/*
 * MIT License
 *
 * Copyright (c) 2023 Gabor L Ugray
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef CHIRPY_TX_H
#define CHIRPY_TX_H

/** @brief Calculates the CRC of a byte sequence.
 */
uint8_t chirpy_crc8(const uint8_t *addr, uint16_t len);

/** @brief Updates a CRC value with the next byte of input.
 */
uint8_t chirpy_update_crc8(uint8_t next_byte, uint8_t crc);

/** @brief Function to return next byte to be encoded.
 * @param next_byte Pointer where implementor must write next byte (if available).
 * @return 1 if there is a next byte, or 0 if no more data to encode.
 */
typedef uint8_t (*chirpy_get_next_byte_t)(uint8_t *next_byte);

#define CHIRPY_TONE_BUF_SIZE 16

// Holds state used by the encoder. Do not manipulate directly.
typedef struct {
    uint8_t tone_buf[CHIRPY_TONE_BUF_SIZE];
    uint8_t tone_pos;
    uint8_t tone_count;
    uint8_t block_len;
    uint8_t block_size;
    uint8_t crc;
    uint16_t bits;
    uint8_t bit_count;
    chirpy_get_next_byte_t get_next_byte;
} chirpy_encoder_state_t;

/** @brief Iniitializes the encoder state to be used during the transmission.
 * @param ces Pointer to encoder state object to be initialized.
 * @param get_next_byte Pointer to function that the encoder will call to fetch data byte by byte.
 */
void chirpy_init_encoder(chirpy_encoder_state_t *ces, chirpy_get_next_byte_t get_next_byte);

/** @brief Returns the next tone to be transmitted.
 * @details This function will call the get_next_byte function stored in the encoder state to
 *          retrieve the next byte to be transmitted as needed. As a single byte is encoded as several tones,
 *          and because the transmission also includes periodic CRC values, not every call to this function
 *          will result in a callback for the next data byte.
 * @param ced Pointer to the encoder state object.
 * @return A tone index from 0 to N (where N is the largest tone index), or 255 if the transmission is over.
 */
uint8_t chirpy_get_next_tone(chirpy_encoder_state_t *ces);

/** @brief Returns the period value for buzzing out a tone.
 * @param tone The tone index, 0 thru 8.
 * @return The period for the tone's frequency, i.e., 1_000_000 / freq.
 */
uint16_t chirpy_get_tone_period(uint8_t tone);

/** @brief Typedef for a tick handler function.
 */
typedef void (*chirpy_tick_fun_t)(void *context);

/** @brief Creature-comfort struct for use in your chirping code.
 * @details The idea is to handle a tick that happens 64 times per second at the outermost level.
 *          To get to the desired ~20 tones per second, increment a counter and call the actual
 *          transmission ticker when tick_counter reaches tick_compare, with a compare value of 3.
 *          seq_pos is for use by the transmission function to keep track of where it is in the data.
 *          The current transmission function is stored in tick_fun. You can have multiple phases
 *          by switching to a different function. E.g., intro countdown first, followed by data chirping.
 */
typedef struct {
    uint8_t tick_count;
    uint8_t tick_compare;
    uint16_t seq_pos;
    chirpy_tick_fun_t tick_fun;
} chirpy_tick_state_t;

#endif