MtxCircBuffer.h

00001 /* mbed USBHost Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 #ifndef MTXCIRCBUFFER_H
00018 #define MTXCIRCBUFFER_H
00019 
00020 #include "stdint.h"
00021 #include "rtos.h"
00022 
00023 //Mutex protected circular buffer
00024 template<typename T, int size>
00025 class MtxCircBuffer {
00026 public:
00027 
00028     MtxCircBuffer() {
00029         write = 0;
00030         read = 0;
00031     }
00032 
00033     bool isFull() {
00034         mtx.lock();
00035         bool r = (((write + 1) % size) == read);
00036         mtx.unlock();
00037         return r;
00038     }
00039 
00040     bool isEmpty() {
00041         mtx.lock();
00042         bool r = (read == write);
00043         mtx.unlock();
00044         return r;
00045     }
00046 
00047     void flush() {
00048         write = 0;
00049         read = 0;
00050     }
00051 
00052     void queue(T k) {
00053         mtx.lock();
00054         while (((write + 1) % size) == read) {
00055             mtx.unlock();
00056             Thread::wait(10);
00057             mtx.lock();
00058         }
00059         buf[write++] = k;
00060         write %= size;
00061         mtx.unlock();
00062     }
00063 
00064     uint16_t available() {
00065         mtx.lock();
00066         uint16_t a = (write >= read) ? (write - read) : (size - read + write);
00067         mtx.unlock();
00068         return a;
00069     }
00070 
00071     bool dequeue(T * c) {
00072         mtx.lock();
00073         bool empty = (read == write);
00074         if (!empty) {
00075             *c = buf[read++];
00076             read %= size;
00077         }
00078         mtx.unlock();
00079         return (!empty);
00080     }
00081 
00082 private:
00083     volatile uint16_t write;
00084     volatile uint16_t read;
00085     volatile T buf[size];
00086     Mutex mtx;
00087 };
00088 
00089 #endif