/*
 * This file is part of the libusbhost library
 * hosted at http://github.com/libusbhost/libusbhost
 *
 * Copyright (C) 2015 Amir Hammad <amir.hammad@hotmail.com>
 *
 *
 * libusbhost is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef __SERIAL_H__
#define __SERIAL_H__

#include <stdint.h>
#include <stdarg.h>
#include <errno.h>

#include "global.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 */
    ssize_t cur_packet;
    int retransmit_rq;
    int wraparound;

    /* 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[512];
};

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

enum ctrl_pkt_type {
    CTRL_PKT_RESET = 1,
    CTRL_PKT_ACK = 2,
    CTRL_PKT_RETRANSMIT = 3,
};

struct __attribute__((__packed__)) ctrl_pkt {
    uint8_t type;
    uint8_t orig_id;
};

extern volatile struct dma_tx_buf usart_tx_buf;

void usart_dma_init(void);
int usart_dma_fifo_push(volatile struct dma_tx_buf *buf, uint8_t c);
int usart_send_packet_nonblocking(struct ll_pkt *pkt, size_t pkt_len);
int usart_ack_packet(uint8_t idx);

#endif // __SERIAL_H__