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HAL_PX4: improved efficiency of serial writes

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use buffer at a time writes when possible, and use O_NONBLOCKING to
avoid txspace()
This commit is contained in:
Andrew Tridgell 2013-01-22 10:50:26 +11:00
parent 18cfd29f2f
commit 546ed19ffc
2 changed files with 35 additions and 14 deletions
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47
libraries/AP_HAL_PX4/UARTDriver.cpp
View File

@ -1,3 +1,5 @@
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include <AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
@ -69,8 +71,16 @@ void PX4UARTDriver::begin(uint32_t b)
void PX4UARTDriver::end() {}
void PX4UARTDriver::flush() {}
bool PX4UARTDriver::is_initialized() { return true; }
void PX4UARTDriver::set_blocking_writes(bool blocking) {
_nonblocking_writes = !blocking;
void PX4UARTDriver::set_blocking_writes(bool blocking)
{
unsigned v;
v = fcntl(_fd, F_GETFL, 0);
if (blocking) {
v &= ~O_NONBLOCK;
} else {
v |= O_NONBLOCK;
}
fcntl(_fd, F_SETFL, v);
}
bool PX4UARTDriver::tx_pending() { return false; }
@ -144,14 +154,11 @@ int16_t PX4UARTDriver::read() {
}
if (_readbuf_count == 0) {
// refill the read buffer
int16_t avail = available();
if (avail > 0) {
int n = ::read(_fd, _readbuf, _readbuf_size);
if (n > 0) {
_readbuf_count = n;
_readbuf_ofs = 0;
}
}
int n = ::read(_fd, _readbuf, _readbuf_size);
if (n > 0) {
_readbuf_count = n;
_readbuf_ofs = 0;
}
}
if (_readbuf_count == 0) {
return -1;
@ -163,14 +170,28 @@ int16_t PX4UARTDriver::read() {
}
/* PX4 implementations of Print virtual methods */
size_t PX4UARTDriver::write(uint8_t c) {
size_t PX4UARTDriver::write(uint8_t c)
{
if (!_initialised) {
return 0;
}
if (_nonblocking_writes && txspace() == 0) {
int ret = ::write(_fd, &c, 1);
if (ret == -1) {
ret = 0;
}
return ret;
}
size_t PX4UARTDriver::write(const uint8_t *buffer, size_t size)
{
if (!_initialised) {
return 0;
}
return ::write(_fd, &c, 1);
int ret = ::write(_fd, buffer, size);
if (ret == -1) {
ret = 0;
}
return ret;
}
// handle %S -> %s

2
libraries/AP_HAL_PX4/UARTDriver.h
View File

@ -32,6 +32,7 @@ public:
/* PX4 implementations of Print virtual methods */
size_t write(uint8_t c);
size_t write(const uint8_t *buffer, size_t size);
bool _initialised;
@ -42,7 +43,6 @@ public:
private:
const char *_devpath;
int _fd;
bool _nonblocking_writes;
void _vdprintf(int fd, const char *fmt, va_list ap);
// we keep a small read buffer to lower the cost of ::read() system calls