EL4121 Embedded System / mbed-os

mbed-os

Dependents:   cobaLCDJoyMotor_Thread odometry_omni_3roda_v3 odometry_omni_3roda_v1 odometry_omni_3roda_v2 ... more

platform/mbed_poll.cpp@0:b74591d5ab33, 2017-12-11 (annotated)

Committer:
be_bryan
Date:
Mon Dec 11 17:54:04 2017 +0000
Revision:
0:b74591d5ab33
motor ++

Who changed what in which revision?

UserRevisionLine numberNew contents of line
be_bryan 0:b74591d5ab33 1 /* mbed Microcontroller Library
be_bryan 0:b74591d5ab33 2 * Copyright (c) 2017 ARM Limited
be_bryan 0:b74591d5ab33 3 *
be_bryan 0:b74591d5ab33 4 * Licensed under the Apache License, Version 2.0 (the "License");
be_bryan 0:b74591d5ab33 5 * you may not use this file except in compliance with the License.
be_bryan 0:b74591d5ab33 6 * You may obtain a copy of the License at
be_bryan 0:b74591d5ab33 7 *
be_bryan 0:b74591d5ab33 8 * http://www.apache.org/licenses/LICENSE-2.0
be_bryan 0:b74591d5ab33 9 *
be_bryan 0:b74591d5ab33 10 * Unless required by applicable law or agreed to in writing, software
be_bryan 0:b74591d5ab33 11 * distributed under the License is distributed on an "AS IS" BASIS,
be_bryan 0:b74591d5ab33 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
be_bryan 0:b74591d5ab33 13 * See the License for the specific language governing permissions and
be_bryan 0:b74591d5ab33 14 * limitations under the License.
be_bryan 0:b74591d5ab33 15 */
be_bryan 0:b74591d5ab33 16 #include "mbed_poll.h"
be_bryan 0:b74591d5ab33 17 #include "FileHandle.h"
be_bryan 0:b74591d5ab33 18 #include "Timer.h"
be_bryan 0:b74591d5ab33 19 #ifdef MBED_CONF_RTOS_PRESENT
be_bryan 0:b74591d5ab33 20 #include "rtos/Thread.h"
be_bryan 0:b74591d5ab33 21 #endif
be_bryan 0:b74591d5ab33 22
be_bryan 0:b74591d5ab33 23 namespace mbed {
be_bryan 0:b74591d5ab33 24
be_bryan 0:b74591d5ab33 25 // timeout -1 forever, or milliseconds
be_bryan 0:b74591d5ab33 26 int poll(pollfh fhs[], unsigned nfhs, int timeout)
be_bryan 0:b74591d5ab33 27 {
be_bryan 0:b74591d5ab33 28 /**
be_bryan 0:b74591d5ab33 29 * TODO Proper wake-up mechanism.
be_bryan 0:b74591d5ab33 30 * In order to correctly detect availability of read/write a FileHandle, we needed
be_bryan 0:b74591d5ab33 31 * a select or poll mechanisms. We opted for poll as POSIX defines in
be_bryan 0:b74591d5ab33 32 * http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html Currently,
be_bryan 0:b74591d5ab33 33 * mbed::poll() just spins and scans filehandles looking for any events we are
be_bryan 0:b74591d5ab33 34 * interested in. In future, his spinning behaviour will be replaced with
be_bryan 0:b74591d5ab33 35 * condition variables.
be_bryan 0:b74591d5ab33 36 */
be_bryan 0:b74591d5ab33 37 Timer timer;
be_bryan 0:b74591d5ab33 38 if (timeout > 0) {
be_bryan 0:b74591d5ab33 39 timer.start();
be_bryan 0:b74591d5ab33 40 }
be_bryan 0:b74591d5ab33 41
be_bryan 0:b74591d5ab33 42 int count = 0;
be_bryan 0:b74591d5ab33 43 for (;;) {
be_bryan 0:b74591d5ab33 44 /* Scan the file handles */
be_bryan 0:b74591d5ab33 45 for (unsigned n = 0; n < nfhs; n++) {
be_bryan 0:b74591d5ab33 46 FileHandle *fh = fhs[n].fh;
be_bryan 0:b74591d5ab33 47 short mask = fhs[n].events | POLLERR | POLLHUP | POLLNVAL;
be_bryan 0:b74591d5ab33 48 if (fh) {
be_bryan 0:b74591d5ab33 49 fhs[n].revents = fh->poll(mask) & mask;
be_bryan 0:b74591d5ab33 50 } else {
be_bryan 0:b74591d5ab33 51 fhs[n].revents = POLLNVAL;
be_bryan 0:b74591d5ab33 52 }
be_bryan 0:b74591d5ab33 53 if (fhs[n].revents) {
be_bryan 0:b74591d5ab33 54 count++;
be_bryan 0:b74591d5ab33 55 }
be_bryan 0:b74591d5ab33 56 }
be_bryan 0:b74591d5ab33 57
be_bryan 0:b74591d5ab33 58 if (count) {
be_bryan 0:b74591d5ab33 59 break;
be_bryan 0:b74591d5ab33 60 }
be_bryan 0:b74591d5ab33 61
be_bryan 0:b74591d5ab33 62 /* Nothing selected - this is where timeout handling would be needed */
be_bryan 0:b74591d5ab33 63 if (timeout == 0 || (timeout > 0 && timer.read_ms() > timeout)) {
be_bryan 0:b74591d5ab33 64 break;
be_bryan 0:b74591d5ab33 65 }
be_bryan 0:b74591d5ab33 66 #ifdef MBED_CONF_RTOS_PRESENT
be_bryan 0:b74591d5ab33 67 // TODO - proper blocking
be_bryan 0:b74591d5ab33 68 // wait for condition variable, wait queue whatever here
be_bryan 0:b74591d5ab33 69 rtos::Thread::wait(1);
be_bryan 0:b74591d5ab33 70 #endif
be_bryan 0:b74591d5ab33 71 }
be_bryan 0:b74591d5ab33 72 return count;
be_bryan 0:b74591d5ab33 73 }
be_bryan 0:b74591d5ab33 74
be_bryan 0:b74591d5ab33 75 } // namespace mbed