1
0
mirror of https://github.com/hsoft/collapseos.git synced 2024-12-26 06:38:06 +11:00
collapseos/tools/common.c
Virgil Dupras a19c814b0d tools: improve reliability of ttyopen()
Previously, communications with my RC2014 would always be rocky and
fail most of the time. By sending an CR at init, things go much
smoother.
2020-09-17 10:25:08 -04:00

160 lines
3.9 KiB
C

#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#define BREATHE usleep(2000)
//#define DEBUG(...) fprintf(stderr, __VA_ARGS__)
#define DEBUG(...)
void mread(int fd, char *s, int count)
{
while (count) {
while (read(fd, s, 1) == 0) {
BREATHE;
}
s++;
count--;
}
}
// Make sure that nothing is waiting in the pipeline
static void mempty(int fd)
{
char c;
while (read(fd, &c, 1) == 1) {
DEBUG("Emptying %d\n", c);
BREATHE;
}
}
int mexpect(int fd, unsigned char ec)
{
unsigned char c;
mread(fd, &c, 1);
if (c != ec) {
fprintf(stderr, "Expected %x but got %x\n", ec, c);
return 0;
}
return 1;
}
void readprompt(int fd)
{
mexpect(fd, ' ');
mexpect(fd, 'o');
mexpect(fd, 'k');
mexpect(fd, '\r');
mexpect(fd, '\n');
}
void sendcmd(int fd, char *cmd)
{
DEBUG("Sending %s\n", cmd);
char junk[2];
while (*cmd) {
DEBUG("W: %d\n", *cmd);
write(fd, cmd, 1);
BREATHE;
read(fd, &junk, 1);
DEBUG("R: %d\n", *junk);
cmd++;
// The other side is sometimes much slower than us and if we don't let
// it breathe, it can choke.
BREATHE;
}
write(fd, "\r", 1);
mexpect(fd, '\r');
mexpect(fd, '\n');
BREATHE;
}
// Send a cmd and also read the " ok" prompt
void sendcmdp(int fd, char *cmd)
{
sendcmd(fd, cmd);
readprompt(fd);
}
// from https://stackoverflow.com/a/6947758
// discussion from https://stackoverflow.com/a/26006680 is interesting,
// but we don't want POSIX compliance.
int set_interface_attribs(int fd, int speed, int parity)
{
struct termios tty;
if (tcgetattr (fd, &tty) != 0) {
fprintf(stderr, "error %d from tcgetattr", errno);
return -1;
}
if (speed) {
cfsetospeed (&tty, speed);
cfsetispeed (&tty, speed);
}
tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8; // 8-bit chars
// disable IGNBRK for mismatched speed tests; otherwise receive break
// as \000 chars
tty.c_iflag &= ~IGNBRK; // disable break processing
tty.c_iflag &= ~ICRNL; // disable CR->NL mapping
tty.c_lflag = 0; // no signaling chars, no echo,
// no canonical processing
tty.c_oflag = 0; // no remapping, no delays
tty.c_cc[VMIN] = 0; // 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 |= parity;
tty.c_cflag &= ~CSTOPB;
tty.c_cflag &= ~CRTSCTS;
if (tcsetattr (fd, TCSANOW, &tty) != 0) {
fprintf(stderr, "error %d from tcsetattr", errno);
return -1;
}
return 0;
}
void set_blocking(int fd, int should_block)
{
struct termios tty;
memset(&tty, 0, sizeof tty);
if (tcgetattr (fd, &tty) != 0) {
fprintf(stderr, "error %d from tggetattr", errno);
return;
}
tty.c_cc[VMIN] = should_block ? 1 : 0;
tty.c_cc[VTIME] = 1; // 0.1 seconds read timeout
if (tcsetattr (fd, TCSANOW, &tty) != 0) {
fprintf(stderr, "error %d setting term attributes", errno);
}
}
int ttyopen(char *devname)
{
int fd = 0;
if (strcmp(devname, "-") != 0) {
fd = open(devname, O_RDWR|O_NOCTTY|O_SYNC);
}
set_interface_attribs(fd, 0, 0);
set_blocking(fd, 0);
mempty(fd);
// Communication with device is much more reliable if we
// begin by sending, asynchronously, a CR to make sure we
// empty any pending stuff on all sides.
write(fd, "\r", 1);
mempty(fd);
set_blocking(fd, 1);
return fd;
}