mbed official / mbed-dev

mbed library sources. Supersedes mbed-src.

Dependents:   Nucleo_Hello_Encoder BLE_iBeaconScan AM1805_DEMO DISCO-F429ZI_ExportTemplate1 ... more

platform/mbed_poll.cpp@167:e84263d55307, 2017-06-21 (annotated)

Committer:
AnnaBridge
Date:
Wed Jun 21 17:46:44 2017 +0100
Revision:
167:e84263d55307
Child:
176:447f873cad2f
This updates the lib to the mbed lib v 145

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 167:e84263d55307 1 /* mbed Microcontroller Library
AnnaBridge 167:e84263d55307 2 * Copyright (c) 2017 ARM Limited
AnnaBridge 167:e84263d55307 3 *
AnnaBridge 167:e84263d55307 4 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 167:e84263d55307 5 * you may not use this file except in compliance with the License.
AnnaBridge 167:e84263d55307 6 * You may obtain a copy of the License at
AnnaBridge 167:e84263d55307 7 *
AnnaBridge 167:e84263d55307 8 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 167:e84263d55307 9 *
AnnaBridge 167:e84263d55307 10 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 167:e84263d55307 11 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 167:e84263d55307 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 167:e84263d55307 13 * See the License for the specific language governing permissions and
AnnaBridge 167:e84263d55307 14 * limitations under the License.
AnnaBridge 167:e84263d55307 15 */
AnnaBridge 167:e84263d55307 16 #include "mbed_poll.h"
AnnaBridge 167:e84263d55307 17 #include "FileHandle.h"
AnnaBridge 167:e84263d55307 18 #include "Timer.h"
AnnaBridge 167:e84263d55307 19 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 167:e84263d55307 20 #include "rtos/Thread.h"
AnnaBridge 167:e84263d55307 21 #endif
AnnaBridge 167:e84263d55307 22
AnnaBridge 167:e84263d55307 23 namespace mbed {
AnnaBridge 167:e84263d55307 24
AnnaBridge 167:e84263d55307 25 // timeout -1 forever, or milliseconds
AnnaBridge 167:e84263d55307 26 int poll(pollfh fhs[], unsigned nfhs, int timeout)
AnnaBridge 167:e84263d55307 27 {
AnnaBridge 167:e84263d55307 28 /**
AnnaBridge 167:e84263d55307 29 * TODO Proper wake-up mechanism.
AnnaBridge 167:e84263d55307 30 * In order to correctly detect availability of read/write a FileHandle, we needed
AnnaBridge 167:e84263d55307 31 * a select or poll mechanisms. We opted for poll as POSIX defines in
AnnaBridge 167:e84263d55307 32 * http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html Currently,
AnnaBridge 167:e84263d55307 33 * mbed::poll() just spins and scans filehandles looking for any events we are
AnnaBridge 167:e84263d55307 34 * interested in. In future, his spinning behaviour will be replaced with
AnnaBridge 167:e84263d55307 35 * condition variables.
AnnaBridge 167:e84263d55307 36 */
AnnaBridge 167:e84263d55307 37 Timer timer;
AnnaBridge 167:e84263d55307 38 if (timeout > 0) {
AnnaBridge 167:e84263d55307 39 timer.start();
AnnaBridge 167:e84263d55307 40 }
AnnaBridge 167:e84263d55307 41
AnnaBridge 167:e84263d55307 42 int count = 0;
AnnaBridge 167:e84263d55307 43 for (;;) {
AnnaBridge 167:e84263d55307 44 /* Scan the file handles */
AnnaBridge 167:e84263d55307 45 for (unsigned n = 0; n < nfhs; n++) {
AnnaBridge 167:e84263d55307 46 FileHandle *fh = fhs[n].fh;
AnnaBridge 167:e84263d55307 47 short mask = fhs[n].events | POLLERR | POLLHUP | POLLNVAL;
AnnaBridge 167:e84263d55307 48 if (fh) {
AnnaBridge 167:e84263d55307 49 fhs[n].revents = fh->poll(mask) & mask;
AnnaBridge 167:e84263d55307 50 } else {
AnnaBridge 167:e84263d55307 51 fhs[n].revents = POLLNVAL;
AnnaBridge 167:e84263d55307 52 }
AnnaBridge 167:e84263d55307 53 if (fhs[n].revents) {
AnnaBridge 167:e84263d55307 54 count++;
AnnaBridge 167:e84263d55307 55 }
AnnaBridge 167:e84263d55307 56 }
AnnaBridge 167:e84263d55307 57
AnnaBridge 167:e84263d55307 58 if (count) {
AnnaBridge 167:e84263d55307 59 break;
AnnaBridge 167:e84263d55307 60 }
AnnaBridge 167:e84263d55307 61
AnnaBridge 167:e84263d55307 62 /* Nothing selected - this is where timeout handling would be needed */
AnnaBridge 167:e84263d55307 63 if (timeout == 0 || (timeout > 0 && timer.read_ms() > timeout)) {
AnnaBridge 167:e84263d55307 64 break;
AnnaBridge 167:e84263d55307 65 }
AnnaBridge 167:e84263d55307 66 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 167:e84263d55307 67 // TODO - proper blocking
AnnaBridge 167:e84263d55307 68 // wait for condition variable, wait queue whatever here
AnnaBridge 167:e84263d55307 69 rtos::Thread::yield();
AnnaBridge 167:e84263d55307 70 #endif
AnnaBridge 167:e84263d55307 71 }
AnnaBridge 167:e84263d55307 72 return count;
AnnaBridge 167:e84263d55307 73 }
AnnaBridge 167:e84263d55307 74
AnnaBridge 167:e84263d55307 75 } // namespace mbed