我想在下面的代码中发送和接收文件。 但是功能有问题，＆＃34; xmodem_receive＆＃34;。
＆＃34; xmodem_send＆＃34;功能是发送＆＃34; xmodem_chunk＆＃34;通过＆＃34; tty / AMA0＆＃34;并且接收数据是＆＃34; ret = saferead（fd，＆amp; chunk，sizeof（chunk））＆＃34; in＆＃34; xmodem_receive＆＃34; 但这条线上没有读数据！相反，这行停止了我的代码。 有人教我至少需要运行这段代码吗？
这是代码（略）。
#define X_STX 0x02
#define X_EOT 0x04
#define X_ACK 0x06
#define X_NAK 0x15
#define min(a, b) ((a) < (b) ? (a) : (b))
#define DEBUG 0
struct xmodem_chunk {
uint8_t start;
uint8_t blk;
uint8_t blk_neg;
uint8_t payload[1024];
uint16_t crc;
} __attribute__((packed));
#define CRC_POLY 0x1021
int saferead(int fd, const void *p, size_t want){
int ret;
int ret_sum = 0;
errno = 0;
while (want){
ret = read(fd, (uint8_t*)p, want);
if(ret == 0)
return -1; /* EOF */
if(ret <= 0){
if(errno != EINTR && errno != EAGAIN ) {
return -1;
}
errno = 0;
continue;
}
want -= ret;
p = (uint8_t*) p + ret;
ret_sum += ret;
}
return ret_sum;
}
static int xmodem_send(int serial_fd, const char *filename)
{
int ret, fd;
uint8_t eof = X_EOT;
struct xmodem_chunk chunk;
fd = open(filename, O_RDONLY);
if(fd < 0){
perror("open");
return -errno;
}
fstat(fd, &stat);
len = stat.st_size;
buf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
if(!buf){
perror("mmap");
return -errno;
}
printf("Sending %s \n", filename);
chunk.start = X_STX;
while (len){
size_t z = 0;
int next = 0;
char status;
z = min(len, sizeof(chunk.payload));
memcpy(chunk.payload, buf, z);
memset(chunk.payload + z, 0xff, sizeof(chunk.payload) - z);
chunk.crc = swap16(crc16(chunk.payload, sizeof(chunk.payload)));
chunk.blk_neg = 0xff - chunk.blk;
int i;
for(i = 0; i < 3; i++){
ret = safewrite(serial_fd, &chunk, sizeof(chunk));
if(ret != sizeof(chunk)){
return -errno;
}
}
if(next){
chunk.blk++;
len -= z;
buf += z;
}
}
ret = safewrite(serial_fd, &eof, sizeof(eof));
if(ret != sizeof(eof))
return -errno;
return 0;
}
static xmodem_receive(int serial_fd, char* filename){
size_t len;
int ret, fd;
size_t retry;
struct xmodem_chunk chunk;
struct stat stat;
FILE *fp;
uint8_t eof = X_EOT;
int eof_count=0;
retry = 3;
fp = fopen(filename, "ab+");
while(1){
int garbage_count=0;
int correct_count=0;
uint8_t chunk_payload[1024];
uint8_t garbage_payload[3][1024];
uint16_t garbage_crc[3];
size_t z = 0;
while(retry){
int next = 0;
ret = saferead(fd, &chunk, sizeof(chunk)); <--This line is the problem.
z = sizeof(chunk.payload);
if(chunk.start != X_STX){
printf("error STX\n");
return 0; // error
}
printf("retry part\n");
if(chunk.crc != swap16(crc16(chunk.payload, sizeof(chunk.payload)))){
if(garbage_count > 1){
int i;
for(i=0; i < garbage_count; i++){
if(chunk.crc == swap16(crc16(garbage_payload[i], sizeof(chunk.payload)))){
correct_count++;
memcpy(chunk_payload, garbage_payload[i], len);
}
}
if(correct_count < 1){
memcpy(garbage_payload[garbage_count], &chunk.payload, len);
garbage_count++;
}
printf("garbage#1\n");
}else{
memcpy(garbage_payload[0], &chunk.payload, len);
garbage_crc[0] = chunk.crc;
garbage_count++;
printf("garbage#2\n");
}
}else{
printf("correct\n");
correct_count++;
memcpy(chunk_payload , &chunk.payload, len);
}
}
safewrite(fd, &chunk_payload, z);
}
close(fd);
return 0;
}
int main(int argc, char **argv){
int a, ret, serial_fd;
serial_fd = open_serial("/dev/ttyUSB0", 115200);
// serial_fd = open_serial("/dev/ttyAMA0", 115200);
ret = xmodem_receive(serial_fd, "sample.jpg");
// ret = xmodem_send(serial_fd, "sample.jpg");
}
这是完整的代码（很抱歉让你久等）
`
#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>
#define X_STX 0x02
#define X_EOT 0x04
#define X_ACK 0x06
#define X_NAK 0x15
#define min(a, b) ((a) < (b) ? (a) : (b))
#define DEBUG 0
struct xmodem_chunk {
uint8_t start;
uint8_t blk;
uint8_t blk_neg;
uint8_t payload[1024];
uint16_t crc;
} __attribute__((packed));
#define CRC_POLY 0x1021
/* 'Safe' write */
int safewrite(int fd, const void *p, size_t want){
int ret;
int ret_sum = 0;
errno = 0;
while(want){
ret = write(fd, (uint8_t *)p,want);
if(ret <= 0) {
if (errno != EINTR && errno != EAGAIN){
return -1;
}
errno = 0;
continue;
}
want -= ret;
p = (uint8_t*) p + ret;
ret_sum += ret;
}
return ret_sum;
}
int saferead(int fd, const void *p, size_t want){
int ret;
int ret_sum = 0;
errno = 0;
while (want){
ret = read(fd, (uint8_t*)p, want);
if(ret == 0)
return -1; /* EOF */
if(ret <= 0){
if(errno != EINTR && errno != EAGAIN ) {
return -1;
}
errno = 0;
continue;
}
want -= ret;
p = (uint8_t*) p + ret;
ret_sum += ret;
}
return ret_sum;
}
static uint16_t crc_update(uint16_t crc_in, int incr)
{
uint16_t xor = crc_in >> 15;
uint16_t out = crc_in << 1;
if(incr)
out++;
if(xor)
out ^= CRC_POLY; // xor 0b1000000100001
return out;
}
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 xymodem_send(int serial_fd, const char *filename)
{
size_t len;
int ret, fd;
uint8_t answer;
struct stat stat;
const uint8_t *buf;
uint8_t eof = X_EOT;
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 = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
if(!buf){
perror("mmap");
return -errno;
}
if(DEBUG) {
printf("Wainting 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("dome.\n");
}
printf("Sending %s ", filename);
/*
if(protocol == PROTOCOL_YMODEM) {
strncpy ((char*) chunk.payload, filename, sizeof(chunk.payload));
chunk.blk = 0;
skip_payload = 1;
}else {
chunk.blk = 1;
}
*/
chunk.start = X_STX;
while (len){
size_t z = 0;
int next = 0;
char status;
z = min(len, sizeof(chunk.payload));
memcpy(chunk.payload, buf, z);
memset(chunk.payload + z, 0xff, sizeof(chunk.payload) - z); //
chunk.crc = swap16(crc16(chunk.payload, sizeof(chunk.payload)));
chunk.blk_neg = 0xff - chunk.blk;
int i;
for(i = 0; i < 3; i++){
ret = safewrite(serial_fd, &chunk, sizeof(chunk));
if(ret != sizeof(chunk)){
return -errno;
}
}
if(next){
chunk.blk++;
len -= z;
buf += z;
}
}
ret = safewrite(serial_fd, &eof, sizeof(eof));
if(ret != sizeof(eof))
return -errno;
ret = safewrite(serial_fd, &eof, sizeof(eof));
if (ret != sizeof(eof))
return -errno;
ret = safewrite(serial_fd, &eof, sizeof(eof));
if (ret != sizeof(eof))
return -errno;
printf("done.\n");
return 0;
}
static xmodem_receive(int serial_fd, char* filename){
size_t len;
int ret, fd;
size_t retry;
uint8_t expected_blkno;
size_t nrecv;
uint16_t crch, crcl;
size_t datalen;
struct xmodem_chunk chunk;
struct stat stat;
int file_size=0;
int c;
FILE *fp;
char* exet;
uint8_t send_start;
uint8_t eof = X_EOT;
int eof_count=0;
retry = 3;
fp = fopen(filename, "ab+");
while(1){
int v_stx_count=0;
int inv_stx_count=0;
int garbage_blk_count=0;
int correct_blk_count=0;
int garbage_count=0;
int correct_count=0;
uint8_t chunk_payload[1024];
uint8_t garbage_payload[3][1024];
uint16_t garbage_crc[3];
int val_payload_crc_pr = 0;
int val_payload_crc_cr = 0;
int val_payload_crc_nx = 0;
int pr_val_crc=0;
int nx_val_crc=0;
int val_crc=0;
size_t z = 0;
while(retry){
int next = 0;
ret = saferead(fd, &chunk, 1);
printf("read chunk");
z = sizeof(chunk.payload);
if(chunk.start != X_STX){
printf("error STX\n");
return 0; // error
}
printf("retry part\n");
if(chunk.crc != swap16(crc16(chunk.payload, sizeof(chunk.payload)))){
if(garbage_count > 1){
int i;
for(i=0; i < garbage_count; i++){
if(chunk.crc == swap16(crc16(garbage_payload[i], sizeof(chunk.payload)))){
correct_count++;
memcpy(chunk_payload, garbage_payload[i], len);
}
}
if(correct_count < 1){
memcpy(garbage_payload[garbage_count], &chunk.payload, len);
garbage_count++;
}
printf("garbage#1\n");
}else{
// ごみの登録
memcpy(garbage_payload[0], &chunk.payload, len);
garbage_crc[0] = chunk.crc;
garbage_count++;
printf("garbage#2\n");
}
}else{
printf("correct\n");
correct_count++;
memcpy(chunk_payload , &chunk.payload, len);
}
}
safewrite(fd, &chunk_payload, z);
}
close(fd);
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
tty.c_iflag &= ~IGNBRK; // disable break processing
tty.c_lflag = 0; // nosignaling 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 controlsm
tty.c_cflag &= ~(PARENB | PARODD); // ignore modem controls,
// enable reading
tty.c_cflag &= ~(PARENB | PARODD); // shut off party
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);
}
}
int main(int argc, char **argv){
int a, ret, serial_fd;
serial_fd = open_serial("/dev/ttyUSB0", 115200);
ret = xmodem_receive(serial_fd, "sample.jpg");
// dump_serial(serial_fd);
}
`
答案 0 :(得分：2)
您的程序从不接收任何数据，因为它从不尝试使用串行端口执行I / O.
xmodem_receive（）从不使用其参数serial_fd。
static xmodem_receive(int serial_fd, char* filename){
相反，此例程使用未初始化的变量fd作为调用 saferead（）和 safewrite（）的参数。
int ret, fd;
...
ret = saferead(fd, &chunk, 1);
...
safewrite(fd, &chunk_payload, z);
要复合此错误，您不必费心检查这些调用的返回值，因此使用未初始化的变量（即无效的文件描述符）导致的任何错误都会被静默丢弃。