#ifndef PROTOCOL_H
#define PROTOCOL_H

#include <stddef.h>
#include <stdint.h>

// Protocol Constants
#define PROTOCOL_SOF 0xAA
#define PACKET_TYPE_AUDIO 0x02
#define PACKET_LEN_V1 0x08  // Payload length (excluding SOF, TYPE, LEN, CRC)
#define PACKET_TOTAL_SIZE 12

// CRC8-ATM Constants
#define CRC8_POLY 0x07
#define CRC8_INIT 0x00

/**
 * @brief  Calculates CRC-8/ATM over the data buffer.
 *         Polynomial: x^8 + x^2 + x + 1 (0x07)
 *         Init: 0x00, RefIn: false, RefOut: false, XorOut: 0x00
 * @param  data Pointer to data buffer
 * @param  len  Length of data
 * @return Calculated CRC8
 */
uint8_t crc8_atm(const uint8_t *data, size_t len);

/**
 * @brief Encodes the audio metric packet into the wire format.
 * @param buf Output buffer (must be at least 12 bytes)
 * @param timestamp_ms Timestamp in milliseconds
 * @param rms_dbfs RMS value in dBFS (float)
 * @param freq_hz Peak frequency in Hz (float)
 */
void protocol_pack_v1(
    uint8_t *buf,
    uint32_t timestamp_ms,
    float rms_dbfs,
    float freq_hz);

#endif  // PROTOCOL_H