Lancaster University / mbed-src

Lancaster University's (short term!) clone of mbed-src for micro:bit. This is a copy of the github branch https://github.com/lancaster-university/mbed-classic

Fork of mbed-src by mbed official

common/FileSystemLike.cpp@641:be9b2017785a, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:52:54 2016 +0100
Revision:
641:be9b2017785a
Parent:
212:34d62c0b2af6 
Synchronized with git rev 1fb8ab4c

Author: James Devine

mbed-classic: BUGFIX for timer when using wait_ms from interrupt context



Previously if a user used wait[_ms,_us] in interrupt context the device would

hang indefinitely. This was due to incrementing overflowCount from

interrupt context only.



This meant that if a user used wait[_ms,_us] in an ISR with

the same or greater interrupt priority, it would result in an infinite

loop as the overflowCount variable would never be incremented, and

wait[_ms,_us] would never return.



This patch simply applies a better solution for the race condition

mentioned in the previous commit. It instead disables the timer1

interrupt and increments the overflowCount variable, preventing

the race condition whilst supporting wait[_ms,_us] in interrupt

context.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 13:0645d8841f51 1 /* mbed Microcontroller Library
bogdanm 13:0645d8841f51 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 13:0645d8841f51 3 *
bogdanm 13:0645d8841f51 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 13:0645d8841f51 5 * you may not use this file except in compliance with the License.
bogdanm 13:0645d8841f51 6 * You may obtain a copy of the License at
bogdanm 13:0645d8841f51 7 *
bogdanm 13:0645d8841f51 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 13:0645d8841f51 9 *
bogdanm 13:0645d8841f51 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 13:0645d8841f51 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 13:0645d8841f51 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 13:0645d8841f51 13 * See the License for the specific language governing permissions and
bogdanm 13:0645d8841f51 14 * limitations under the License.
bogdanm 13:0645d8841f51 15 */
bogdanm 13:0645d8841f51 16 #include "FileSystemLike.h"
bogdanm 13:0645d8841f51 17
bogdanm 13:0645d8841f51 18 namespace mbed {
bogdanm 13:0645d8841f51 19
bogdanm 13:0645d8841f51 20 class BaseDirHandle : public DirHandle {
bogdanm 13:0645d8841f51 21 public:
bogdanm 13:0645d8841f51 22 /*
bogdanm 13:0645d8841f51 23 We keep track of our current location as the n'th object in the
bogdanm 13:0645d8841f51 24 FileSystemLike list. Using a Base* instead would cause problems if that
bogdanm 13:0645d8841f51 25 object were to be destroyed between readdirs.
bogdanm 13:0645d8841f51 26 Using this method does mean though that destroying/creating objects can
bogdanm 13:0645d8841f51 27 give unusual results from readdir.
bogdanm 13:0645d8841f51 28 */
bogdanm 13:0645d8841f51 29 off_t n;
bogdanm 13:0645d8841f51 30 struct dirent cur_entry;
bogdanm 13:0645d8841f51 31
mbed_official 212:34d62c0b2af6 32 BaseDirHandle() : n(0), cur_entry() {
bogdanm 13:0645d8841f51 33 }
bogdanm 13:0645d8841f51 34
bogdanm 13:0645d8841f51 35 virtual int closedir() {
bogdanm 13:0645d8841f51 36 delete this;
bogdanm 13:0645d8841f51 37 return 0;
bogdanm 13:0645d8841f51 38 }
bogdanm 13:0645d8841f51 39
bogdanm 13:0645d8841f51 40 virtual struct dirent *readdir() {
bogdanm 13:0645d8841f51 41 FileBase *ptr = FileBase::get(n);
bogdanm 13:0645d8841f51 42 if (ptr == NULL) return NULL;
bogdanm 13:0645d8841f51 43
bogdanm 13:0645d8841f51 44 /* Increment n, so next readdir gets the next item */
bogdanm 13:0645d8841f51 45 n++;
bogdanm 13:0645d8841f51 46
bogdanm 13:0645d8841f51 47 /* Setup cur entry and return a pointer to it */
bogdanm 13:0645d8841f51 48 std::strncpy(cur_entry.d_name, ptr->getName(), NAME_MAX);
bogdanm 13:0645d8841f51 49 return &cur_entry;
bogdanm 13:0645d8841f51 50 }
bogdanm 13:0645d8841f51 51
bogdanm 13:0645d8841f51 52 virtual off_t telldir() {
bogdanm 13:0645d8841f51 53 return n;
bogdanm 13:0645d8841f51 54 }
bogdanm 13:0645d8841f51 55
bogdanm 13:0645d8841f51 56 virtual void seekdir(off_t offset) {
bogdanm 13:0645d8841f51 57 n = offset;
bogdanm 13:0645d8841f51 58 }
bogdanm 13:0645d8841f51 59
bogdanm 13:0645d8841f51 60 virtual void rewinddir() {
bogdanm 13:0645d8841f51 61 n = 0;
bogdanm 13:0645d8841f51 62 }
bogdanm 13:0645d8841f51 63 };
bogdanm 13:0645d8841f51 64
bogdanm 13:0645d8841f51 65 FileSystemLike::FileSystemLike(const char *name) : FileBase(name, FileSystemPathType) {
bogdanm 13:0645d8841f51 66
bogdanm 13:0645d8841f51 67 }
bogdanm 13:0645d8841f51 68
bogdanm 13:0645d8841f51 69 FileSystemLike::~FileSystemLike() {
bogdanm 13:0645d8841f51 70
bogdanm 13:0645d8841f51 71 }
bogdanm 13:0645d8841f51 72
bogdanm 13:0645d8841f51 73 DirHandle *FileSystemLike::opendir() {
bogdanm 13:0645d8841f51 74 return new BaseDirHandle();
bogdanm 13:0645d8841f51 75 }
bogdanm 13:0645d8841f51 76
bogdanm 13:0645d8841f51 77 } // namespace mbed