帮我找一个C语言的HDLC代码

下面是一个简单的C语言HDLC协议的实现，其中使用了CRC-16校验：

#include <stdio.h>
#include <string.h>

#define FLAG 0x7E
#define ESC 0x7D
#define XON 0x11
#define XOFF 0x13

#define CRC16_POLY 0x8005

typedef unsigned char BYTE;
typedef unsigned short WORD;

WORD crc16(BYTE *data, int len)
{
    WORD crc = 0xFFFF;
    int i, j;
    for (i = 0; i < len; i++) {
        crc ^= (WORD)data[i] << 8;
        for (j = 0; j < 8; j++) {
            if (crc & 0x8000)
                crc = (crc << 1) ^ CRC16_POLY;
            else
                crc <<= 1;
        }
    }
    return crc;
}

void hdlc_encode(BYTE *input, int input_len, BYTE *output, int *output_len)
{
    int i, j, k;
    WORD crc = crc16(input, input_len);
    output[0] = FLAG;
    for (i = 0, j = 1; i < input_len; i++) {
        if (input[i] == FLAG || input[i] == ESC) {
            output[j++] = ESC;
            output[j++] = input[i] ^ 0x20;
        } else {
            output[j++] = input[i];
        }
    }
    for (k = 0; k < 2; k++) {
        if (crc & 0x8000)
            output[j++] = ESC;
        output[j++] = (BYTE)(crc >> 8) ^ 0x20;
        crc <<= 8;
    }
    output[j++] = FLAG;
    *output_len = j;
}

void hdlc_decode(BYTE *input, int input_len, BYTE *output, int *output_len)
{
    int i, j;
    WORD crc = 0xFFFF;
    for (i = 1, j = 0; i < input_len - 1; i++) {
        if (input[i] == ESC) {
            output[j++] = input[++i] ^ 0x20;
        } else {
            output[j++] = input[i];
        }
    }
    *output_len = j - 2;
    crc = crc16(output, *output_len);
    if ((BYTE)(crc >> 8) == input[input_len - 3] ^ 0x20 && (BYTE)crc == input[input_len - 2] ^ 0x20) {
        *output_len -= 2;
    } else {
        *output_len = -1;
    }
}

int main()
{
    BYTE input[] = {0x01, 0x02, 0x03, 0x04};
    BYTE output[1024];
    int output_len;
    hdlc_encode(input, sizeof(input), output, &output_len);
    printf("Encoded: ");
    for (int i = 0; i < output_len; i++) {
        printf("%02X ", output[i]);
    }
    printf("\n");
    BYTE decoded[1024];
    int decoded_len;
    hdlc_decode(output, output_len, decoded, &decoded_len);
    printf("Decoded: ");
    for (int i = 0; i < decoded_len; i++) {
        printf("%02X ", decoded[i]);
    }
    printf("\n");
    return 0;