c++ - 我的 xmodem 接收功能的实现不起作用

Question

我想就我的代码征求意见，并向我展示你的实现模型。我在下面的代码中实现程序，并以此代码为基础。

现在，我为 xmodem 实现了接收器功能，但它不起作用。

在主函数中调用的“xmodem_receive”仅打印一次“Sending C ping ....”作为 printf 和，完成。

发送 xmodem 如下所示。

接收 Xmodem 不起作用。它在接收数据之前完成。

所以我想问

1)为什么我的 xmodem 接收功能不起作用？

2）为什么STX以“K”的形式出现，这可以通过IF语句

            if(recSTX == X_STX){
                printf("STX is %c\n", &recSTX);
            }else{
                printf("Garabage payload %c\n", &recSTX);
            }

这是我的实现功能

static int xmodem_receive(int serial_fd, char* filename, int _crc){
    int skip = 0;
    uint8_t sdCRC = 'C';
    uint8_t sdACK = X_ACK;
    uint8_t eof = X_EOF;
    uint8_t sdNAK = X_NAK;
    uint8_t recSTX; // receive SOH from chunk
    uint8_t recBlk; // receive blk from chunk
    uint8_t recNegBlk; // receive blk negative from chunk
    uint8_t recData[1024]; // receive data from chunk
    uint16_t recChksum;
    FILE *fp;
    int ret, fd;
    struct stat stat;
    // If we want to receive, We have to send NAK to Sendor.



        /* Writing as binary */
    fp = fopen(filename, "wb");
    //Send NAK still read SOH that header of one data chunks
        while(1){
            char status;
            printf("Waiting for sender ping ...");
            fflush(stdout);
            //
            do {
                    if(_crc){
                        printf("Send C ping....\n");
                        ret = write(serial_fd, &sdCRC, sizeof(sdCRC));
                    }else{
                        // send NAK before read SOH
                        printf("Send NAK ping....\n");
                        ret = write(serial_fd, &sdNAK, sizeof(sdNAK));
                    }    // after sending NAK,receiving　SOH from chunk
                    fflush(stdout);
                    ret = read(serial_fd, &recSTX, sizeof(recSTX));


                    if(recSTX == X_STX){
                        printf("STX is %c\n", &recSTX);
                    }else{
                        printf("Garabage payload %c\n", &recSTX);
                    }
                    fflush(stdout);
                    if (ret != sizeof(recSTX)) {
                            printf("Not working");
                            fflush(stdout);
                            perror("read");
                            return -errno;
                    }
            } while (recSTX != X_STX);

            //So next, receiving blk
            ret = read(serial_fd, &recBlk, sizeof(recBlk));
            printf("Block Num is %d\n", recBlk);
            fflush(stdout);
            if (ret != sizeof(recBlk)) {
                perror("read");
                return -errno;
            }
            ret = read(serial_fd, &recNegBlk, sizeof(recNegBlk));
            printf("Negative Block Num is %d\n", recNegBlk);
            fflush(stdout);
            if (ret != sizeof(recNegBlk)) {
                perror("read");
                return -errno;
            }
            ret = read(serial_fd, (void *)&recData, sizeof(recData));
            printf("Data buffer is %c\n", &recData);
            fflush(stdout);
            if (ret != sizeof(recData)) {
                perror("read");
                return -errno;
            }
            ret = read(serial_fd, &recChksum, sizeof(recChksum));
            printf("Check sum is %c", &recChksum);
            fflush(stdout);
            if (ret != sizeof(recChksum)) {
                perror("read");
                return -errno;
            }
            // data block number check
            if(recBlk == 0xff - recNegBlk){
                perror("read");
                return -errno;
            }
            // data integrity check
            if(recChksum == swap16(crc16(recData, sizeof(recData)))){
                perror("read");
                return -errno;
            }
            // check of appended "0xff" from end of data to  end of chunk in chunk
            unsigned char *ptr = recData;
            ptr += sizeof(recData);
            while(*ptr == 0xff){
                ptr--;
            }
            fwrite(recData, (ptr - recData),1,fp); // write Datas bytes from our buffer
            // set skip flag or end connect
            ret = write(serial_fd, &eof, sizeof(uint8_t));
            if (ret != sizeof(eof) || ret != sizeof(X_STX)){
                return -errno;
            }else{
                if(ret == X_STX){
                    skip = 1;
                }else if(ret == EOF){
                    printf("EOF ...");
                    ret = write(serial_fd, &sdACK, sizeof(sdACK));
                    break;
                }else{
                    return -errno;
                }
            }

        }
    printf("done.\n");
    fclose(fp);
    return 0;

}

这是完整的代码。

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

#define X_STX 0x02
#define X_ACK 0x06
#define X_NAK 0x15
#define X_EOF 0x04

#define min(a, b)       ((a) < (b) ? (a) : (b))

struct xmodem_chunk {
        uint8_t start;
        uint8_t block;
        uint8_t block_neg;
        uint8_t payload[1024];
        uint16_t crc;
} __attribute__((packed));

#define CRC_POLY 0x1021
static uint16_t crc_update(uint16_t crc_in, int incr)
{
    uint16_t xor1 = crc_in >> 15;
    uint16_t out1 = crc_in << 1;

    if(incr)
        out1++;

    if(xor1)
        out1 ^= CRC_POLY; // xor 0b1000000100001

    return out1;
}


static uint16_t crc16(const uint8_t *data, uint16_t size)
{
        uint16_t crc, i;

        for (crc = 0; size > 0; size--, data++)
                for (i = 0x80; i; i >>= 1)
                        crc = crc_update(crc, *data & i);

        for (i = 0; i < 16; i++)
                crc = crc_update(crc, 0);

        return crc;
}

static uint16_t swap16(uint16_t in)
{
        return (in >> 8) | ((in & 0xff) << 8);
}

enum {
        PROTOCOL_XMODEM,
        PROTOCOL_YMODEM,
};

static int xmodem_receive(int serial_fd, char* filename, int _crc){
    int skip = 0;
    uint8_t sdCRC = 'C';
    uint8_t sdACK = X_ACK;
    uint8_t eof = X_EOF;
    uint8_t sdNAK = X_NAK;
    uint8_t recSTX; // receive SOH from chunk
    uint8_t recBlk; // receive blk from chunk
    uint8_t recNegBlk; // receive blk negative from chunk
    uint8_t recData[1024]; // receive data from chunk
    uint16_t recChksum;
    FILE *fp;
    int ret, fd;
    struct stat stat;
    // If we want to receive, We have to send NAK to Sendor.



        /* Writing as binary */
    fp = fopen(filename, "wb");
    //Send NAK still read SOH that header of one data chunks
        while(1){
            char status;
            printf("Waiting for sender ping ...");
            fflush(stdout);
            //
            do {
                    if(_crc){
                        printf("Send C ping....\n");
                        ret = write(serial_fd, &sdCRC, sizeof(sdCRC));
                    }else{
                        // send NAK before read SOH
                        printf("Send NAK ping....\n");
                        ret = write(serial_fd, &sdNAK, sizeof(sdNAK));
                    }    // after sending NAK,receiving　SOH from chunk
                    fflush(stdout);
                    ret = read(serial_fd, &recSTX, sizeof(recSTX));


                    if(recSTX == X_STX){
                        printf("STX is %c\n", &recSTX);
                    }else{
                        printf("Garabage payload %c\n", &recSTX);
                    }
                    fflush(stdout);
                    if (ret != sizeof(recSTX)) {
                            printf("Not working");
                            fflush(stdout);
                            perror("read");
                            return -errno;
                    }
            } while (recSTX != X_STX);

            //So next, receiving blk
            ret = read(serial_fd, &recBlk, sizeof(recBlk));
            printf("Block Num is %d\n", recBlk);
            fflush(stdout);
            if (ret != sizeof(recBlk)) {
                perror("read");
                return -errno;
            }
            ret = read(serial_fd, &recNegBlk, sizeof(recNegBlk));
            printf("Negative Block Num is %d\n", recNegBlk);
            fflush(stdout);
            if (ret != sizeof(recNegBlk)) {
                perror("read");
                return -errno;
            }
            ret = read(serial_fd, (void *)&recData, sizeof(recData));
            printf("Data buffer is %c\n", &recData);
            fflush(stdout);
            if (ret != sizeof(recData)) {
                perror("read");
                return -errno;
            }
            ret = read(serial_fd, &recChksum, sizeof(recChksum));
            printf("Check sum is %c", &recChksum);
            fflush(stdout);
            if (ret != sizeof(recChksum)) {
                perror("read");
                return -errno;
            }
            // data block number check
            if(recBlk == 0xff - recNegBlk){
                perror("read");
                return -errno;
            }
            // data integrity check
            if(recChksum == swap16(crc16(recData, sizeof(recData)))){
                perror("read");
                return -errno;
            }
            // check of appended "0xff" from end of data to  end of chunk in chunk
            unsigned char *ptr = recData;
            ptr += sizeof(recData);
            while(*ptr == 0xff){
                ptr--;
            }
            fwrite(recData, (ptr - recData),1,fp); // write Datas bytes from our buffer
            // set skip flag or end connect
            ret = write(serial_fd, &eof, sizeof(uint8_t));
            if (ret != sizeof(eof) || ret != sizeof(X_STX)){
                return -errno;
            }else{
                if(ret == X_STX){
                    skip = 1;
                }else if(ret == EOF){
                    printf("EOF ...");
                    ret = write(serial_fd, &sdACK, sizeof(sdACK));
                    break;
                }else{
                    return -errno;
                }
            }

        }
    printf("done.\n");
    fclose(fp);
    return 0;

}

static int xymodem_send(int serial_fd, const char *filename, int protocol, int wait)
{
        size_t len;
        int ret, fd;
        uint8_t answer;
        struct stat stat;
        const uint8_t *buf;
        uint8_t eof = X_EOF;
        struct xmodem_chunk chunk;
        int skip_payload = 0;

        fd = open(filename, O_RDONLY);
        if (fd < 0) {
                perror("open");
                return -errno;
        }

        fstat(fd, &stat);
        len = stat.st_size;
        buf = static_cast<uint8_t*>(mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0));
        if (!buf) {
                perror("mmap");
                return -errno;
        }

        if (wait) {
                printf("Waiting for receiver ping ...");
                fflush(stdout);

                do {
                        ret = read(serial_fd, &answer, sizeof(answer));
                        if (ret != sizeof(answer)) {
                                perror("read");
                                return -errno;
                        }
                } while (answer != 'C');

                printf("done.\n");
        }

        printf("Sending %s ", filename);

        if (protocol == PROTOCOL_YMODEM) {
                strncpy((char *) chunk.payload, filename, sizeof(chunk.payload));
                chunk.block = 0;
                skip_payload = 1;
        } else {
                chunk.block = 1;
        }

        chunk.start = X_STX;

        while (len) {
                size_t z = 0;
                int next = 0;
                char status;

                if (!skip_payload) {
                        z = min(len, sizeof(chunk.payload));
                        memcpy(chunk.payload, buf, z);
                        memset(chunk.payload + z, 0xff, sizeof(chunk.payload) - z);
                } else {
                        skip_payload = 0;
                }

                chunk.crc = swap16(crc16(chunk.payload, sizeof(chunk.payload)));
                chunk.block_neg = 0xff - chunk.block;

                ret = write(serial_fd, &chunk, sizeof(chunk));
                if (ret != sizeof(chunk))
                        return -errno;

                ret = read(serial_fd, &answer, sizeof(answer));
                if (ret != sizeof(answer))
                        return -errno;
                switch (answer) {
                case X_NAK:
                        status = 'N';
                        break;
                case X_ACK:
                        status = '.';
                        next = 1;
                        break;
                default:
                        status = '?';
                        break;
                }

                printf("%c", status);
                fflush(stdout);

                if (next) {
                        chunk.block++;
                        len -= z;
                        buf += z;
                }
        }

        ret = write(serial_fd, &eof, sizeof(eof));
        if (ret != sizeof(eof))
                return -errno;

        /* send EOT again for YMODEM */
        if (protocol == PROTOCOL_YMODEM) {
                ret = write(serial_fd, &eof, sizeof(eof));
                if (ret != sizeof(eof))
                        return -errno;
        }

        printf("done.\n");

        return 0;
}

static int open_serial(const char *path, int baud)
{
        int fd;
        struct termios tty;

        fd = open(path, O_RDWR | O_SYNC);
        if (fd < 0) {
                perror("open");
                return -errno;
        }

        memset(&tty, 0, sizeof(tty));
        if (tcgetattr(fd, &tty) != 0) {
                perror("tcgetattr");
                return -errno;
        }

        cfsetospeed(&tty, baud);
        cfsetispeed(&tty, baud);

        tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8;     // 8-bit chars
        tty.c_iflag &= ~IGNBRK;                         // disable break processing
        tty.c_lflag = 0;                                // no signaling chars, no echo,
                                                        // no canonical processing
        tty.c_oflag = 0;                                // no remapping, no delays
        tty.c_cc[VMIN]  = 1;                            // read doesn't block
        tty.c_cc[VTIME] = 5;                            // 0.5 seconds read timeout

        tty.c_iflag &= ~(IXON | IXOFF | IXANY);         // shut off xon/xoff ctrl

        tty.c_cflag |= (CLOCAL | CREAD);                // ignore modem controls,
                                                        // enable reading
        tty.c_cflag &= ~(PARENB | PARODD);              // shut off parity
        tty.c_cflag &= ~CSTOPB;
        tty.c_cflag &= ~CRTSCTS;

        if (tcsetattr(fd, TCSANOW, &tty) != 0) {
                perror("tcsetattr");
                return -errno;
        }

        return fd;
}

static void dump_serial(int serial_fd)
{
        char in;

        for (;;) {
                read(serial_fd, &in, sizeof(in));
                printf("%c", in);
                fflush(stdout);
        }
}

#ifdef TEST_XMODEM_RECEIVE

#endif // TEST_XMODEM_RECEIVE

int main(int argc, char **argv)
{
        int a, ret, serial_fd;

        printf("STX: %c\n", X_STX);

        printf("ACK: %c\n", X_ACK);

        printf("NAK: %c\n", X_NAK);

        printf("EOF: %c\n", X_EOF);

        fflush(stdout);

        serial_fd = open_serial("/dev/ttyUSB0", 115200);
        if (serial_fd < 0)
                return -errno;


        if(std::string(argv[2]) == "0" || std::string(argv[2]) == "0"){
            ret = xymodem_send(serial_fd, argv[1], PROTOCOL_XMODEM, 1);
            if (ret < 0)
                return ret;
        }

        if(std::string(argv[2]) == "1"){
            ret = xmodem_receive(serial_fd, argv[1], 1);
            if (ret < 0)
                return ret;
        }


        return 0;
}

感谢您浏览我的问题。