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Fixing a reading buffer bug and expanding the example

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This commit is contained in:
William Woodall 2012-02-04 21:56:10 -06:00
parent 0eab7f1f38
commit 6853f8c05d
2 changed files with 110 additions and 42 deletions
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79
examples/serial_example.cc
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@ -1,3 +1,21 @@
/***
* This example expects the serial port has a loopback on it.
*
* Alternatively, you could use an Arduino:
*
* <pre>
* setup() {
* Serial.begin(<insert your baudrate here>);
* }
*
* loop() {
* if (Serial.available()) {
* Serial.write(Serial.read());
* }
* }
* </pre>
*/
#include <string>
#include <iostream>
#include <cstdio>
@ -40,14 +58,15 @@ int run(int argc, char **argv)
sscanf(argv[2], "%lu", &baud);
// port, baudrate, timeout in milliseconds
serial::Serial serial(port, baud, 1000);
serial::Serial my_serial(port, baud, 1000);
cout << "Is the serial port open?";
if(serial.isOpen())
if(my_serial.isOpen())
cout << " Yes." << endl;
else
cout << " No." << endl;
// Get the Test string
int count = 0;
string test_string;
if (argc == 4) {
@ -55,17 +74,65 @@ int run(int argc, char **argv)
} else {
test_string = "Testing.";
}
while (true) {
size_t bytes_wrote = serial.write(test_string);
string result = serial.read(test_string.length());
// Test the timeout, there should be 1 second between prints
cout << "Timeout == 1000ms, asking for 1 more byte than written." << endl;
while (count < 10) {
size_t bytes_wrote = my_serial.write(test_string);
string result = my_serial.read(test_string.length()+1);
cout << "Iteration: " << count << ", Bytes written: ";
cout << bytes_wrote << ", Bytes read: ";
cout << result.length() << ", String read: " << result << endl;
count += 1;
}
// Test the timeout at 250ms
my_serial.setTimeout(250);
count = 0;
cout << "Timeout == 250ms, asking for 1 more byte than written." << endl;
while (count < 10) {
size_t bytes_wrote = my_serial.write(test_string);
string result = my_serial.read(test_string.length()+1);
cout << "Iteration: " << count << ", Bytes written: ";
cout << bytes_wrote << ", Bytes read: ";
cout << result.length() << ", String read: " << result << endl;
count += 1;
}
// Test the timeout at 250ms, but asking exactly for what was written
count = 0;
cout << "Timeout == 250ms, asking for exactly what was written." << endl;
while (count < 10) {
size_t bytes_wrote = my_serial.write(test_string);
string result = my_serial.read(test_string.length());
cout << "Iteration: " << count << ", Bytes written: ";
cout << bytes_wrote << ", Bytes read: ";
cout << result.length() << ", String read: " << result << endl;
count += 1;
}
// Test the timeout at 250ms, but asking for 1 less than what was written
count = 0;
cout << "Timeout == 250ms, asking for 1 less than was written." << endl;
while (count < 10) {
size_t bytes_wrote = my_serial.write(test_string);
string result = my_serial.read(test_string.length()-1);
cout << "Iteration: " << count << ", Bytes written: ";
cout << bytes_wrote << ", Bytes read: ";
cout << result.length() << ", String read: " << result << endl;
count += 1;
my_sleep(10);
}
return 0;

3
src/impl/unix.cc
View File

@ -454,7 +454,8 @@ Serial::SerialImpl::read (unsigned char* buf, size_t size)
if (FD_ISSET (fd_, &readfds)) {
// This should be non-blocking returning only what is avaialble now
// Then returning so that select can block again.
ssize_t bytes_read_now = ::read (fd_, buf, size-bytes_read);
ssize_t bytes_read_now =
::read (fd_, buf+bytes_read, size-bytes_read);
// read should always return some data as select reported it was
// ready to read when we get to this point.
if (bytes_read_now < 1)