1.校验多项式采用C语言：CRC-16； 2、输入数据流不定长，输入数据流放入txt文件中；输出存入到同一文件的下一行，后面2字节为校验码，采用小端格式； 3.画出程序流程图； 4.计算0x00-0xff的CRC校验码表：

1. CRC-16的C语言实现：

#include <stdio.h>
#include <stdint.h>

#define POLY 0x8005
#define INIT 0xffff

uint16_t crc16(uint8_t *data, uint16_t length)
{
    uint16_t crc = INIT;
    uint16_t i, j;

    for (i = 0; i < length; i++) {
        crc ^= (uint16_t)data[i];
        for (j = 0; j < 8; j++) {
            if (crc & 0x0001) {
                crc = (crc >> 1) ^ POLY;
            } else {
                crc = crc >> 1;
            }
        }
    }

    return crc;
}

int main(void)
{
    uint8_t data[] = {0x01, 0x02, 0x03, 0x04};
    uint16_t crc = crc16(data, sizeof(data));

    printf("CRC-16: 0x%04x\n", crc);

    return 0;
}

2. 实现过程：

- 读取输入文件，逐行读取每个数据流。
- 对每个数据流进行CRC-16校验，将校验码写入输出文件。
- 输出文件的格式为：输入数据流、校验码，每个数据流和校验码占用2个字节，使用小端格式。

示例代码：

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

#define POLY 0x8005
#define INIT 0xffff

uint16_t crc16(uint8_t *data, uint16_t length)
{
    uint16_t crc = INIT;
    uint16_t i, j;

    for (i = 0; i < length; i++) {
        crc ^= (uint16_t)data[i];
        for (j = 0; j < 8; j++) {
            if (crc & 0x0001) {
                crc = (crc >> 1) ^ POLY;
            } else {
                crc = crc >> 1;
            }
        }
    }

    return crc;
}

int main(void)
{
    FILE *fin, *fout;
    uint8_t *data;
    uint16_t crc;
    uint32_t filesize, i;

    // 打开输入文件
    fin = fopen("input.txt", "rb");
    if (fin == NULL) {
        printf("Can't open input file.\n");
        return -1;
    }

    // 打开输出文件
    fout = fopen("output.txt", "wb");
    if (fout == NULL) {
        printf("Can't open output file.\n");
        fclose(fin);
        return -1;
    }

    // 获取输入文件大小
    fseek(fin, 0, SEEK_END);
    filesize = ftell(fin);
    fseek(fin, 0, SEEK_SET);

    // 分配内存
    data = malloc(filesize);
    if (data == NULL) {
        printf("Can't allocate memory.\n");
        fclose(fin);
        fclose(fout);
        return -1;
    }

    // 读取数据流并计算CRC-16校验码
    while (fread(data, 1, 2, fin) != 0) {
        crc = crc16(data, 2);
        fwrite(data, 1, 2, fout);
        fwrite(&crc, 1, 2, fout);
    }

    // 释放内存
    free(data);

    // 关闭文件
    fclose(fin);
    fclose(fout);

    return 0;
}

3. 程序流程图如下：

start -> open input file -> check if successful
      -> open output file -> check if successful
      -> get file size
      -> allocate memory
      -> read data stream from input file
      -> calculate CRC-16 checksum
      -> write data stream to output file
      -> write checksum to output file
      -> repeat until end of file
      -> free memory
      -> close input file
      -> close output file
      -> end

4. 0x00-0xff的CRC校验码表：

const uint16_t crc16_table[256] = {
    0x0000, 0x8005, 0x800f, 0x000a, 0x801b, 0x001e, 0x0014, 0x8011,
    0x8033, 0x0036, 0x003c, 0x8039, 0x0028, 0x802d, 0x8027, 0x0022,
    0x8063, 0x0066, 0x006c, 0x8069, 0x0078, 0x807d, 0x8077, 0x0072,
    0x0050, 0x8055, 0x805f, 0x005a, 0x804b, 0x004e, 0x0044, 0x8041,
    0x80c3, 0x00c6, 0x00cc, 0x80c9, 0x00d8, 0x80dd, 0x80d7, 0x00d2,
    0x00f0, 0x80f5, 0x80ff, 0x00fa, 0x80eb, 0x00ee, 0x00e4, 0x80e1,
    0x00a0, 0x80a5, 0x80af, 0x00aa, 0x80bb, 0x00be, 0x00b4, 0x80b1,
    0x8093, 0x0096, 0x009c, 0x8099, 0x0088, 0x808d, 0x8087, 0x0082,
    0x8183, 0x0186, 0x018c, 0x8189, 0x0198, 0x819d, 0x8197, 0x0192,
    0x01b0, 0x81b5, 0x81bf, 0x01ba, 0x81ab, 0x01ae, 0x01a4, 0x81a1,
    0x01e0, 0x81e5, 0x81ef, 0x01ea, 0x81fb, 0x01fe, 0x01f4, 0x81f1,
    0x81d3, 0x01d6, 0x01dc, 0x81d9, 0x01c8, 0x81cd, 0x81c7, 0x01c2,
    0x0140, 0x8145, 0x814f, 0x014a, 0x815b, 0x015e, 0x0154, 0x8151,
    0x8173, 0x0176, 0x017c, 0x8179, 0x0168, 0x816d, 0x8167, 0x0162,
    0x8123, 0x0126, 0x012c, 0x8129, 0x0138, 0x813d, 0x8137, 0x0132,
    0x0110, 0x8115, 0x811f, 0x011a, 0x810b, 0x010e, 0x0104, 0x8101,
    0x8303, 0x0306, 0x030c, 0x8309, 0x0318, 0x831d, 0x8317, 0x0312,
    0x0330, 0x8335, 0x833f, 0x033a, 0x832b, 0x032e, 0x0324, 0x8321,
    0x0360, 0x8365, 0x836f, 0x036a, 0x837b, 0x037e, 0x0374, 0x8371,
    0x8353, 0x0356, 0x035c, 0x8359, 0x0348, 0x834d, 0x8347, 0x0342,
    0x03c0, 0x83c5, 0x83cf, 0x03ca, 0x83db, 0x03de, 0x03d4, 0x83d1,
    0x83f3, 0x03f6, 0x03fc, 0x83f9, 0x03e8, 0x83ed, 0x83e7, 0x03e2,
    0x83a3, 0x03a6, 0x03ac, 0x83a9, 0x03b8, 0x83bd, 0x83b7, 0x03b2,
    0x0390, 0x8395, 0x839f, 0x039a, 0x838b, 0x038e, 0x0384, 0x8381,
    0x0280, 0x8285, 0x828f, 0x028a, 0x829b, 0x029e, 0x0294, 0x8291,
    0x82b3, 0x02b6, 0x02bc, 0x82b9, 0x02a8, 0x82ad, 0x82a7, 0x02a2,
    0x82e3, 0x02e6, 0x02ec, 0x82e9, 0x02f8, 0x82fd, 0x82f7, 0x02f2,
    0x02d0, 0x82d5, 0x82df, 0x02da, 0x82cb, 0x02ce, 0x02c4, 0x82c1,
    0x8243, 0x0246, 0x024c, 0x8249, 0x0258, 0x825d, 0x8257, 0x0252,
    0x0270, 0x8275, 0x827f, 0x027a, 0x826b, 0x026e, 0x0264, 0x8261,
    0x0220, 0x8225, 0x822f, 0x022a, 0x823b, 0x023e, 0x0234, 0x8231,
    0x8213, 0x0216, 0x021c, 0x8219, 0x0208, 0x820d, 0x8207, 0x0202
};