PES4 / Mbed OS Queue_02

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mbed-os/platform/mbed_poll.cpp@0:6bf0743ece18, 2020-03-28 (annotated)

Committer:
demayer
Date:
Sat Mar 28 15:28:19 2020 +0000
Revision:
0:6bf0743ece18
IMU Thread with an event-queue running parallel to handle tasks like a 5 times blinking LED. Button with interrupt detected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
demayer 0:6bf0743ece18 1 /* mbed Microcontroller Library
demayer 0:6bf0743ece18 2 * Copyright (c) 2017 ARM Limited
demayer 0:6bf0743ece18 3 *
demayer 0:6bf0743ece18 4 * Licensed under the Apache License, Version 2.0 (the "License");
demayer 0:6bf0743ece18 5 * you may not use this file except in compliance with the License.
demayer 0:6bf0743ece18 6 * You may obtain a copy of the License at
demayer 0:6bf0743ece18 7 *
demayer 0:6bf0743ece18 8 * http://www.apache.org/licenses/LICENSE-2.0
demayer 0:6bf0743ece18 9 *
demayer 0:6bf0743ece18 10 * Unless required by applicable law or agreed to in writing, software
demayer 0:6bf0743ece18 11 * distributed under the License is distributed on an "AS IS" BASIS,
demayer 0:6bf0743ece18 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
demayer 0:6bf0743ece18 13 * See the License for the specific language governing permissions and
demayer 0:6bf0743ece18 14 * limitations under the License.
demayer 0:6bf0743ece18 15 */
demayer 0:6bf0743ece18 16 #include "mbed_poll.h"
demayer 0:6bf0743ece18 17 #include "FileHandle.h"
demayer 0:6bf0743ece18 18 #include "Timer.h"
demayer 0:6bf0743ece18 19 #ifdef MBED_CONF_RTOS_PRESENT
demayer 0:6bf0743ece18 20 #include "rtos/Thread.h"
demayer 0:6bf0743ece18 21 #endif
demayer 0:6bf0743ece18 22
demayer 0:6bf0743ece18 23 namespace mbed {
demayer 0:6bf0743ece18 24
demayer 0:6bf0743ece18 25 // timeout -1 forever, or milliseconds
demayer 0:6bf0743ece18 26 int poll(pollfh fhs[], unsigned nfhs, int timeout)
demayer 0:6bf0743ece18 27 {
demayer 0:6bf0743ece18 28 /**
demayer 0:6bf0743ece18 29 * TODO Proper wake-up mechanism.
demayer 0:6bf0743ece18 30 * In order to correctly detect availability of read/write a FileHandle, we needed
demayer 0:6bf0743ece18 31 * a select or poll mechanisms. We opted for poll as POSIX defines in
demayer 0:6bf0743ece18 32 * http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html Currently,
demayer 0:6bf0743ece18 33 * mbed::poll() just spins and scans filehandles looking for any events we are
demayer 0:6bf0743ece18 34 * interested in. In future, his spinning behaviour will be replaced with
demayer 0:6bf0743ece18 35 * condition variables.
demayer 0:6bf0743ece18 36 */
demayer 0:6bf0743ece18 37 Timer timer;
demayer 0:6bf0743ece18 38 if (timeout > 0) {
demayer 0:6bf0743ece18 39 timer.start();
demayer 0:6bf0743ece18 40 }
demayer 0:6bf0743ece18 41
demayer 0:6bf0743ece18 42 int count = 0;
demayer 0:6bf0743ece18 43 for (;;) {
demayer 0:6bf0743ece18 44 /* Scan the file handles */
demayer 0:6bf0743ece18 45 for (unsigned n = 0; n < nfhs; n++) {
demayer 0:6bf0743ece18 46 FileHandle *fh = fhs[n].fh;
demayer 0:6bf0743ece18 47 short mask = fhs[n].events | POLLERR | POLLHUP | POLLNVAL;
demayer 0:6bf0743ece18 48 if (fh) {
demayer 0:6bf0743ece18 49 fhs[n].revents = fh->poll(mask) & mask;
demayer 0:6bf0743ece18 50 } else {
demayer 0:6bf0743ece18 51 fhs[n].revents = POLLNVAL;
demayer 0:6bf0743ece18 52 }
demayer 0:6bf0743ece18 53 if (fhs[n].revents) {
demayer 0:6bf0743ece18 54 count++;
demayer 0:6bf0743ece18 55 }
demayer 0:6bf0743ece18 56 }
demayer 0:6bf0743ece18 57
demayer 0:6bf0743ece18 58 if (count) {
demayer 0:6bf0743ece18 59 break;
demayer 0:6bf0743ece18 60 }
demayer 0:6bf0743ece18 61
demayer 0:6bf0743ece18 62 /* Nothing selected - this is where timeout handling would be needed */
demayer 0:6bf0743ece18 63 if (timeout == 0 || (timeout > 0 && timer.read_ms() > timeout)) {
demayer 0:6bf0743ece18 64 break;
demayer 0:6bf0743ece18 65 }
demayer 0:6bf0743ece18 66 #ifdef MBED_CONF_RTOS_PRESENT
demayer 0:6bf0743ece18 67 // TODO - proper blocking
demayer 0:6bf0743ece18 68 // wait for condition variable, wait queue whatever here
demayer 0:6bf0743ece18 69 rtos::Thread::wait(1);
demayer 0:6bf0743ece18 70 #endif
demayer 0:6bf0743ece18 71 }
demayer 0:6bf0743ece18 72 return count;
demayer 0:6bf0743ece18 73 }
demayer 0:6bf0743ece18 74
demayer 0:6bf0743ece18 75 } // namespace mbed