Marco Zecchini / Mbed OS Example_RTOS

Rtos API example

mbed-os/platform/mbed_poll.cpp@0:9fca2b23d0ba, 2019-02-23 (annotated)

Committer:
marcozecchini
Date:
Sat Feb 23 12:13:36 2019 +0000
Revision:
0:9fca2b23d0ba
final commit

Who changed what in which revision?

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marcozecchini 0:9fca2b23d0ba 1 /* mbed Microcontroller Library
marcozecchini 0:9fca2b23d0ba 2 * Copyright (c) 2017 ARM Limited
marcozecchini 0:9fca2b23d0ba 3 *
marcozecchini 0:9fca2b23d0ba 4 * Licensed under the Apache License, Version 2.0 (the "License");
marcozecchini 0:9fca2b23d0ba 5 * you may not use this file except in compliance with the License.
marcozecchini 0:9fca2b23d0ba 6 * You may obtain a copy of the License at
marcozecchini 0:9fca2b23d0ba 7 *
marcozecchini 0:9fca2b23d0ba 8 * http://www.apache.org/licenses/LICENSE-2.0
marcozecchini 0:9fca2b23d0ba 9 *
marcozecchini 0:9fca2b23d0ba 10 * Unless required by applicable law or agreed to in writing, software
marcozecchini 0:9fca2b23d0ba 11 * distributed under the License is distributed on an "AS IS" BASIS,
marcozecchini 0:9fca2b23d0ba 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
marcozecchini 0:9fca2b23d0ba 13 * See the License for the specific language governing permissions and
marcozecchini 0:9fca2b23d0ba 14 * limitations under the License.
marcozecchini 0:9fca2b23d0ba 15 */
marcozecchini 0:9fca2b23d0ba 16 #include "mbed_poll.h"
marcozecchini 0:9fca2b23d0ba 17 #include "FileHandle.h"
marcozecchini 0:9fca2b23d0ba 18 #include "Timer.h"
marcozecchini 0:9fca2b23d0ba 19 #ifdef MBED_CONF_RTOS_PRESENT
marcozecchini 0:9fca2b23d0ba 20 #include "rtos/Thread.h"
marcozecchini 0:9fca2b23d0ba 21 #endif
marcozecchini 0:9fca2b23d0ba 22
marcozecchini 0:9fca2b23d0ba 23 namespace mbed {
marcozecchini 0:9fca2b23d0ba 24
marcozecchini 0:9fca2b23d0ba 25 // timeout -1 forever, or milliseconds
marcozecchini 0:9fca2b23d0ba 26 int poll(pollfh fhs[], unsigned nfhs, int timeout)
marcozecchini 0:9fca2b23d0ba 27 {
marcozecchini 0:9fca2b23d0ba 28 /**
marcozecchini 0:9fca2b23d0ba 29 * TODO Proper wake-up mechanism.
marcozecchini 0:9fca2b23d0ba 30 * In order to correctly detect availability of read/write a FileHandle, we needed
marcozecchini 0:9fca2b23d0ba 31 * a select or poll mechanisms. We opted for poll as POSIX defines in
marcozecchini 0:9fca2b23d0ba 32 * http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html Currently,
marcozecchini 0:9fca2b23d0ba 33 * mbed::poll() just spins and scans filehandles looking for any events we are
marcozecchini 0:9fca2b23d0ba 34 * interested in. In future, his spinning behaviour will be replaced with
marcozecchini 0:9fca2b23d0ba 35 * condition variables.
marcozecchini 0:9fca2b23d0ba 36 */
marcozecchini 0:9fca2b23d0ba 37 Timer timer;
marcozecchini 0:9fca2b23d0ba 38 if (timeout > 0) {
marcozecchini 0:9fca2b23d0ba 39 timer.start();
marcozecchini 0:9fca2b23d0ba 40 }
marcozecchini 0:9fca2b23d0ba 41
marcozecchini 0:9fca2b23d0ba 42 int count = 0;
marcozecchini 0:9fca2b23d0ba 43 for (;;) {
marcozecchini 0:9fca2b23d0ba 44 /* Scan the file handles */
marcozecchini 0:9fca2b23d0ba 45 for (unsigned n = 0; n < nfhs; n++) {
marcozecchini 0:9fca2b23d0ba 46 FileHandle *fh = fhs[n].fh;
marcozecchini 0:9fca2b23d0ba 47 short mask = fhs[n].events | POLLERR | POLLHUP | POLLNVAL;
marcozecchini 0:9fca2b23d0ba 48 if (fh) {
marcozecchini 0:9fca2b23d0ba 49 fhs[n].revents = fh->poll(mask) & mask;
marcozecchini 0:9fca2b23d0ba 50 } else {
marcozecchini 0:9fca2b23d0ba 51 fhs[n].revents = POLLNVAL;
marcozecchini 0:9fca2b23d0ba 52 }
marcozecchini 0:9fca2b23d0ba 53 if (fhs[n].revents) {
marcozecchini 0:9fca2b23d0ba 54 count++;
marcozecchini 0:9fca2b23d0ba 55 }
marcozecchini 0:9fca2b23d0ba 56 }
marcozecchini 0:9fca2b23d0ba 57
marcozecchini 0:9fca2b23d0ba 58 if (count) {
marcozecchini 0:9fca2b23d0ba 59 break;
marcozecchini 0:9fca2b23d0ba 60 }
marcozecchini 0:9fca2b23d0ba 61
marcozecchini 0:9fca2b23d0ba 62 /* Nothing selected - this is where timeout handling would be needed */
marcozecchini 0:9fca2b23d0ba 63 if (timeout == 0 || (timeout > 0 && timer.read_ms() > timeout)) {
marcozecchini 0:9fca2b23d0ba 64 break;
marcozecchini 0:9fca2b23d0ba 65 }
marcozecchini 0:9fca2b23d0ba 66 #ifdef MBED_CONF_RTOS_PRESENT
marcozecchini 0:9fca2b23d0ba 67 // TODO - proper blocking
marcozecchini 0:9fca2b23d0ba 68 // wait for condition variable, wait queue whatever here
marcozecchini 0:9fca2b23d0ba 69 rtos::Thread::wait(1);
marcozecchini 0:9fca2b23d0ba 70 #endif
marcozecchini 0:9fca2b23d0ba 71 }
marcozecchini 0:9fca2b23d0ba 72 return count;
marcozecchini 0:9fca2b23d0ba 73 }
marcozecchini 0:9fca2b23d0ba 74
marcozecchini 0:9fca2b23d0ba 75 } // namespace mbed