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Fill out waitByteTimes, integrate it into read as discussed in ticket #37

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This commit is contained in:
Mike Purvis 2013-11-06 22:27:17 -05:00
parent 28025034bd
commit d74c74bf15
2 changed files with 24 additions and 9 deletions
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3
include/serial/impl/unix.h
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@ -199,8 +199,9 @@ private:
bool xonxoff_;
bool rtscts_;
Timeout timeout_; // Timeout for read operations
Timeout timeout_; // Timeout for read operations
unsigned long baudrate_; // Baudrate
uint32_t byte_time_ns_; // Nanoseconds to transmit/receive a single byte
parity_t parity_; // Parity
bytesize_t bytesize_; // Size of the bytes

30
src/impl/unix.cc
View File

@ -420,6 +420,16 @@ Serial::SerialImpl::reconfigurePort ()
// activate settings
::tcsetattr (fd_, TCSANOW, &options);
// Update byte_time_ based on the new settings.
uint32_t bit_time_ns = 1e9 / baudrate_;
byte_time_ns_ = bit_time_ns * (1 + bytesize_ + parity_ + stopbits_);
// Compensate for the stopbits_one_point_five enum being equal to int 3,
// and not 1.5.
if (stopbits_ == stopbits_one_point_five) {
byte_time_ns_ += ((1.5 - stopbits_one_point_five) * bit_time_ns);
}
}
void
@ -457,11 +467,10 @@ Serial::SerialImpl::available ()
bool
Serial::SerialImpl::waitReadable (uint32_t timeout)
{
// Setup a select call to block for serial data or a timeout
fd_set readfds;
FD_ZERO (&readfds);
FD_SET (fd_, &readfds);
// Call select to block for serial data or a timeout
timespec timeout_ts (timespec_from_ms (timeout));
int r = pselect (fd_ + 1, &readfds, NULL, NULL, &timeout_ts, NULL);
@ -473,18 +482,15 @@ Serial::SerialImpl::waitReadable (uint32_t timeout)
// Otherwise there was some error
THROW (IOException, errno);
}
// Timeout occurred
if (r == 0) {
return false;
}
// This shouldn't happen, if r > 0 our fd has to be in the list!
if (!FD_ISSET (fd_, &readfds)) {
THROW (IOException, "select reports ready to read, but our fd isn't"
" in the list, this shouldn't happen!");
}
// Data available to read.
return true;
}
@ -492,7 +498,8 @@ Serial::SerialImpl::waitReadable (uint32_t timeout)
void
Serial::SerialImpl::waitByteTimes (size_t count)
{
timespec wait_time = { 0, byte_time_ns_ * count };
pselect (0, NULL, NULL, NULL, &wait_time, NULL);
}
size_t
@ -523,14 +530,21 @@ Serial::SerialImpl::read (uint8_t *buf, size_t size)
// Timed out
break;
}
// Timeout for the next select is whichever is less of the remaining
// total read timeout and the inter-byte timeout.
uint32_t timeout = std::min(static_cast<uint32_t> (timeout_remaining_ms),
timeout_.inter_byte_timeout);
// Wait for the device to be readable, and then attempt to read.
if (waitReadable(timeout)) {
// If it's a fixed-length multi-byte read, insert a wait here so that
// we can attempt to grab the whole thing in a single IO call. Skip
// this wait if a non-max inter_byte_timeout is specified.
if (size > 1 && timeout_.inter_byte_timeout == Timeout::max()) {
size_t bytes_available = available();
if (bytes_available + bytes_read < size) {
waitByteTimes(size - (bytes_available + bytes_read));
}
}
// This should be non-blocking returning only what is available now
// Then returning so that select can block again.
ssize_t bytes_read_now =