File content as of revision 79:d28244984385:

/* Copyright (c) 2010-2011 mbed.org, MIT License
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or
* substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef CIRCBUFFER_H
#define CIRCBUFFER_H

template <class T, int Size>
class CircBuffer {
public:
    CircBuffer():write(0), read(0){}
    bool isFull() {
        return ((write + 1) % size == read);
    };

    bool isEmpty() {
        return (read == write);
    };

    void queue(T k) {
        if (isFull()) {
            read++;
            read %= size;
        }
        buf[write++] = k;
        write %= size;
    }

    uint16_t available() {
        return (write >= read) ? write - read : size - read + write;
    };

    bool dequeue(T * c) {
        bool empty = isEmpty();
        if (!empty) {
            *c = buf[read++];
            read %= size;
        }
        return(!empty);
    };

    void flush()
    {
        write = 0;
        read = 0;
    }

    // Queue a block of data of blockSize items
    void queue(const T *block, uint16_t blockSize)
    {
        if (blockSize >= size)
        {
            // Block is too big to fit in buffer, take the last size-1 items
            block = &block[blockSize - (size-1)];
            blockSize = size-1;
        }

        if (write + blockSize > size)
        {
            // Need to wrap around
            std::memcpy(&buf[write], block, sizeof(T)*(size-write));
            std::memcpy(buf, &block[size-write], sizeof(T)*(blockSize - (size-write)));
        }
        else
        {
            std::memcpy(&buf[write], block, sizeof(T)*blockSize);
        }

        // Update write position
        uint16_t wasFree = available() - size - 1;
        write = write + blockSize;
        write %= size;
        if (wasFree < blockSize)
        {
            // Update read position as well
            read = write + 1;
            read %= size;
        }
    }

    // Dequeue a block of data of at most blockSize items, writing them into block
    // Returns the number of items dequeued
    uint16_t dequeue(T *block, uint16_t blockSize)
    {
        if (isEmpty())
        {
            return 0;
        }

        uint16_t isAvailable = available();
        if (isAvailable < blockSize)
        {
            // Only return what we have
            blockSize = isAvailable;
        }

        if (read + blockSize > size)
        {
            // Need to wrap around
            std::memcpy(block, &buf[read], sizeof(T)*(size-read));
            std::memcpy(&block[size-read], buf, sizeof(T)*(blockSize - (size-read)));
        }
        else
        {
            std::memcpy(block, &buf[read], sizeof(T)*blockSize);
        }

        // Update read position
        read = read + blockSize;
        read %= size;

        return blockSize;
    }

private:
    volatile uint16_t write;
    volatile uint16_t read;
    static const int size = Size+1;  //a modern optimizer should be able to remove this so it uses no ram.
    T buf[Size+1];
};

#endif