaker off)
//   2) loop ALL tracks mixed together (mic off)
// True live-overdub while the speaker plays is not possible on this board.
// ---------------------------------------------------------------------------

// Audio format -------------------------------------------------------------
static constexpr uint32_t SAMPLE_RATE   = 16000;   // 16 kHz, lo-fi but plenty
static constexpr uint8_t  NUM_TRACKS    = 4;       // 2-4 recommended
static constexpr uint32_t MAX_SECONDS   = 10;      // max loop length per track
static constexpr uint32_t MAX_SAMPLES   = SAMPLE_RATE * MAX_SECONDS; // per track

// Engine internals ---------------------------------------------------------
static constexpr size_t   REC_CHUNK          = 1024; // samples queued per service
static constexpr uint8_t  MASTER_VOLUME      = 200;  // 0..255
// Mic/PDM + DC filter need to settle after begin(); discard this many samples
// before recording, otherwise every take starts with an audible click/pop.
static constexpr uint32_t MIC_WARMUP_SAMPLES = SAMPLE_RATE / 8; // ~125 ms

// Loop matching ------------------------------------------------------------
// Onset trim: drop leading silence so the loop starts on the first hit.
static constexpr int32_t  ONSET_FLOOR     = 200;               // min threshold
static constexpr uint32_t ONSET_PREROLL   = SAMPLE_RATE * 5 / 1000;  // keep 5 ms attack
// Seam smoothing: tiny linear fade at both ends to kill the loop-point click.
static constexpr uint32_t FADE_SAMPLES    = SAMPLE_RATE * 3 / 1000;  // ~3 ms
// Remote (StickS3) takes: drop the tail so the KEY1-release transient that the
// mic picks up at the end of a take is removed before looping.
static constexpr uint32_t REMOTE_TAIL_TRIM = SAMPLE_RATE * 90 / 1000; // ~90 ms
// Auto-align: nudge a follower loop to best-match the master groove.
static constexpr uint32_t ALIGN_WINDOW    = SAMPLE_RATE * 60 / 1000; // +/- 60 ms
static constexpr uint32_t ALIGN_DECIM     = 8;                 // correlation stride
static constexpr uint32_t ALIGN_CMP_LEN   = SAMPLE_RATE;       // compare 1 s max
// Visual metronome subdivides the master loop into this many beats.
static constexpr uint8_t  BEATS_PER_LOOP  = 4;
static constexpr uint32_t BEAT_FLASH_MS   = 90;

// Effects ------------------------------------------------------------------
enum Fx : uint8_t {
  FX_NONE = 0,
  FX_REVERSE,
  FX_BITCRUSH,
  FX_LOFI,
  FX_DRIVE,
  FX_ECHO,
  FX_COUNT
};

static const char* const FX_NAMES[FX_COUNT] = {
  "DRY", "REVERSE", "CRUSH", "LOFI", "DRIVE", "ECHO"
};

// Effect tuning
static constexpr uint32_t ECHO_DELAY  = SAMPLE_RATE / 4; // 0.25 s slap-back
static constexpr uint8_t  LOFI_DECIM  = 4;               // sample-and-hold factor
static constexpr int16_t  CRUSH_MASK  = (int16_t)0xF000; // keep top 4 bits
static constexpr int32_t  DRIVE_GAIN  = 4;               // pre-clip gain

// Deck state machine -------------------------------------------------------
enum DeckState : uint8_t {
  STATE_IDLE = 0,
  STATE_RECORDING,
  STATE_PLAYING
};

// Saturating 32 -> 16 bit conversion used all over the mixer.
static inline int16_t clip16(int32_t v) {
  if (v >  32767) return  32767;
  if (v < -32768) return -32768;
  return (int16_t)v;
}