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Diff: platform/mbed_poll.cpp
- Revision:
- 0:38ceb79fef03
diff -r 000000000000 -r 38ceb79fef03 platform/mbed_poll.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/platform/mbed_poll.cpp Wed Nov 28 15:10:15 2018 +0000 @@ -0,0 +1,92 @@ +/* mbed Microcontroller Library + * Copyright (c) 2017 ARM Limited + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +#include "mbed_poll.h" +#include "FileHandle.h" +#if MBED_CONF_RTOS_PRESENT +#include "rtos/Kernel.h" +#include "rtos/Thread.h" +using namespace rtos; +#else +#include "drivers/Timer.h" +#include "drivers/LowPowerTimer.h" +#endif + +namespace mbed { + +// timeout -1 forever, or milliseconds +int poll(pollfh fhs[], unsigned nfhs, int timeout) +{ + /* + * TODO Proper wake-up mechanism. + * In order to correctly detect availability of read/write a FileHandle, we needed + * a select or poll mechanisms. We opted for poll as POSIX defines in + * http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html Currently, + * mbed::poll() just spins and scans filehandles looking for any events we are + * interested in. In future, his spinning behaviour will be replaced with + * condition variables. + */ +#if MBED_CONF_RTOS_PRESENT + uint64_t start_time = 0; + if (timeout > 0) { + start_time = Kernel::get_ms_count(); + } +#define TIME_ELAPSED() int64_t(Kernel::get_ms_count() - start_time) +#else +#if MBED_CONF_PLATFORM_POLL_USE_LOWPOWER_TIMER + LowPowerTimer timer; +#else + Timer timer; +#endif + if (timeout > 0) { + timer.start(); + } +#define TIME_ELAPSED() timer.read_ms() +#endif // MBED_CONF_RTOS_PRESENT + + int count = 0; + for (;;) { + /* Scan the file handles */ + for (unsigned n = 0; n < nfhs; n++) { + FileHandle *fh = fhs[n].fh; + short mask = fhs[n].events | POLLERR | POLLHUP | POLLNVAL; + if (fh) { + fhs[n].revents = fh->poll(mask) & mask; + } else { + fhs[n].revents = POLLNVAL; + } + if (fhs[n].revents) { + count++; + } + } + + if (count) { + break; + } + + /* Nothing selected - this is where timeout handling would be needed */ + if (timeout == 0 || (timeout > 0 && TIME_ELAPSED() > timeout)) { + break; + } +#ifdef MBED_CONF_RTOS_PRESENT + // TODO - proper blocking + // wait for condition variable, wait queue whatever here + rtos::Thread::wait(1); +#endif + } + return count; +} + +} // namespace mbed