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Opencv 3.1 project on GR-PEACH board

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platform/mbed_poll.cpp@170:54ff26da7eb6, 2017-07-04 (annotated)

Committer:
thedo
Date:
Tue Jul 04 06:23:13 2017 +0000
Revision:
170:54ff26da7eb6
Parent:
166:3a9487d57a5c 
project opencv 3.1 on GR PEACH board, no use SD card.

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thedo 166:3a9487d57a5c 1 /* mbed Microcontroller Library
thedo 166:3a9487d57a5c 2 * Copyright (c) 2017 ARM Limited
thedo 166:3a9487d57a5c 3 *
thedo 166:3a9487d57a5c 4 * Licensed under the Apache License, Version 2.0 (the "License");
thedo 166:3a9487d57a5c 5 * you may not use this file except in compliance with the License.
thedo 166:3a9487d57a5c 6 * You may obtain a copy of the License at
thedo 166:3a9487d57a5c 7 *
thedo 166:3a9487d57a5c 8 * http://www.apache.org/licenses/LICENSE-2.0
thedo 166:3a9487d57a5c 9 *
thedo 166:3a9487d57a5c 10 * Unless required by applicable law or agreed to in writing, software
thedo 166:3a9487d57a5c 11 * distributed under the License is distributed on an "AS IS" BASIS,
thedo 166:3a9487d57a5c 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
thedo 166:3a9487d57a5c 13 * See the License for the specific language governing permissions and
thedo 166:3a9487d57a5c 14 * limitations under the License.
thedo 166:3a9487d57a5c 15 */
thedo 166:3a9487d57a5c 16 #include "mbed_poll.h"
thedo 166:3a9487d57a5c 17 #include "FileHandle.h"
thedo 166:3a9487d57a5c 18 #include "Timer.h"
thedo 166:3a9487d57a5c 19 #ifdef MBED_CONF_RTOS_PRESENT
thedo 166:3a9487d57a5c 20 #include "rtos/Thread.h"
thedo 166:3a9487d57a5c 21 #endif
thedo 166:3a9487d57a5c 22
thedo 166:3a9487d57a5c 23 namespace mbed {
thedo 166:3a9487d57a5c 24
thedo 166:3a9487d57a5c 25 // timeout -1 forever, or milliseconds
thedo 166:3a9487d57a5c 26 int poll(pollfh fhs[], unsigned nfhs, int timeout)
thedo 166:3a9487d57a5c 27 {
thedo 166:3a9487d57a5c 28 /**
thedo 166:3a9487d57a5c 29 * TODO Proper wake-up mechanism.
thedo 166:3a9487d57a5c 30 * In order to correctly detect availability of read/write a FileHandle, we needed
thedo 166:3a9487d57a5c 31 * a select or poll mechanisms. We opted for poll as POSIX defines in
thedo 166:3a9487d57a5c 32 * http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html Currently,
thedo 166:3a9487d57a5c 33 * mbed::poll() just spins and scans filehandles looking for any events we are
thedo 166:3a9487d57a5c 34 * interested in. In future, his spinning behaviour will be replaced with
thedo 166:3a9487d57a5c 35 * condition variables.
thedo 166:3a9487d57a5c 36 */
thedo 166:3a9487d57a5c 37 Timer timer;
thedo 166:3a9487d57a5c 38 if (timeout > 0) {
thedo 166:3a9487d57a5c 39 timer.start();
thedo 166:3a9487d57a5c 40 }
thedo 166:3a9487d57a5c 41
thedo 166:3a9487d57a5c 42 int count = 0;
thedo 166:3a9487d57a5c 43 for (;;) {
thedo 166:3a9487d57a5c 44 /* Scan the file handles */
thedo 166:3a9487d57a5c 45 for (unsigned n = 0; n < nfhs; n++) {
thedo 166:3a9487d57a5c 46 FileHandle *fh = fhs[n].fh;
thedo 166:3a9487d57a5c 47 short mask = fhs[n].events | POLLERR | POLLHUP | POLLNVAL;
thedo 166:3a9487d57a5c 48 if (fh) {
thedo 166:3a9487d57a5c 49 fhs[n].revents = fh->poll(mask) & mask;
thedo 166:3a9487d57a5c 50 } else {
thedo 166:3a9487d57a5c 51 fhs[n].revents = POLLNVAL;
thedo 166:3a9487d57a5c 52 }
thedo 166:3a9487d57a5c 53 if (fhs[n].revents) {
thedo 166:3a9487d57a5c 54 count++;
thedo 166:3a9487d57a5c 55 }
thedo 166:3a9487d57a5c 56 }
thedo 166:3a9487d57a5c 57
thedo 166:3a9487d57a5c 58 if (count) {
thedo 166:3a9487d57a5c 59 break;
thedo 166:3a9487d57a5c 60 }
thedo 166:3a9487d57a5c 61
thedo 166:3a9487d57a5c 62 /* Nothing selected - this is where timeout handling would be needed */
thedo 166:3a9487d57a5c 63 if (timeout == 0 || (timeout > 0 && timer.read_ms() > timeout)) {
thedo 166:3a9487d57a5c 64 break;
thedo 166:3a9487d57a5c 65 }
thedo 166:3a9487d57a5c 66 #ifdef MBED_CONF_RTOS_PRESENT
thedo 166:3a9487d57a5c 67 // TODO - proper blocking
thedo 166:3a9487d57a5c 68 // wait for condition variable, wait queue whatever here
thedo 166:3a9487d57a5c 69 rtos::Thread::yield();
thedo 166:3a9487d57a5c 70 #endif
thedo 166:3a9487d57a5c 71 }
thedo 166:3a9487d57a5c 72 return count;
thedo 166:3a9487d57a5c 73 }
thedo 166:3a9487d57a5c 74
thedo 166:3a9487d57a5c 75 } // namespace mbed
thedo 166:3a9487d57a5c 76