tmk_core/tool/mbed/mbed-sdk/libraries/USBHost/USBHostSerial/MtxCircBuffer.h

   1 /* mbed USBHost Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef MTXCIRCBUFFER_H
  18 #define MTXCIRCBUFFER_H
  19
  20 #include "stdint.h"
  21 #include "rtos.h"
  22
  23 //Mutex protected circular buffer
  24 template<typename T, int size>
  25 class MtxCircBuffer {
  26 public:
  27
  28     MtxCircBuffer() {
  29         write = 0;
  30         read = 0;
  31     }
  32
  33     bool isFull() {
  34         mtx.lock();
  35         bool r = (((write + 1) % size) == read);
  36         mtx.unlock();
  37         return r;
  38     }
  39
  40     bool isEmpty() {
  41         mtx.lock();
  42         bool r = (read == write);
  43         mtx.unlock();
  44         return r;
  45     }
  46
  47     void flush() {
  48         write = 0;
  49         read = 0;
  50     }
  51
  52     void queue(T k) {
  53         mtx.lock();
  54         while (((write + 1) % size) == read) {
  55             mtx.unlock();
  56             Thread::wait(10);
  57             mtx.lock();
  58         }
  59         buf[write++] = k;
  60         write %= size;
  61         mtx.unlock();
  62     }
  63
  64     uint16_t available() {
  65         mtx.lock();
  66         uint16_t a = (write >= read) ? (write - read) : (size - read + write);
  67         mtx.unlock();
  68         return a;
  69     }
  70
  71     bool dequeue(T * c) {
  72         mtx.lock();
  73         bool empty = (read == write);
  74         if (!empty) {
  75             *c = buf[read++];
  76             read %= size;
  77         }
  78         mtx.unlock();
  79         return (!empty);
  80     }
  81
  82 private:
  83     volatile uint16_t write;
  84     volatile uint16_t read;
  85     volatile T buf[size];
  86     Mutex mtx;
  87 };
  88
  89 #endif