#ifndef __SERIAL_H__
#define __SERIAL_H__

#include <global.h>
#include <cobs.h>

struct dma_tx_buf {
    /* The following fields are accessed only from DMA ISR */
    ssize_t xfr_start; /* Start index of running DMA transfer */
    ssize_t xfr_end; /* End index of running DMA transfer plus one */
    bool wraparound;
    ssize_t xfr_next;
    bool ack;


    /* The following fields are written only from non-interrupt code */
    ssize_t wr_pos; /* Next index to be written */
    ssize_t wr_idx;
    ssize_t packet_end[8];

    /* The following may be accessed by anything */
    uint8_t data[256];
};

struct uart_dma_state {
    struct dma_tx_buf tx_buf;

    uint32_t retransmissions, packet_count;
    ErrorCode error;
    uint64_t last_error;
    uint64_t last_packet;
    uint64_t last_transmission;

    struct cobs_decode_state cobs_state;

    DMA_Channel_TypeDef *tx_dma_ch;
    USART_TypeDef *usart;

    uint8_t rx_buf[256];
    uint8_t addr;
};

struct __attribute__((__packed__)) ll_pkt {
    uint32_t crc32;
    /* CRC computed over entire packet starting here */
    uint8_t src;
    uint8_t dst;
    uint8_t pid;
    uint8_t type;
    uint8_t data[0];
};

#define SER_ADDR_BROADCAST 0xff

extern volatile struct uart_dma_state uart_st;

void uart_dma_init(USART_TypeDef *usart, DMA_Channel_TypeDef *tx_dma_ch, int addr);
int uart_send_packet_nonblocking(struct ll_pkt *pkt, size_t pkt_len);
int uart_ack_packet(uint8_t idx);
void uart_dma_interrupt(DMA_Channel_TypeDef *ch, uint32_t flags);
void uart_interrupt(uint32_t isr);

extern void uart_handle_user_packet(struct ll_pkt *pkt, size_t len);

#endif // __SERIAL_H__