mbed library sources. Supersedes mbed-src.
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platform/mbed_poll.cpp
- Committer:
- AnnaBridge
- Date:
- 2017-06-21
- Revision:
- 167:e84263d55307
File content as of revision 167:e84263d55307:
/* 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" #include "Timer.h" #ifdef MBED_CONF_RTOS_PRESENT #include "rtos/Thread.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. */ Timer timer; if (timeout > 0) { timer.start(); } 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 && timer.read_ms() > timeout)) { break; } #ifdef MBED_CONF_RTOS_PRESENT // TODO - proper blocking // wait for condition variable, wait queue whatever here rtos::Thread::yield(); #endif } return count; } } // namespace mbed