149 lines
4.8 KiB
C++
149 lines
4.8 KiB
C++
#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <termios.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <strings.h>
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#include <stdlib.h>
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#include <string>
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#include <stdint.h>
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#include "ubx.hh"
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#include <iostream>
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#include <string.h>
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using namespace std;
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#define BAUDRATE B921600
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#define MODEMDEVICE "/dev/ttyACM0"
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namespace {
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struct EofException{};
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}
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size_t readn2(int fd, void* buffer, size_t len)
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{
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size_t pos=0;
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ssize_t res;
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for(;;) {
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res = read(fd, (char*)buffer + pos, len - pos);
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if(res == 0)
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throw EofException();
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if(res < 0) {
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throw runtime_error("failed in readn2: "+string(strerror(errno)));
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}
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pos+=(size_t)res;
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if(pos == len)
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break;
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}
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return len;
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}
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static uint8_t getUint8(int fd)
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{
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uint8_t c;
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if(readn2(fd, &c, 1) != sizeof(c))
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throw EofException();
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return c;
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}
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static uint16_t getUint16(int fd)
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{
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uint8_t c[2];
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if(readn2(fd, &c, sizeof(c)) != sizeof(c))
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throw EofException();
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return c[0] + 256*c[1];
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}
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size_t writen2(int fd, const void *buf, size_t count)
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{
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const char *ptr = (char*)buf;
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const char *eptr = ptr + count;
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ssize_t res;
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while(ptr != eptr) {
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res = ::write(fd, ptr, eptr - ptr);
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if(res < 0) {
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throw runtime_error("failed in writen2: "+string(strerror(errno)));
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}
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else if (res == 0)
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throw EofException();
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ptr += (size_t) res;
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}
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return count;
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}
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int main(int argc, char** argv)
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{
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int fd, res;
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struct termios oldtio,newtio;
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fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY );
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if (fd <0) {perror(MODEMDEVICE); exit(-1); }
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tcgetattr(fd,&oldtio); /* save current port settings */
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bzero(&newtio, sizeof(newtio));
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newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;
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newtio.c_iflag = IGNPAR;
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newtio.c_oflag = 0;
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/* set input mode (non-canonical, no echo,...) */
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newtio.c_lflag = 0;
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newtio.c_cc[VTIME] = 0; /* inter-character timer unused */
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newtio.c_cc[VMIN] = 5; /* blocking read until 5 chars received */
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tcflush(fd, TCIFLUSH);
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tcsetattr(fd,TCSANOW,&newtio);
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usleep(500000);
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std::basic_string<uint8_t> msg = buildUbxMessage(0x06, 0x01, {0x02, 89});
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writen2(fd, msg.c_str(), msg.size());
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msg = buildUbxMessage(0x06, 0x01, {0x02, 89, 0, 0, 0, 1, 0, 0});
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writen2(fd, msg.c_str(), msg.size());
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msg = buildUbxMessage(0x06, 0x01, {0x02, 89});
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writen2(fd, msg.c_str(), msg.size());
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/* goal: isolate UBX messages, ignore everyting else.
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The challenge is that we might sometimes hit the 0xb5 0x62 marker
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in the middle of a message, which will cause us to possibly jump over valid messages */
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uint8_t marker[2]={0};
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for(;;) {
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marker[0] = marker[1];
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res = readn2(fd, marker+1, 1);
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if(res < 0)
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break;
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// cerr<<"marker now: "<< (int)marker[0]<<" " <<(int)marker[1]<<endl;
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if(marker[0]==0xb5 && marker[1]==0x62) { // bingo
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basic_string<uint8_t> msg;
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msg.append(marker, 2);
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msg.append(1, getUint8(fd)); // class
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msg.append(1, getUint8(fd)); // type
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uint16_t len = getUint16(fd);
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msg.append((uint8_t*)&len, 2);
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cerr<<"Got class "<<(int)msg[0]<<" type "<<(int)msg[1]<<", len = "<<len<<endl;
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uint8_t buffer[len+2];
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res=readn2(fd, buffer, len+2);
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msg.append(buffer, len+2); // checksum
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writen2(1, msg.c_str(),msg.size());
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marker[0]=marker[1]=0;
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}
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}
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tcsetattr(fd,TCSANOW,&oldtio);
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}
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