#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "bsp_share.h"

struct shmem_fd shmem_fd;

#define SHMEM_WR_FLAG 0x1122
#define SHMEM_RD_FLAG 0x3344

/* CRC-16 表 */
static const unsigned short Lookup[256] = {
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
    0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
    0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
    0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
    0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
    0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
    0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
    0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
    0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
    0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
    0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
    0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
    0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
    0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
    0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
    0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
    0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
    0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
    0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
    0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
    0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
    0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
    0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
    0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
    0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
    0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
    0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
    0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
    0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
    0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
    0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
    0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040};

static unsigned short crc16(unsigned char *p, int len)
{
    unsigned short crc = 0;
    int zero = 1;

    if (len <= 0)
        return crc;

    while (len-- > 0)
    {
        if (*p != 0)
            zero = 0;
        crc = Lookup[(crc & 0xff) ^ (*p++)] ^ (crc >> 8);
    }

    if (zero)
        crc = 0x5678; /* 若全为0，crc返回就不要为零 */
    return crc;
}

int shmem_read_crc(struct shmem_fd *shmem_fd, void *buf, int len,
                   int waiting, unsigned short *crc)
{
    volatile struct shmem_block *linux_read = shmem_fd->linux_read;
    unsigned short _crc;

    if (!buf)
        return -EINVAL;

    if (len > shmem_fd->linux_read_data_len)
    {
        printf("len(%d) != MAX_SHMEM_RD_DATA_LEN(%d)\n",
               len, shmem_fd->linux_read_data_len);
        return -EINVAL;
    }

    if (linux_read->flag == SHMEM_RD_FLAG)
        goto read;

    if (waiting < 0)
    {
        while (linux_read->flag != SHMEM_RD_FLAG)
            ;
    }
    else if (waiting > 0)
    {
        while (waiting-- && linux_read->flag != SHMEM_RD_FLAG)
            usleep(waiting);
    }

    if (linux_read->flag != SHMEM_RD_FLAG)
        return -EBUSY;

read:
    _crc = crc16((void *)linux_read->data, linux_read->len);
    if (_crc != linux_read->crc)
    {
        printf("crc(%x) != linux_read->crc(%x)\n",
               _crc, linux_read->crc);
        return -EIO;
    }

    if (len > linux_read->len)
        len = linux_read->len;

    memcpy(buf, (const void *)linux_read->data, len);
    linux_read->flag = 0;

    *crc = _crc;
    return len;
}

int shmem_write_crc(struct shmem_fd *shmem_fd, void *buf, int len,
                    int waiting, unsigned short *crc)
{
    volatile struct shmem_block *linux_write = shmem_fd->linux_write;
    unsigned short _crc;

    if (!buf)
        return -EINVAL;

    if (len > shmem_fd->linux_write_data_len)
    {
        printf("len(%d) != MAX_SHMEM_WR_DATA_LEN(%d)\n",
               len, shmem_fd->linux_write_data_len);
        return -EINVAL;
    }

    if (linux_write->flag)
        goto write;

    if (waiting < 0)
    {
        while (linux_write->flag)
            ;
    }
    else if (waiting > 0)
    {
        while (waiting-- && linux_write->flag)
            usleep(waiting);
    }

    if (linux_write->flag == SHMEM_WR_FLAG)
        return -EBUSY;

write:
    memcpy((void *)linux_write->data, buf, len);
    _crc = crc16((void *)linux_write->data, len);

    linux_write->crc = _crc;
    linux_write->len = len;
    linux_write->flag = SHMEM_WR_FLAG;

    *crc = _crc;
    return len;
}

int shmem_read(struct shmem_fd *shmem_fd, void *buf, int len, int waiting)
{
    volatile struct shmem_block *linux_read = shmem_fd->linux_read;

    if (!buf || len > shmem_fd->linux_read_data_len)
        return -1;

    if (linux_read->flag == SHMEM_RD_FLAG)
        goto read;

    if (waiting < 0)
    {
        while (linux_read->flag != SHMEM_RD_FLAG)
            ;
    }
    else if (waiting > 0)
    {
        while (waiting-- && linux_read->flag != SHMEM_RD_FLAG)
            usleep(waiting);
    }

    if (linux_read->flag != SHMEM_RD_FLAG)
        return -EBUSY;

read:
    if (len > linux_read->len)
        len = linux_read->len;
    memcpy(buf, (const void *)linux_read->data, len);
    linux_read->flag = 0;

    return 0;
}

int shmem_write(struct shmem_fd *shmem_fd, void *buf, int len, int waiting)
{
    volatile struct shmem_block *linux_write = shmem_fd->linux_write;

    if (!buf || len > shmem_fd->linux_write_data_len)
        return -1;

    if (linux_write->flag)
        goto write;

    if (waiting < 0)
    {
        while (linux_write->flag)
            ;
    }
    else if (waiting > 0)
    {
        while (waiting-- && linux_write->flag)
            usleep(waiting);
    }

    if (linux_write->flag == SHMEM_WR_FLAG)
        return -EBUSY;

write:
    memcpy((void *)linux_write->data, buf, len);
    linux_write->len = len;
    linux_write->flag = SHMEM_WR_FLAG;

    return 0;
}

#define ARV_SHMEM_REGION_LEN 0x10

int shmem_init(struct shmem_fd *shmem_fd)
{
    int fd;
    void *shmem;
    int ret;

    fd = open("/dev/arv-shmem", O_RDWR);
    if (fd == -1)
    {
        printf("can not open file /dev/arv-shmem\n");
        return -1;
    }

    ret = ioctl(fd, ARV_SHMEM_REGION_LEN, &shmem_fd->shmem_len);
    if (ret)
    {
        printf("failed to get the len of shmem\n");
        return -1;
    }
    printf("shmem len: 0x%x\n", shmem_fd->shmem_len);

    shmem_fd->linux_write_len = max_shmem_wr_len(shmem_fd->shmem_len);
    shmem_fd->linux_read_len = max_shmem_rd_len(shmem_fd->shmem_len);
    shmem_fd->linux_write_data_len = max_shmem_wr_data_len(shmem_fd->shmem_len);
    shmem_fd->linux_read_data_len = max_shmem_rd_data_len(shmem_fd->shmem_len);

    shmem = mmap(NULL, shmem_fd->shmem_len, PROT_READ | PROT_WRITE,
                 MAP_SHARED, fd, 0);
    if (shmem <= 0)
    {
        printf("failed to get shmem\n");
        return -1;
    }
    printf("mmap: %llx\n", (unsigned long long)shmem);

    shmem_fd->fd = fd;
    shmem_fd->linux_write = (struct shmem_block *)shmem;
    shmem_fd->linux_read = (struct shmem_block *)(shmem + shmem_fd->linux_write_len);

    return 0;
}

void shmem_exit(struct shmem_fd *shmem_fd)
{
    munmap(shmem_fd->linux_write, shmem_fd->shmem_len);
    close(shmem_fd->fd);
}