/* =============================================================================
 * bsp_usart.c - 串口 DMA 接收板级支持包(USART1/3/6)
 * 职责:
 *   1. usartX_init()        任务上下文调用:配置 RX 循环 DMA + 空闲中断,
 *                           注册"整帧"回调(帧 = 两次空闲之间的字节)
 *   2. usartX_idle_isr()    由 stm32f4xx_it.c 的 USER CODE 区调用(需在
 *                           HAL_UART_IRQHandler 之前):读 NDTR 算帧长,
 *                           清 F4 DMA 流事件标志后重启 DMA,递交回调
 *   3. usartX_tx_dma_*()    TX DMA 发送(缓冲须保持有效直到发送完成)
 * 数据流:  DR16(USART3)/裁判(USART6)/视觉(USART1) --IDLE ISR--> 回调
 * 关键细节:
 *   - 采用单缓冲循环 DMA + IDLE 重启(DJI 官方风格),不使用双缓冲
 *   - F4 手册要求重启 DMA 流前必须清除该流全部事件标志,否则只收到第一帧
 *   - usart3_init 会把字长改为 9B(CubeMX 生成的 8B+偶校验只有 7 个数据位,
 *     DR16 帧需要 8 数据位+偶校验)
 * ========================================================================== */
#include "bsp_usart.h"
#include "main.h"

extern UART_HandleTypeDef huart1;
extern DMA_HandleTypeDef hdma_usart1_tx;
extern DMA_HandleTypeDef hdma_usart1_rx;
extern UART_HandleTypeDef huart3;
extern DMA_HandleTypeDef hdma_usart3_rx;
extern UART_HandleTypeDef huart6;
extern DMA_HandleTypeDef hdma_usart6_rx;
extern DMA_HandleTypeDef hdma_usart6_tx;

/* ==========================================================================
 * 单缓冲循环 DMA + 空闲中断重启接收(DJI 官方风格)
 * 每路串口接收配置:RX 走循环 DMA,空闲中断里读 NDTR 计算本帧长度,
 * 复位 NDTR 后继续接收,并通过注册的回调把整帧递交给使用者。
 * 回调在中断上下文执行,应尽量短(可拷贝数据/通知任务)。
 * ========================================================================== */

#define USART_RX_SLOT_MAX 3

typedef struct
{
    UART_HandleTypeDef * huart;
    uint8_t * rx_buf;
    uint16_t buf_num;
    usart_rx_callback_f callback;
} usart_rx_slot_t;

static usart_rx_slot_t usart_rx_slots[USART_RX_SLOT_MAX];

/* 诊断计数(空串口事件次数/最近帧长),debug_task 打印 */
volatile uint32_t dbg_usart1_idle = 0;
volatile uint32_t dbg_usart3_idle = 0;
volatile uint32_t dbg_usart6_idle = 0;
volatile uint16_t dbg_usart3_last_len = 0;
volatile uint16_t dbg_usart6_last_len = 0;

static usart_rx_slot_t * usart_rx_slot_find(UART_HandleTypeDef * huart)
{
    for (uint8_t i = 0; i < USART_RX_SLOT_MAX; i++)
        if (usart_rx_slots[i].huart == huart)
            return &usart_rx_slots[i];
    return NULL;
}

static void usart_rx_dma_start(usart_rx_slot_t * slot, DMA_HandleTypeDef * hdma_rx)
{
    __HAL_DMA_DISABLE(hdma_rx);
    while (hdma_rx->Instance->CR & DMA_SxCR_EN)
        ;

    /* F4 手册要求:重新使能流之前必须清除该流全部事件标志,
     * 否则残留标志会导致流重启后不工作(表现为只收到第一帧) */
    {
        DMA_TypeDef * ctl = (DMA_TypeDef *)((uint32_t)hdma_rx->Instance & ~(0x3FFU));
        uint32_t stream_no = ((uint32_t)hdma_rx->Instance - (uint32_t)DMA1_Stream0) / 24U;
        if (stream_no < 4U)
            ctl->LIFCR = 0x3FUL << (6U * stream_no);
        else
            ctl->HIFCR = 0x3FUL << (6U * (stream_no - 4U));
    }

    hdma_rx->Instance->PAR = (uint32_t) & (slot->huart->Instance->DR);
    /* 不使用 DMA 半满/全满中断,只靠空闲中断取帧 */
    hdma_rx->Instance->CR &= ~(DMA_SxCR_HTIE | DMA_SxCR_TCIE);
    hdma_rx->Instance->NDTR = slot->buf_num;
    hdma_rx->Instance->M0AR = (uint32_t)slot->rx_buf;
    __HAL_DMA_ENABLE(hdma_rx);
}

static void usart_common_rx_init(
    UART_HandleTypeDef * huart, DMA_HandleTypeDef * hdma_rx, uint8_t * rx_buf, uint16_t dma_buf_num,
    usart_rx_callback_f callback)
{
    usart_rx_slot_t * slot = usart_rx_slot_find(huart);
    if (slot == NULL)
    {
        for (uint8_t i = 0; i < USART_RX_SLOT_MAX; i++)
            if (usart_rx_slots[i].huart == NULL)
            {
                slot = &usart_rx_slots[i];
                break;
            }
        if (slot == NULL)
            return;
    }
    slot->huart = huart;
    slot->rx_buf = rx_buf;
    slot->buf_num = dma_buf_num;
    slot->callback = callback;

    /* 使能 DMA 接收请求与空闲中断 */
    SET_BIT(huart->Instance->CR3, USART_CR3_DMAR);
    __HAL_UART_ENABLE_IT(huart, UART_IT_IDLE);

    usart_rx_dma_start(slot, hdma_rx);
}

/* 空闲中断处理:取帧长,复位 DMA,回调递交(在各 USARTx_IRQHandler 的 USER CODE 区调用) */
static void usart_idle_process(usart_rx_slot_t * slot, DMA_HandleTypeDef * hdma_rx)
{
    if (slot == NULL || slot->callback == NULL)
        return;

    __HAL_UART_CLEAR_IDLEFLAG(slot->huart);

    uint16_t recv_len = slot->buf_num - hdma_rx->Instance->NDTR;
    usart_rx_dma_start(slot, hdma_rx);
    if (hdma_rx == &hdma_usart3_rx)
        dbg_usart3_last_len = recv_len;
    else if (hdma_rx == &hdma_usart6_rx)
        dbg_usart6_last_len = recv_len;
    if (recv_len > 0)
        slot->callback(slot->rx_buf, recv_len);
}

/* --- 三路串口的 IDLE 中断入口,由 stm32f4xx_it.c 调用 --- */
void usart1_idle_isr(void)
{
    dbg_usart1_idle++;
    usart_idle_process(usart_rx_slot_find(&huart1), &hdma_usart1_rx);
}
void usart3_idle_isr(void)
{
    dbg_usart3_idle++;
    usart_idle_process(usart_rx_slot_find(&huart3), &hdma_usart3_rx);
}
void usart6_idle_isr(void)
{
    dbg_usart6_idle++;
    usart_idle_process(usart_rx_slot_find(&huart6), &hdma_usart6_rx);
}

int usart_rx_register(UART_HandleTypeDef * huart, usart_rx_callback_f callback)
{
    usart_rx_slot_t * slot = usart_rx_slot_find(huart);
    if (slot == NULL)
        return -1;
    slot->callback = callback;
    return 0;
}

/* ==========================================================================
 * 各串口接收初始化(在任务上下文调用;DMA/NVIC 已由 CubeMX 初始化)
 * ========================================================================== */

/* 视觉上位机串口(4pin 口 UART2),本工程暂未使用,保留接口 */
void usart1_init(uint8_t * rx_buf, uint16_t dma_buf_num, usart_rx_callback_f callback)
{
    usart_common_rx_init(&huart1, &hdma_usart1_rx, rx_buf, dma_buf_num, callback);
}

/* DR16 遥控器接收机专用(100000-8E1)
 * CubeMX 生成的 WordLength=8B 在奇偶校验下只有 7 个数据位,
 * DR16 帧需要 8 数据位+偶校验,必须改为 9 位字长后重新初始化 */
void usart3_init(uint8_t * rx_buf, uint16_t dma_buf_num, usart_rx_callback_f callback)
{
    CLEAR_BIT(huart3.Instance->CR1, USART_CR1_UE); /* 先关串口再改字长 */
    huart3.Init.WordLength = UART_WORDLENGTH_9B;
    if (HAL_UART_Init(&huart3) != HAL_OK)
        return;

    usart_common_rx_init(&huart3, &hdma_usart3_rx, rx_buf, dma_buf_num, callback);
}

/* 图传链路/裁判系统串口(3pin 口 UART1) */
void usart6_init(uint8_t * rx_buf, uint16_t dma_buf_num, usart_rx_callback_f callback)
{
    usart_common_rx_init(&huart6, &hdma_usart6_rx, rx_buf, dma_buf_num, callback);
}

/* ==========================================================================
 * 发送(TX DMA,发送缓冲须保持有效直至传输完成)
 * ========================================================================== */

void usart1_tx_dma_init(void)
{
    SET_BIT(huart1.Instance->CR3, USART_CR3_DMAT);
}

void usart1_tx_dma_enable(uint8_t * data, uint16_t len)
{
    __HAL_DMA_DISABLE(&hdma_usart1_tx);
    while (hdma_usart1_tx.Instance->CR & DMA_SxCR_EN)
        ;
    hdma_usart1_tx.Instance->M0AR = (uint32_t)data;
    hdma_usart1_tx.Instance->NDTR = len;
    __HAL_DMA_ENABLE(&hdma_usart1_tx);
}

void usart6_tx_dma_enable(uint8_t * data, uint16_t len)
{
    SET_BIT(huart6.Instance->CR3, USART_CR3_DMAT);

    __HAL_DMA_DISABLE(&hdma_usart6_tx);
    while (hdma_usart6_tx.Instance->CR & DMA_SxCR_EN)
        ;
    hdma_usart6_tx.Instance->M0AR = (uint32_t)data;
    hdma_usart6_tx.Instance->NDTR = len;
    __HAL_DMA_ENABLE(&hdma_usart6_tx);
}