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

// To compile on Ubuntu or Mac OS X with xcode:
//   gcc -O3 -Wall -o serial_listen serial_listen.c

const char *begin_string="10 second speed test begins";
const char *end_string="done!\r\n";
#define END_LEN 7

int main(int argc, char **argv)
{
	char buf[16384];
	int port;
	long n, sum=0, dotcount=0;
	struct termios settings;

	if (argc < 2) {
		fprintf(stderr, "Usage:   serial_listen <port>\n");
		#if #system(linux)
		fprintf(stderr, "Example: serial_listen /dev/ttyACM0\n");
		#else
		fprintf(stderr, "Example: serial_listen /dev/cu.usbmodem12341\n");
		#endif
		return 1;
	}

	// Open the serial port
	port = open(argv[1], O_RDONLY);
	if (port < 0) {
		fprintf(stderr, "Unable to open %s\n", argv[1]);
		return 1;
	}

	// Configure the port
	tcgetattr(port, &settings);
	cfmakeraw(&settings);
	tcsetattr(port, TCSANOW, &settings);

	// Read data until we get a see the end string or get an error
	printf("Reading from %s\n", argv[1]);
	while (1) {
		n = read(port, buf, sizeof(buf));
		if (n < 1) {
			fprintf(stderr, "error reading from %s\n", argv[1]);
			break;
		}
		if (n < 50 && memcmp(buf, begin_string, strlen(begin_string)) == 0) {
			printf("read: %ld (begin string)\n", n);
			continue;
		}
		if (n < sizeof(buf) && n >= END_LEN &&
		  memcmp(buf + n - END_LEN, end_string, END_LEN) == 0) {
			printf("(end string)\n");
			sum += n - END_LEN;
			break;
		}
		sum += n;
		//printf("read: %ld, total: %ld\n", n, sum);
		dotcount += n;
		if (dotcount > sizeof(buf)) {
			dotcount -= sizeof(buf);
			printf(".");
			fflush(stdout);
		}
	}

	close(port);
	printf("Total bytes read: %ld\n", sum);
	printf("Speed %.2f kbytes/sec\n", sum / 10000.0);
	return 0;
}