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Replace sp_sync_read_timeout() with serialport_read_nonblock()

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It seems useful to have a generic and platform-independent method to
read and write to a serial port without blocking. This is the read part.

It stores the current blocking properties before disabling blocking and
restores them after reading. The timeout is implemented as previously
by retrying every millisecond until the timeout is reached or enough
characters are available.

Corresponding to flashrom svn r1661.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
This commit is contained in:
Stefan Tauner
2013-04-01 00:45:38 +00:00
parent da5b17c0a2
commit 00e1608501
3 changed files with 75 additions and 24 deletions
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70
serial.c
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@ -361,3 +361,73 @@ int serialport_read(unsigned char *buf, unsigned int readcnt)
return 0;
}
/* Tries up to timeout ms to read readcnt characters and places them into the array starting at c. Returns
* 0 on success, positive values on temporary errors (e.g. timeouts) and negative ones on permanent errors.
* If really_read is not NULL, this function sets its contents to the number of bytes read successfully. */
int serialport_read_nonblock(unsigned char *c, unsigned int readcnt, unsigned int timeout, unsigned int *really_read)
{
int ret = 1;
/* disable blocked i/o and declare platform-specific variables */
#ifdef _WIN32
DWORD rv;
COMMTIMEOUTS oldTimeout;
COMMTIMEOUTS newTimeout = {
.ReadIntervalTimeout = MAXDWORD,
.ReadTotalTimeoutMultiplier = 0,
.ReadTotalTimeoutConstant = 0,
.WriteTotalTimeoutMultiplier = 0,
.WriteTotalTimeoutConstant = 0
};
if(!GetCommTimeouts(sp_fd, &oldTimeout)) {
msg_perr_strerror("Could not get serial port timeout settings: ");
return -1;
}
if(!SetCommTimeouts(sp_fd, &newTimeout)) {
#else
ssize_t rv;
const int flags = fcntl(sp_fd, F_GETFL);
if (fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK) != 0) {
#endif
msg_perr_strerror("Could not set serial port timeout settings %s");
return -1;
}
int i;
int rd_bytes = 0;
for (i = 0; i < timeout; i++) {
msg_pspew("readcnt %d rd_bytes %d\n", readcnt, rd_bytes);
#ifdef _WIN32
ReadFile(sp_fd, c + rd_bytes, readcnt - rd_bytes, &rv, NULL);
msg_pspew("read %lu bytes\n", rv);
#else
rv = read(sp_fd, c + rd_bytes, readcnt - rd_bytes);
msg_pspew("read %zd bytes\n", rv);
#endif
if ((rv == -1) && (errno != EAGAIN)) {
msg_perr_strerror("Serial port read error: ");
ret = -1;
break;
}
if (rv > 0)
rd_bytes += rv;
if (rd_bytes == readcnt) {
ret = 0;
break;
}
internal_delay(1000); /* 1ms units */
}
if (really_read != NULL)
*really_read = rd_bytes;
/* restore original blocking behavior */
#ifdef _WIN32
if (!SetCommTimeouts(sp_fd, &oldTimeout)) {
#else
if (fcntl(sp_fd, F_SETFL, flags) != 0) {
#endif
msg_perr_strerror("Could not restore serial port timeout settings: %s\n");
ret = -1;
}
return ret;
}