// Copyright 2015-2021 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <inttypes.h>
#include <string.h>
#include <math.h>

#include "sdkconfig.h"
#include "esp_attr.h"
#include "rom/gpio.h"
#include "soc/gpio_sig_map.h"
#include "hal/gpio_types.h"
#include "driver/gpio.h"
#include "esp_err.h"

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "freertos/semphr.h"
#include "freertos/ringbuf.h"

#include "esp_intr_alloc.h"
#include "driver/periph_ctrl.h"
#include "soc/i2c_reg.h"
#include "soc/i2c_struct.h"
#include "hal/i2c_ll.h"
#include "esp32-hal-log.h"
#include "esp32-hal-i2c-slave.h"

#define I2C_SLAVE_USE_RX_QUEUE 0 // 1: Queue, 0: RingBuffer

#if SOC_I2C_NUM > 1
#define I2C_SCL_IDX(p)  ((p==0)?I2CEXT0_SCL_OUT_IDX:((p==1)?I2CEXT1_SCL_OUT_IDX:0))
#define I2C_SDA_IDX(p) ((p==0)?I2CEXT0_SDA_OUT_IDX:((p==1)?I2CEXT1_SDA_OUT_IDX:0))
#else
#define I2C_SCL_IDX(p)  I2CEXT0_SCL_OUT_IDX
#define I2C_SDA_IDX(p) I2CEXT0_SDA_OUT_IDX
#endif

#if CONFIG_IDF_TARGET_ESP32
    #define I2C_TXFIFO_WM_INT_ENA    I2C_TXFIFO_EMPTY_INT_ENA
    #define I2C_RXFIFO_WM_INT_ENA     I2C_RXFIFO_FULL_INT_ENA
#endif

enum {
    I2C_SLAVE_EVT_RX, I2C_SLAVE_EVT_TX
};

typedef struct i2c_slave_struct_t {
    i2c_dev_t * dev;
    uint8_t num;
    int8_t sda;
    int8_t scl;
    i2c_slave_request_cb_t request_callback;
    i2c_slave_receive_cb_t receive_callback;
    void * arg;
    intr_handle_t intr_handle;
    TaskHandle_t task_handle;
    xQueueHandle event_queue;
#if I2C_SLAVE_USE_RX_QUEUE
    xQueueHandle rx_queue;
#else
    RingbufHandle_t rx_ring_buf;
#endif
    xQueueHandle tx_queue;
    uint32_t rx_data_count;
#if !CONFIG_DISABLE_HAL_LOCKS
    xSemaphoreHandle lock;
#endif
} i2c_slave_struct_t;

typedef union {
    struct {
        uint32_t event : 2;
        uint32_t stop : 1;
        uint32_t param : 29;
    };
    uint32_t val;
} i2c_slave_queue_event_t;

static i2c_slave_struct_t _i2c_bus_array[SOC_I2C_NUM] = {
    { &I2C0, 0, -1, -1, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0
#if !CONFIG_DISABLE_HAL_LOCKS
    , NULL
#endif
    },
#if SOC_I2C_NUM > 1
    { &I2C1, 1, -1, -1, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0
#if !CONFIG_DISABLE_HAL_LOCKS
    , NULL
#endif
    }
#endif
};

#if CONFIG_DISABLE_HAL_LOCKS
#define I2C_SLAVE_MUTEX_LOCK()
#define I2C_SLAVE_MUTEX_UNLOCK()
#else
#define I2C_SLAVE_MUTEX_LOCK()    if(i2c->lock){xSemaphoreTake(i2c->lock, portMAX_DELAY);}
#define I2C_SLAVE_MUTEX_UNLOCK()  if(i2c->lock){xSemaphoreGive(i2c->lock);}
#endif

//-------------------------------------- HAL_LL (Missing Functions) ------------------------------------------------
typedef enum {
    I2C_STRETCH_CAUSE_MASTER_READ,
    I2C_STRETCH_CAUSE_TX_FIFO_EMPTY,
    I2C_STRETCH_CAUSE_RX_FIFO_FULL,
    I2C_STRETCH_CAUSE_MAX
} i2c_stretch_cause_t;

static inline i2c_stretch_cause_t i2c_ll_stretch_cause(i2c_dev_t *hw)
{
#if CONFIG_IDF_TARGET_ESP32C3 || CONFIG_IDF_TARGET_ESP32S3
    return hw->sr.stretch_cause;
#elif CONFIG_IDF_TARGET_ESP32S2
    return hw->status_reg.stretch_cause;
#else
    return I2C_STRETCH_CAUSE_MAX;
#endif
}

static inline void i2c_ll_set_stretch(i2c_dev_t *hw, uint16_t time)
{
#ifndef CONFIG_IDF_TARGET_ESP32
    typeof(hw->scl_stretch_conf) scl_stretch_conf;
    scl_stretch_conf.val = 0;
    scl_stretch_conf.slave_scl_stretch_en = (time > 0);
    scl_stretch_conf.stretch_protect_num = time;
    scl_stretch_conf.slave_scl_stretch_clr = 1;
    hw->scl_stretch_conf.val = scl_stretch_conf.val;
    if(time > 0){
        //enable interrupt
        hw->int_ena.val |= I2C_SLAVE_STRETCH_INT_ENA;
    } else {
        //disable interrupt
        hw->int_ena.val &= (~I2C_SLAVE_STRETCH_INT_ENA);
    }
#endif
}

static inline void i2c_ll_stretch_clr(i2c_dev_t *hw)
{
#ifndef CONFIG_IDF_TARGET_ESP32
    hw->scl_stretch_conf.slave_scl_stretch_clr = 1;
#endif
}

static inline bool i2c_ll_slave_addressed(i2c_dev_t *hw)
{
#if CONFIG_IDF_TARGET_ESP32C3 || CONFIG_IDF_TARGET_ESP32S3
    return hw->sr.slave_addressed;
#else
    return hw->status_reg.slave_addressed;
#endif
}

static inline bool i2c_ll_slave_rw(i2c_dev_t *hw)//not exposed by hal_ll
{
#if CONFIG_IDF_TARGET_ESP32C3 || CONFIG_IDF_TARGET_ESP32S3
    return hw->sr.slave_rw;
#else
    return hw->status_reg.slave_rw;
#endif
}

//-------------------------------------- PRIVATE (Function Prototypes) ------------------------------------------------
static void i2c_slave_free_resources(i2c_slave_struct_t * i2c);
static void i2c_slave_delay_us(uint64_t us);
static void i2c_slave_gpio_mode(int8_t pin, gpio_mode_t mode);
static bool i2c_slave_check_line_state(int8_t sda, int8_t scl);
static bool i2c_slave_attach_gpio(i2c_slave_struct_t * i2c, int8_t sda, int8_t scl);
static bool i2c_slave_detach_gpio(i2c_slave_struct_t * i2c);
static bool i2c_slave_set_frequency(i2c_slave_struct_t * i2c, uint32_t clk_speed);
static bool i2c_slave_send_event(i2c_slave_struct_t * i2c, i2c_slave_queue_event_t* event);
static bool i2c_slave_handle_tx_fifo_empty(i2c_slave_struct_t * i2c);
static bool i2c_slave_handle_rx_fifo_full(i2c_slave_struct_t * i2c, uint32_t len);
static size_t i2c_slave_read_rx(i2c_slave_struct_t * i2c, uint8_t * data, size_t len);
static void i2c_slave_isr_handler(void* arg);
static void i2c_slave_task(void *pv_args);


//=====================================================================================================================
//-------------------------------------- Public Functions -------------------------------------------------------------
//=====================================================================================================================

esp_err_t i2cSlaveAttachCallbacks(uint8_t num, i2c_slave_request_cb_t request_callback, i2c_slave_receive_cb_t receive_callback, void * arg){
    if(num >= SOC_I2C_NUM){
        log_e("Invalid port num: %u", num);
        return ESP_ERR_INVALID_ARG;
    }
    i2c_slave_struct_t * i2c = &_i2c_bus_array[num];
    I2C_SLAVE_MUTEX_LOCK();
    i2c->request_callback = request_callback;
    i2c->receive_callback = receive_callback;
    i2c->arg = arg;
    I2C_SLAVE_MUTEX_UNLOCK();
    return ESP_OK;
}

esp_err_t i2cSlaveInit(uint8_t num, int sda, int scl, uint16_t slaveID, uint32_t frequency, size_t rx_len, size_t tx_len) {
    if(num >= SOC_I2C_NUM){
        log_e("Invalid port num: %u", num);
        return ESP_ERR_INVALID_ARG;
    }

    if (sda < 0 || scl < 0) {
        log_e("invalid pins sda=%d, scl=%d", sda, scl);
        return ESP_ERR_INVALID_ARG;
    }

    if(!frequency){
        frequency = 100000;
    } else if(frequency > 1000000){
        frequency = 1000000;
    }

    log_i("Initialising I2C Slave: sda=%d scl=%d freq=%d, addr=0x%x", sda, scl, frequency, slaveID);

    i2c_slave_struct_t * i2c = &_i2c_bus_array[num];
    esp_err_t ret = ESP_OK;

#if !CONFIG_DISABLE_HAL_LOCKS
    if(!i2c->lock){
        i2c->lock = xSemaphoreCreateMutex();
        if (i2c->lock == NULL) {
            log_e("RX queue create failed");
            return ESP_ERR_NO_MEM;
        }
    }
#endif

    I2C_SLAVE_MUTEX_LOCK();
    i2c_slave_free_resources(i2c);

#if I2C_SLAVE_USE_RX_QUEUE
    i2c->rx_queue = xQueueCreate(rx_len, sizeof(uint8_t));
    if (i2c->rx_queue == NULL) {
        log_e("RX queue create failed");
        ret = ESP_ERR_NO_MEM;
        goto fail;
    }
#else
    i2c->rx_ring_buf = xRingbufferCreate(rx_len, RINGBUF_TYPE_BYTEBUF);
    if (i2c->rx_ring_buf == NULL) {
        log_e("RX RingBuf create failed");
        ret = ESP_ERR_NO_MEM;
        goto fail;
    }
#endif

    i2c->tx_queue = xQueueCreate(tx_len, sizeof(uint8_t));
    if (i2c->tx_queue == NULL) {
        log_e("TX queue create failed");
        ret = ESP_ERR_NO_MEM;
        goto fail;
    }

    i2c->event_queue = xQueueCreate(16, sizeof(i2c_slave_queue_event_t));
    if (i2c->event_queue == NULL) {
        log_e("Event queue create failed");
        ret = ESP_ERR_NO_MEM;
        goto fail;
    }

    xTaskCreate(i2c_slave_task, "i2c_slave_task", 4096, i2c, 20, &i2c->task_handle);
    if(i2c->task_handle == NULL){
        log_e("Event thread create failed");
        ret = ESP_ERR_NO_MEM;
        goto fail;
    }

    if (frequency == 0) {
        frequency = 100000L;
    }
    frequency = (frequency * 5) / 4;

    if (i2c->num == 0) {
        periph_module_enable(PERIPH_I2C0_MODULE);
#if SOC_I2C_NUM > 1
    } else {
        periph_module_enable(PERIPH_I2C1_MODULE);
#endif
    }
    
    i2c_ll_slave_init(i2c->dev);
    i2c_ll_set_fifo_mode(i2c->dev, true);
    i2c_ll_set_slave_addr(i2c->dev, slaveID, false);
    i2c_ll_set_tout(i2c->dev, I2C_LL_MAX_TIMEOUT);
    i2c_slave_set_frequency(i2c, frequency);

    if (!i2c_slave_check_line_state(sda, scl)) {
        log_e("bad pin state");
        ret = ESP_FAIL;
        goto fail;
    }

    i2c_slave_attach_gpio(i2c, sda, scl);

    if (i2c_ll_is_bus_busy(i2c->dev)) {
        log_w("Bus busy, reinit");
        ret = ESP_FAIL;
        goto fail;
    }

    i2c_ll_disable_intr_mask(i2c->dev, I2C_LL_INTR_MASK);
    i2c_ll_clr_intsts_mask(i2c->dev, I2C_LL_INTR_MASK);
    i2c_ll_set_fifo_mode(i2c->dev, true);

    if (!i2c->intr_handle) {
        uint32_t flags = ESP_INTR_FLAG_LOWMED | ESP_INTR_FLAG_SHARED;
        if(i2c->num == 0) {
            ret = esp_intr_alloc(ETS_I2C_EXT0_INTR_SOURCE, flags, &i2c_slave_isr_handler, i2c, &i2c->intr_handle);
#if SOC_I2C_NUM > 1
        } else {
            ret = esp_intr_alloc(ETS_I2C_EXT1_INTR_SOURCE, flags, &i2c_slave_isr_handler, i2c, &i2c->intr_handle);
#endif
        }

        if (ret != ESP_OK) {
            log_e("install interrupt handler Failed=%d", ret);
            goto fail;
        }
    }
    
    i2c_ll_txfifo_rst(i2c->dev);
    i2c_ll_rxfifo_rst(i2c->dev);
    i2c_ll_slave_enable_rx_it(i2c->dev);
    i2c_ll_set_stretch(i2c->dev, 0x3FF);
    i2c_ll_update(i2c->dev);
    I2C_SLAVE_MUTEX_UNLOCK();
    return ret;

fail:
    i2c_slave_free_resources(i2c);
    I2C_SLAVE_MUTEX_UNLOCK();
    return ret;
}

esp_err_t i2cSlaveDeinit(uint8_t num){
    if(num >= SOC_I2C_NUM){
        log_e("Invalid port num: %u", num);
        return ESP_ERR_INVALID_ARG;
    }

    i2c_slave_struct_t * i2c = &_i2c_bus_array[num];
#if !CONFIG_DISABLE_HAL_LOCKS
    if(!i2c->lock){
        log_e("Lock is not initialized! Did you call i2c_slave_init()?");
        return ESP_ERR_NO_MEM;
    }
#endif
    I2C_SLAVE_MUTEX_LOCK();
    i2c_slave_free_resources(i2c);
    I2C_SLAVE_MUTEX_UNLOCK();
    return ESP_OK;
}

size_t i2cSlaveWrite(uint8_t num, const uint8_t *buf, uint32_t len, uint32_t timeout_ms) {
    if(num >= SOC_I2C_NUM){
        log_e("Invalid port num: %u", num);
        return 0;
    }
    size_t to_queue = 0, to_fifo = 0;
    i2c_slave_struct_t * i2c = &_i2c_bus_array[num];
#if !CONFIG_DISABLE_HAL_LOCKS
    if(!i2c->lock){
        log_e("Lock is not initialized! Did you call i2c_slave_init()?");
        return ESP_ERR_NO_MEM;
    }
#endif
    if(!i2c->tx_queue){
        return 0;
    }
    I2C_SLAVE_MUTEX_LOCK();
#if CONFIG_IDF_TARGET_ESP32
    i2c_ll_slave_disable_tx_it(i2c->dev);
    if (i2c_ll_get_txfifo_len(i2c->dev) < SOC_I2C_FIFO_LEN) {
        i2c_ll_txfifo_rst(i2c->dev);
    }
#endif
    to_fifo = i2c_ll_get_txfifo_len(i2c->dev);
    if(len < to_fifo){
        to_fifo = len;
    }
    i2c_ll_write_txfifo(i2c->dev, (uint8_t*)buf, to_fifo);
    buf += to_fifo;
    len -= to_fifo;
    //reset tx_queue
    xQueueReset(i2c->tx_queue);
    //write the rest of the bytes to the queue
    if(len){
        to_queue = uxQueueSpacesAvailable(i2c->tx_queue);
        if(len < to_queue){
            to_queue = len;
        }
        for (size_t i = 0; i < to_queue; i++) {
            if (xQueueSend(i2c->tx_queue, &buf[i], timeout_ms / portTICK_RATE_MS) != pdTRUE) {
                xQueueReset(i2c->tx_queue);
                to_queue = 0;
                break;
            }
        }
        //no need to enable TX_EMPTY if tx_queue is empty
        if(to_queue){
            i2c_ll_slave_enable_tx_it(i2c->dev);
        }
    }
    I2C_SLAVE_MUTEX_UNLOCK();
    return to_queue + to_fifo;
}

//=====================================================================================================================
//-------------------------------------- Private Functions ------------------------------------------------------------
//=====================================================================================================================

static void i2c_slave_free_resources(i2c_slave_struct_t * i2c){
    i2c_slave_detach_gpio(i2c);
    i2c_ll_set_slave_addr(i2c->dev, 0, false);
    i2c_ll_disable_intr_mask(i2c->dev, I2C_LL_INTR_MASK);
    i2c_ll_clr_intsts_mask(i2c->dev, I2C_LL_INTR_MASK);

    if (i2c->intr_handle) {
        esp_intr_free(i2c->intr_handle);
        i2c->intr_handle = NULL;
    }

    if(i2c->task_handle){
        vTaskDelete(i2c->task_handle);
        i2c->task_handle = NULL;
    }

#if I2C_SLAVE_USE_RX_QUEUE
    if (i2c->rx_queue) {
        vQueueDelete(i2c->rx_queue);
        i2c->rx_queue = NULL;
    }
#else
    if (i2c->rx_ring_buf) {
        vRingbufferDelete(i2c->rx_ring_buf);
        i2c->rx_ring_buf = NULL;
    }
#endif

    if (i2c->tx_queue) {
        vQueueDelete(i2c->tx_queue);
        i2c->tx_queue = NULL;
    }

    if (i2c->event_queue) {
        vQueueDelete(i2c->event_queue);
        i2c->event_queue = NULL;
    }

    i2c->rx_data_count = 0;
}

static bool i2c_slave_set_frequency(i2c_slave_struct_t * i2c, uint32_t clk_speed)
{
    if (i2c == NULL) {
        log_e("no control buffer");
        return false;
    }
    if(clk_speed > 1100000UL){
        clk_speed = 1100000UL;
    }

    // Adjust Fifo thresholds based on frequency
    uint32_t a = (clk_speed / 50000L) + 2;
    log_d("Fifo thresholds: rx_fifo_full = %d, tx_fifo_empty = %d", SOC_I2C_FIFO_LEN - a, a);

    i2c_clk_cal_t clk_cal;
#if SOC_I2C_SUPPORT_APB
    i2c_ll_cal_bus_clk(APB_CLK_FREQ, clk_speed, &clk_cal);
    i2c_ll_set_source_clk(i2c->dev, I2C_SCLK_APB);            /*!< I2C source clock from APB, 80M*/
#elif SOC_I2C_SUPPORT_XTAL
    i2c_ll_cal_bus_clk(XTAL_CLK_FREQ, clk_speed, &clk_cal);
    i2c_ll_set_source_clk(i2c->dev, I2C_SCLK_XTAL);           /*!< I2C source clock from XTAL, 40M */
#endif
    i2c_ll_set_txfifo_empty_thr(i2c->dev, a);
    i2c_ll_set_rxfifo_full_thr(i2c->dev, SOC_I2C_FIFO_LEN - a);
    i2c_ll_set_bus_timing(i2c->dev, &clk_cal);
    i2c_ll_set_filter(i2c->dev, 3);
    return true;
}

static void i2c_slave_delay_us(uint64_t us)
{
    uint64_t m = esp_timer_get_time();
    if (us) {
        uint64_t e = (m + us);
        if (m > e) { //overflow
            while ((uint64_t)esp_timer_get_time() > e);
        }
        while ((uint64_t)esp_timer_get_time() < e);
    }
}

static void i2c_slave_gpio_mode(int8_t pin, gpio_mode_t mode)
{
    gpio_config_t conf = {
        .pin_bit_mask = 1LL << pin,
        .mode = mode,
        .pull_up_en = GPIO_PULLUP_ENABLE,
        .pull_down_en = GPIO_PULLDOWN_DISABLE,
        .intr_type = GPIO_INTR_DISABLE
    };
    gpio_config(&conf);
}

static bool i2c_slave_check_line_state(int8_t sda, int8_t scl)
{
    if (sda < 0 || scl < 0) {
        return false;//return false since there is nothing to do
    }
    // if the bus is not 'clear' try the cycling SCL until SDA goes High or 9 cycles
    gpio_set_level(sda, 1);
    gpio_set_level(scl, 1);
    i2c_slave_gpio_mode(sda, GPIO_MODE_INPUT | GPIO_MODE_DEF_OD);
    i2c_slave_gpio_mode(scl, GPIO_MODE_INPUT | GPIO_MODE_DEF_OD);
    gpio_set_level(scl, 1);

    if (!gpio_get_level(sda) || !gpio_get_level(scl)) { // bus in busy state
        log_w("invalid state sda(%d)=%d, scl(%d)=%d", sda, gpio_get_level(sda), scl, gpio_get_level(scl));
        for (uint8_t a=0; a<9; a++) {
            i2c_slave_delay_us(5);
            if (gpio_get_level(sda) && gpio_get_level(scl)) { // bus recovered
                log_w("Recovered after %d Cycles",a);
                gpio_set_level(sda,0); // start
                i2c_slave_delay_us(5);
                for (uint8_t a=0;a<9; a++) {
                    gpio_set_level(scl,1);
                    i2c_slave_delay_us(5);
                    gpio_set_level(scl,0);
                    i2c_slave_delay_us(5);
                }
                gpio_set_level(scl,1);
                i2c_slave_delay_us(5);
                gpio_set_level(sda,1); // stop
                break;
            }
            gpio_set_level(scl, 0);
            i2c_slave_delay_us(5);
            gpio_set_level(scl, 1);
        }
    }

    if (!gpio_get_level(sda) || !gpio_get_level(scl)) { // bus in busy state
        log_e("Bus Invalid State, Can't init sda=%d, scl=%d",gpio_get_level(sda),gpio_get_level(scl));
        return false; // bus is busy
    }
    return true;
}

static bool i2c_slave_attach_gpio(i2c_slave_struct_t * i2c, int8_t sda, int8_t scl)
{
    if (i2c == NULL) {
        log_e("no control block");
        return false;
    }
    
    if ((sda < 0)||( scl < 0)) {
        log_e("bad pins sda=%d, scl=%d",sda,scl);
        return false;
    }

    i2c->scl = scl;
    gpio_set_level(scl, 1);
    i2c_slave_gpio_mode(scl, GPIO_MODE_INPUT_OUTPUT_OD);
    gpio_matrix_out(scl, I2C_SCL_IDX(i2c->num), false, false);
    gpio_matrix_in(scl, I2C_SCL_IDX(i2c->num), false);

    i2c->sda = sda;
    gpio_set_level(sda, 1);
    i2c_slave_gpio_mode(sda, GPIO_MODE_INPUT_OUTPUT_OD);
    gpio_matrix_out(sda, I2C_SDA_IDX(i2c->num), false, false);
    gpio_matrix_in(sda, I2C_SDA_IDX(i2c->num), false);

    return true;
}

static bool i2c_slave_detach_gpio(i2c_slave_struct_t * i2c)
{
    if (i2c == NULL) {
        log_e("no control Block");
        return false;
    }
    if (i2c->scl >= 0) {
        gpio_matrix_out(i2c->scl, 0x100, false, false);
        gpio_matrix_in(0x30, I2C_SCL_IDX(i2c->num), false);
        i2c_slave_gpio_mode(i2c->scl, GPIO_MODE_INPUT);
        i2c->scl = -1; // un attached
    }
    if (i2c->sda >= 0) {
        gpio_matrix_out(i2c->sda, 0x100, false, false);
        gpio_matrix_in(0x30, I2C_SDA_IDX(i2c->num), false);
        i2c_slave_gpio_mode(i2c->sda, GPIO_MODE_INPUT);
        i2c->sda = -1; // un attached
    }
    return true;
}

static bool i2c_slave_send_event(i2c_slave_struct_t * i2c, i2c_slave_queue_event_t* event)
{
    bool pxHigherPriorityTaskWoken = false;
    if(i2c->event_queue) {
        if(xQueueSendFromISR(i2c->event_queue, event, (BaseType_t * const)&pxHigherPriorityTaskWoken) != pdTRUE){
            //log_e("event_queue_full");
        }
    }
    return pxHigherPriorityTaskWoken;
}

static bool i2c_slave_handle_tx_fifo_empty(i2c_slave_struct_t * i2c)
{
    bool pxHigherPriorityTaskWoken = false;
    uint32_t d = 0, moveCnt = i2c_ll_get_txfifo_len(i2c->dev);
    while (moveCnt > 0) { // read tx queue until Fifo is full or queue is empty
        if(xQueueReceiveFromISR(i2c->tx_queue, &d, (BaseType_t * const)&pxHigherPriorityTaskWoken) == pdTRUE){
            i2c_ll_write_txfifo(i2c->dev, (uint8_t*)&d, 1);
            moveCnt--;
        } else {
            i2c_ll_slave_disable_tx_it(i2c->dev);
            break;
        }
    }
    return pxHigherPriorityTaskWoken;
}

static bool i2c_slave_handle_rx_fifo_full(i2c_slave_struct_t * i2c, uint32_t len)
{
#if I2C_SLAVE_USE_RX_QUEUE
    uint32_t d = 0;
#else
    uint8_t data[SOC_I2C_FIFO_LEN];
#endif
    bool pxHigherPriorityTaskWoken = false;
#if I2C_SLAVE_USE_RX_QUEUE
    while (len > 0) {
        i2c_ll_read_rxfifo(i2c->dev, (uint8_t*)&d, 1);
        if(xQueueSendFromISR(i2c->rx_queue, &d, (BaseType_t * const)&pxHigherPriorityTaskWoken) != pdTRUE){
            log_e("rx_queue_full");
        } else {
            i2c->rx_data_count++;
        }
        if (--len == 0) {
            len = i2c_ll_get_rxfifo_cnt(i2c->dev);
        }
#else
    if(len){
        i2c_ll_read_rxfifo(i2c->dev, data, len);
        if(xRingbufferSendFromISR(i2c->rx_ring_buf, (void*) data, len, (BaseType_t * const)&pxHigherPriorityTaskWoken) != pdTRUE){
            log_e("rx_ring_buf_full");
        } else {
            i2c->rx_data_count += len;
        }
#endif
    }
    return pxHigherPriorityTaskWoken;
}

static void i2c_slave_isr_handler(void* arg)
{
    bool pxHigherPriorityTaskWoken = false;
    i2c_slave_struct_t * i2c = (i2c_slave_struct_t *) arg; // recover data

    uint32_t activeInt = i2c_ll_get_intsts_mask(i2c->dev);
    i2c_ll_clr_intsts_mask(i2c->dev, activeInt);
    uint8_t rx_fifo_len = i2c_ll_get_rxfifo_cnt(i2c->dev);
    bool slave_rw = i2c_ll_slave_rw(i2c->dev);

    if(activeInt & I2C_RXFIFO_WM_INT_ENA){ // RX FiFo Full
        pxHigherPriorityTaskWoken |= i2c_slave_handle_rx_fifo_full(i2c, rx_fifo_len);
        i2c_ll_slave_enable_rx_it(i2c->dev);//is this necessary?
    }

    if(activeInt & I2C_TRANS_COMPLETE_INT_ENA){ // STOP
        if(rx_fifo_len){ //READ RX FIFO
            pxHigherPriorityTaskWoken |= i2c_slave_handle_rx_fifo_full(i2c, rx_fifo_len);
        }
        if(i2c->rx_data_count){ //WRITE or RepeatedStart
            //SEND RX Event
            i2c_slave_queue_event_t event;
            event.event = I2C_SLAVE_EVT_RX;
            event.stop = !slave_rw;
            event.param = i2c->rx_data_count;
            pxHigherPriorityTaskWoken |= i2c_slave_send_event(i2c, &event);
            //Zero RX count
            i2c->rx_data_count = 0;
        }
        if(slave_rw){ // READ
#if CONFIG_IDF_TARGET_ESP32
            if(i2c->dev->status_reg.scl_main_state_last == 6){
                //SEND TX Event
                i2c_slave_queue_event_t event;
                event.event = I2C_SLAVE_EVT_TX;
                pxHigherPriorityTaskWoken |= i2c_slave_send_event(i2c, &event);
            }
#else
            //reset TX data
            i2c_ll_txfifo_rst(i2c->dev);
            uint8_t d;
            while (xQueueReceiveFromISR(i2c->tx_queue, &d, (BaseType_t * const)&pxHigherPriorityTaskWoken) == pdTRUE) ;//flush partial write
#endif
        }
    }

#ifndef CONFIG_IDF_TARGET_ESP32
    if(activeInt & I2C_SLAVE_STRETCH_INT_ENA){ // STRETCH
        i2c_stretch_cause_t cause = i2c_ll_stretch_cause(i2c->dev);
        if(cause == I2C_STRETCH_CAUSE_MASTER_READ){
            //on C3 RX data dissapears with repeated start, so we need to get it here
            if(rx_fifo_len){
                pxHigherPriorityTaskWoken |= i2c_slave_handle_rx_fifo_full(i2c, rx_fifo_len);
            }
            //SEND TX Event
            i2c_slave_queue_event_t event;
            event.event = I2C_SLAVE_EVT_TX;
            pxHigherPriorityTaskWoken |= i2c_slave_send_event(i2c, &event);
            //will clear after execution
        } else if(cause == I2C_STRETCH_CAUSE_TX_FIFO_EMPTY){
            pxHigherPriorityTaskWoken |= i2c_slave_handle_tx_fifo_empty(i2c);
            i2c_ll_stretch_clr(i2c->dev);
        } else if(cause == I2C_STRETCH_CAUSE_RX_FIFO_FULL){
            pxHigherPriorityTaskWoken |= i2c_slave_handle_rx_fifo_full(i2c, rx_fifo_len);
            i2c_ll_stretch_clr(i2c->dev);
        }
    }
#endif

    if(activeInt & I2C_TXFIFO_WM_INT_ENA){ // TX FiFo Empty
        pxHigherPriorityTaskWoken |= i2c_slave_handle_tx_fifo_empty(i2c);
    }

    if(pxHigherPriorityTaskWoken){
        portYIELD_FROM_ISR();
    }
}

static size_t i2c_slave_read_rx(i2c_slave_struct_t * i2c, uint8_t * data, size_t len){
    if(!len){
        return 0;
    }
#if I2C_SLAVE_USE_RX_QUEUE
    uint8_t d = 0;
    BaseType_t res = pdTRUE;
    for(size_t i=0; i<len; i++) {
        if(data){
            res = xQueueReceive(i2c->rx_queue, &data[i], 0);
        } else {
            res = xQueueReceive(i2c->rx_queue, &d, 0);
        }
        if (res != pdTRUE) {
            log_e("Read Queue(%u) Failed", i);
            len = i;
            break;
        }
    }
    return (data)?len:0;
#else
    size_t  dlen = 0, 
            to_read = len, 
            so_far = 0, 
            available = 0;
    uint8_t * rx_data = NULL;

    vRingbufferGetInfo(i2c->rx_ring_buf, NULL, NULL, NULL, NULL, &available);
    if(available < to_read){
        log_e("Less available than requested. %u < %u", available, len);
        to_read = available;
    }

    while(to_read){
        dlen = 0;
        rx_data = (uint8_t *)xRingbufferReceiveUpTo(i2c->rx_ring_buf, &dlen, 0, to_read);
        if(!rx_data){
            log_e("Receive %u Failed", to_read);
            return so_far;
        }
        if(data){
            memcpy(data+so_far, rx_data, dlen);
        }
        vRingbufferReturnItem(i2c->rx_ring_buf, rx_data);
        so_far+=dlen;
        to_read-=dlen;
    }
    return (data)?so_far:0;
#endif
}

static void i2c_slave_task(void *pv_args)
{
    i2c_slave_struct_t * i2c = (i2c_slave_struct_t *)pv_args;
    i2c_slave_queue_event_t event;
    size_t len = 0;
    bool stop = false;
    uint8_t * data = NULL;
    for(;;){
        if(xQueueReceive(i2c->event_queue, &event, portMAX_DELAY) == pdTRUE){
            // Write
            if(event.event == I2C_SLAVE_EVT_RX){
                len = event.param;
                stop = event.stop;
                data = (len > 0)?(uint8_t*)malloc(len):NULL;

                if(len && data == NULL){
                    log_e("Malloc (%u) Failed", len);
                }
                len = i2c_slave_read_rx(i2c, data, len);
                if(i2c->receive_callback){
                    i2c->receive_callback(i2c->num, data, len, stop, i2c->arg);
                }
                free(data);

            // Read
            } else if(event.event == I2C_SLAVE_EVT_TX){
                if(i2c->request_callback){
                    i2c->request_callback(i2c->num, i2c->arg);
                }
                i2c_ll_stretch_clr(i2c->dev);
            }
        }
    }
    vTaskDelete(NULL);
}