GC23005/Component/Modbus/modbus_encoder.c

#include "modbus_encoder.h"

//======================================= Modbus Encoder API ====================================//
static const unsigned char BinToAscTab[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    'A', 'B', 'C', 'D', 'E', 'F' };

static const unsigned char  CRCTblHi[] = {
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
};

static const unsigned char CRCTblLo[] = {
    0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
    0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
    0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
    0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
    0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
    0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
    0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
    0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
    0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
    0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
    0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
    0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
    0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
    0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
    0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
    0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
    0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
    0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
    0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
    0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
    0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
    0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
    0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
    0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
    0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
    0x43, 0x83, 0x41, 0x81, 0x80, 0x40
};

/**
 * 计算累加和校验
 * 
 * @author LXZ (2018-12-03)
 * 
 * @param dat 
 * @param length 
 * 
 * @return unsigned char 
 */
static unsigned char modbus_calc_lrc(unsigned char *dat, int length)
{
    unsigned char lrc = 0;

    while (length > 0)
    {
        length--;
        lrc += *dat;
        dat++;
    }
    return (~lrc) + 1;
}

/**
 * 计算累加和校验
 * 
 * @author LXZ (2018-12-03)
 * 
 * @param dat 
 * @param length 
 * 
 * @return unsigned char 
 */
static unsigned short modbus_calc_crc(unsigned char *dat, int length)
{
    unsigned char lo = 0xff, hi = 0xff;
    unsigned char index = 0;

    while (length > 0)
    {
        length--;
        index = hi ^ (*dat);
        hi = lo ^ CRCTblHi[index];
        lo = CRCTblLo[index];
        dat++;
    }
    return 0x0100 * lo + hi;
}

/**
 * rtu协议的编码
 * 
 * @author lxz 
 * 
 * @param dst   目标存放缓冲
 * @param src   原始包数据
 * @param length 数据长度
 * 
 * @return int  解码后的有效长度
 */
static int modbus_encoder_rtu_encode(unsigned char *dst, unsigned char *src, int length)
{
    unsigned short crc = modbus_calc_crc(src, length);

    //需要时就复制源数据
    if (dst != src)
    {
        int index = 0;
        while (index < length)
        {
            dst[index] = src[index];
            index++;
        }
    }

    dst[length++] = crc;
    dst[length++] = crc >> 8;
    return length;
}

/**
 * 读写长度修正
 * 
 * @author lxz 
 * 
 * @param dir  方向，解码是0，编码是1
 * @param length 源长度
 * 
 * @return int 
 */
static int modbus_endcoder_rtu_length_calc(int dir, int length)
{
    if (dir)
    {
        length = length + 2;
    } else
    {
        length = length - 2;
    }
    return length;
}

/**
 * rtu协议的解码
 * 
 * @author lxz 
 * 
 * @param dst       目标存放缓冲
 * @param src       原始包数据
 * @param length    数据长度
 * 
 * @return int      编码后的长度
 */
static int modbus_encoder_rtu_decode(unsigned char *dst, unsigned char *src, int length)
{
    if (length < 4)
    {
        return -1;
    }

    if (modbus_calc_crc(src, length) == 0)
    {
        //需要时就复制源数据
        if (dst != src)
        {
            int index = 0;
            while (index < length)
            {
                dst[index] = src[index];
                index++;
            }
        }
        return length - 2;
    }

    return 0;
}

/**
 * ascii协议的编码
 * 
 * @author lxz 
 * 
 * @param dst   目标存放缓冲
 * @param src   原始包数据
 * @param length 数据长度
 * 
 * @return int  解码后的有效长度
 */
static int modbus_encoder_ascii_encode(unsigned char *dst, unsigned char *src, int length)
{
    int index = length * 2 + 1;

    //计算累加和
    unsigned char lrc = modbus_calc_lrc(src, length);

    //从后面编码可以保证前面不会被覆盖
    while (length > 0)
    {
        length--;
        dst[(length << 1) + 1] = BinToAscTab[(src[length] >> 4) & 0x0f];
        dst[(length << 1) + 2] = BinToAscTab[src[length] & 0x0f];
    }

    //首字节肯定是':'
    dst[0] = ':';


    /**
     * 加上结尾
     */
    dst[index++] = BinToAscTab[(lrc >> 4) & 0x0f];
    dst[index++] = BinToAscTab[lrc & 0x0f];
    dst[index++] = 0x0D;
    dst[index++] = 0x0A;

    return index;
}

/**
 * ascii读写长度修正
 * 
 * @author lxz 
 * 
 * @param dir      方向，解码是0，编码是1
 * @param length   源长度
 * 
 * @return int 
 */
static int modbus_endcoder_ascii_length_calc(int dir, int length)
{
    if (dir)
    {
        length = length * 2 + 5;
    } else
    {
        length = (length - 5) / 2;
    }
    return length;
}

/**
 * ascii协议的解码
 * 
 * @author lxz 
 * 
 * @param dst       目标存放缓冲
 * @param src       原始包数据
 * @param length    数据长度
 * 
 * @return int      编码后的长度
 */
static int modbus_encoder_ascii_decode(unsigned char *dst, unsigned char *src, int length)
{
    int index = 0;
    int res = 0;
    unsigned char dat = 0;

    //不符合长度与格式要求不能进行解码
    if (length < 9)
    {
        return -1;
    }
    if (*src != ':' || src[length - 1] != 0x0A || src[length - 2] != 0x0D)
    {
        return -2;
    }

    //跳掉 ':'
    src++;
        length -= 3;

    //Ascii 解码成hex
    while (length > 1)
    {
        dat = 0;
        if (*src >= 'A' && *src <= 'F')
        {
            dat = *src - 'A' + 10;
        } else if (*src >= '0' && *src <= '9')
        {
            dat = *src - '0';
        }

        src++;
        dat <<= 4;

        if (*src >= 'A' && *src <= 'F')
        {
            dat |= *src - 'A' + 10;
        } else if (*src >= '0' && *src <= '9')
        {
            dat |= *src - '0';
        }

        src++;
        length -= 2;

        dst[index] = dat;
        index++;
    }

    //校验通过
    if (modbus_calc_lrc(dst, index) == 0)
    {
        res = index;
    }

    return res;
}

static const modbus_encoder_t modbus_rtu_encoder = {
    modbus_encoder_rtu_encode,
    modbus_encoder_rtu_decode,
    modbus_endcoder_rtu_length_calc
};
static const modbus_encoder_t modbus_ascii_encoder = {
    modbus_encoder_ascii_encode,
    modbus_encoder_ascii_decode,
    modbus_endcoder_ascii_length_calc
};


/**
 * 根据给定的类型数据缓冲来获取一个匹配的编码器，匹配原则是第一个字节，如果是':'并且最后两个字节是0x0D与0x0A 
 * 刚返回ASCII，否则就返回RTU 
 * 
 * @author lxz 
 * 
 * @param buffer 
 * @param length 
 * 
 * @return modbus_encoder_t* 
 */
modbus_encoder_t * modbus_encoder_match(unsigned char * buffer,int length)
{

    if (length < 4)
    {
        return 0;
    }
    if (buffer[0] == ':' && buffer[length - 2] == 0x0D && buffer[length - 1] == 0x0A)
    {             
        return (modbus_encoder_t * )&modbus_ascii_encoder;
    }
    return (modbus_encoder_t * )&modbus_rtu_encoder;
}

/**
 * 根据编号获取编码器，0是ASCII,1是RTU
 * 
 * @author lxz 
 * 
 * @param no 
 * 
 * @return modbus_encoder_t* 
 */
modbus_encoder_t * modbus_encoder_get(int no)
{
    if (no == MODBUS_ENCODER_ASCII)
    {
        return (modbus_encoder_t * )&modbus_ascii_encoder;
    }
    else if (no == MODBUS_ENCODER_RTU)
    {
        return (modbus_encoder_t * )&modbus_rtu_encoder;
    }
    return 0;
}