KeylogConfig.h

/**
 * @file  KeylogConfig.h
 * @brief Global configuration, data structures, and utility functions.
 *
 * Defines hardware pins, flash memory layout, packed event format,
 * inter-core communication primitives, CRC lookup tables, and
 * security utilities (secure_memzero, timing_safe_equal).
 */

#pragma once
#include <Arduino.h>
#include <hardware/sync.h>

// =============================================================================
// HARDWARE — Pin Assignments
// =============================================================================

#define PIN_SNIFFER_DP 16
#define PIN_NEOPIXEL   25

// =============================================================================
// FLASH MEMORY — Layout Overview
// =============================================================================

#define FLASH_LOG_SIZE     (1024 * 1024)
#define FLASH_LOG_START    (PICO_FLASH_SIZE_BYTES - FLASH_LOG_SIZE)

#ifndef FLASH_SECTOR_SIZE
    #define FLASH_SECTOR_SIZE 4096
#endif
#ifndef FLASH_PAGE_SIZE
    #define FLASH_PAGE_SIZE 256
#endif

// =============================================================================
// METADATA SECTOR — Crash-Safe State Journal
// =============================================================================

#define FLASH_META_START (FLASH_LOG_START - FLASH_SECTOR_SIZE)
#define META_MAGIC       0x4B4C4F47
#define META_ENTRIES_MAX (FLASH_SECTOR_SIZE / FLASH_PAGE_SIZE)  // 16

/**
 * @struct FlashMeta
 * @brief  Crash-safe state persisted periodically to flash.
 *
 * @details v2.3.1: nonce_floor moved here from CryptoHeader (E2/S4).
 *          This eliminates the erase+program of the crypto sector on
 *          every metadata persist, extending crypto sector life ~100×.
 *          CRC covers bytes [0..23].
 */
struct FlashMeta {
    uint32_t magic;          ///< Must be META_MAGIC for valid entry
    uint32_t write_offset;   ///< Current byte offset into the log region
    uint32_t events_logged;  ///< Events currently in the log (accurate after wrap)
    uint32_t nonce_counter;  ///< Monotonic CTR nonce (never wraps with same DEK)
    uint32_t boot_uptime_ms; ///< millis() at time of persist (timeline anchor)
    uint32_t nonce_floor;    ///< Minimum accepted nonce on boot (replay protection)
    uint16_t crc16;          ///< CRC-16/CCITT of bytes [0..23]
    uint16_t _reserved;      ///< Padding to 28 bytes (set to 0)
};

/** @brief Number of bytes covered by the FlashMeta CRC (up to nonce_floor). */
#define META_CRC_SPAN 24

// =============================================================================
// CRYPTO SECTOR
// =============================================================================

#define FLASH_CRYPTO_START (FLASH_META_START - FLASH_SECTOR_SIZE)

// =============================================================================
// DATA PAGE LAYOUT — CRC-Protected Pages (256 bytes)
// =============================================================================

#define EVENTS_PER_PAGE    62
#define PAGE_COUNT_OFFSET  (EVENTS_PER_PAGE * 4)   // 248
#define PAGE_FLAGS_OFFSET  (PAGE_COUNT_OFFSET + 1)  // 249
#define PAGE_NONCE_OFFSET  (PAGE_FLAGS_OFFSET + 1)  // 250
#define PAGE_CRC_OFFSET    (PAGE_NONCE_OFFSET + 4)  // 254

// =============================================================================
// PACKED EVENT STRUCTURE — 4 Bytes per Keystroke
// =============================================================================

struct PackedEvent {
    uint8_t  scancode;
    uint8_t  meta;
    uint16_t delta_ms;
};

// =============================================================================
// INTER-CORE RING BUFFER
// =============================================================================

#define RAM_BUFFER_SIZE 512

extern volatile PackedEvent ram_buffer[RAM_BUFFER_SIZE];
extern volatile uint16_t head_idx;
extern volatile uint16_t tail_idx;

// =============================================================================
// RING BUFFER OVERFLOW COUNTER
// =============================================================================

extern volatile uint32_t overflow_count;

// =============================================================================
// USB PACKET COUNTERS
// =============================================================================

extern volatile uint32_t usb_packets_total;
extern volatile uint32_t usb_packets_hid;

// =============================================================================
// INTER-CORE SYNCHRONIZATION FLAGS
// =============================================================================

extern volatile bool core0_request_pause;
extern volatile bool core1_ack_pause;
extern volatile bool core1_running;

// =============================================================================
// CORE 1 HEARTBEAT
// =============================================================================

extern volatile uint32_t core1_heartbeat_us;
#define CORE1_HEARTBEAT_TIMEOUT_US 2000000

// =============================================================================
// SERIAL COMMAND FLAGS
// =============================================================================

extern volatile bool dump_request;
extern volatile bool dump_hex_request;
extern volatile bool delete_request;
extern volatile bool cancel_request;

// =============================================================================
// INTER-CORE PAUSE HANDSHAKE TIMEOUT
// =============================================================================

#define PAUSE_HANDSHAKE_TIMEOUT_US 100000

// =============================================================================
// MULTI-KEYBOARD SUPPORT
// =============================================================================

#define MAX_TRACKED_KEYBOARDS 4

// =============================================================================
// SESSION MARKER
// =============================================================================

#define SCANCODE_SESSION_MARKER 0xFE

// =============================================================================
// PARTIAL PAGE FLUSH INTERVAL
// =============================================================================

#define FLUSH_INTERVAL_MS  60000
#define FLUSH_MIN_EVENTS   16

// =============================================================================
// METADATA PERSIST INTERVAL
// =============================================================================

#define META_PERSIST_INTERVAL 16

// =============================================================================
// PASSWORD LENGTH LIMIT
// =============================================================================

#define PASSWORD_MAX_LEN 64

// =============================================================================
// COMMAND BUFFER SIZE
// =============================================================================

#define CMD_BUFFER_SIZE 144

// =============================================================================
// READ PIN BRUTE-FORCE PROTECTION
// =============================================================================

#define RPIN_MAX_FAST_ATTEMPTS  3
#define RPIN_LOCKOUT_BASE_MS    1000
#define RPIN_LOCKOUT_MAX_MS     15000

// =============================================================================
// FIRMWARE INTEGRITY
// =============================================================================

#define FW_CRC_SIZE 16384

// =============================================================================
// LIVE MODE (U4 — clean mode suppresses modifier tags)
// =============================================================================

extern volatile bool live_mode_active;

/** @brief When true, LIVE suppresses [LSFT]/[/LSFT] style modifier tags. */
extern volatile bool live_clean_mode;

// =============================================================================
// USER EPOCH TIMESTAMP (U3 — absolute times in EXPORT)
// =============================================================================

/**
 * @brief Unix epoch seconds set by the TIME command. 0 = unset.
 * @details Current time = user_epoch_seconds + (millis() - epoch_set_millis) / 1000.
 */
extern uint32_t user_epoch_seconds;

/** @brief millis() at the moment TIME was issued. */
extern uint32_t epoch_set_millis;

// =============================================================================
// FLASH WEAR COUNTERS (E3 — displayed in STAT)
// =============================================================================

/** @brief Metadata sector erases since boot. */
extern uint32_t flash_wear_meta_erases;

/** @brief Log sector erases since boot. */
extern uint32_t flash_wear_log_erases;

// =============================================================================
// SERIAL FLOW CONTROL TIMEOUT (R2/R5)
// =============================================================================

/** @brief Maximum time serialFlowWait() will block before returning false. */
#define SERIAL_FLOW_TIMEOUT_MS 5000

// =============================================================================
// MEMORY BARRIER HELPER
// =============================================================================

static inline void memory_barrier() {
    __dmb();
}

// =============================================================================
// CRC-16/CCITT — Lookup Table (~8× faster)
// =============================================================================

static const uint16_t __in_flash("crc16") crc16_table[256] = {
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
    0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
    0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
    0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
    0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
    0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
    0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
    0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
    0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
    0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
    0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
    0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
    0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
    0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
    0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
    0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
    0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
    0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
    0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
    0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
    0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
    0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
    0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
    0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
    0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
    0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
    0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
    0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
    0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};

static inline uint16_t calcCRC16(const uint8_t* data, uint16_t length) {
    uint16_t crc = 0xFFFF;
    for (uint16_t i = 0; i < length; i++) {
        crc = (crc << 8) ^ crc16_table[((crc >> 8) ^ data[i]) & 0xFF];
    }
    return crc;
}

// =============================================================================
// CRC-32 — Lookup Table (~8× faster)
// =============================================================================

static const uint32_t __in_flash("crc32") crc32_table[256] = {
    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
    0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
    0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
    0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
    0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
    0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
    0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
    0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
    0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
    0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
    0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
    0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
    0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
    0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
    0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
    0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
    0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
    0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
    0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
    0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
    0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
    0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
    0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
    0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
    0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
    0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
    0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
    0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
    0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
    0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
    0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
    0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
    0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
    0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
    0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
    0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
    0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
    0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
    0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
    0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
    0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

static inline uint32_t calcCRC32(const uint8_t* data, uint32_t length) {
    uint32_t crc = 0xFFFFFFFF;
    for (uint32_t i = 0; i < length; i++) {
        crc = (crc >> 8) ^ crc32_table[(crc ^ data[i]) & 0xFF];
    }
    return ~crc;
}

// =============================================================================
// SECURE MEMORY SCRUB
// =============================================================================

static inline void secure_memzero(void* ptr, size_t len) {
    volatile uint8_t* vp = (volatile uint8_t*)ptr;
    while (len--) { *vp++ = 0; }
}

// =============================================================================
// TIMING-SAFE COMPARISON
// =============================================================================

static inline bool timing_safe_equal(const void* a, const void* b, size_t len) {
    const volatile uint8_t* va = (const volatile uint8_t*)a;
    const volatile uint8_t* vb = (const volatile uint8_t*)b;
    volatile uint8_t diff = 0;
    for (size_t i = 0; i < len; i++) { diff |= va[i] ^ vb[i]; }
    return diff == 0;
}