ringbuffer/ringbuffer.cpp at master · w-ensink/ringbuffer · GitHub

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#include<iostream>
#include"ringbuffer.h"
#include<unistd.h>
#include<string.h>


// Size is specified as #items, not bytes.

template<typename FloatType>
RingBuffer<FloatType>::RingBuffer(const uint64 size, const std::string& name) :
size(size),
 buffer(new FloatType[size]),
 tail(0),
 head(0),
 name(name),
 blockingPush(false),
 blockingPop(false)
{

}


template<typename FloatType>
RingBuffer<FloatType>::~RingBuffer()
{
delete[] buffer;
}


template<typename FloatType>
auto RingBuffer<FloatType>::numItemsAvailableForWrite() const -> uint64
{
// signed space between head and tail index
constlong pointerSpace = head.load() - tail.load();

// NB: > 0 so NOT including 0
return pointerSpace > 0 ? pointerSpace : pointerSpace + size;
}


template<typename FloatType>
auto RingBuffer<FloatType>::numItemsAvailableForRead() const -> uint64
{
// signed space between tail and head index
constlong pointerSpace = tail.load() - head.load();

// NB: >= 0 so including 0
return pointerSpace >= 0 ? pointerSpace : pointerSpace + size;
}


template<typename FloatType>
auto RingBuffer<FloatType>::pushMayBlock(bool block) -> void
{
 blockingPush = block;
}


template<typename FloatType>
auto RingBuffer<FloatType>::popMayBlock(bool block) -> void
{
 blockingPop = block;
}


template<typename FloatType>
auto RingBuffer<FloatType>::setBlockingNap(const uint64 newBlockingNap) -> void
{
 blockingNap = newBlockingNap;
}


// Try to write as many items as possible and return the number actually written

template<typename FloatType>
auto RingBuffer<FloatType>::push(FloatType* data, const uint64 numSamples) -> uint64
{
auto space = size;

if(blockingPush)
while((space = numItemsAvailableForWrite()) < numSamples)
usleep(static_cast<useconds_t>(blockingNap));

if(space == 0) return0;

constauto numToWrite = numSamples <= space ? numSamples : space;

constauto currentTail = tail.load();

// wrap if needed
if(currentTail + numToWrite <= size)
 {
memcpy(buffer + currentTail, data, numToWrite * itemSize);
 }
else
 {
constauto firstChunk = size - currentTail;
memcpy(buffer + currentTail, data, firstChunk * itemSize);
memcpy(buffer, data + firstChunk, (numToWrite - firstChunk) * itemSize);
 }

 tail.store((currentTail + numToWrite) % size);

return numToWrite;
}


// Try to read as many items as possible and return the number actually read

template<typename FloatType>
auto RingBuffer<FloatType>::pop(FloatType* data, const uint64 numSamples) -> uint64
{
auto space = size;

if(blockingPop)
while((space = numItemsAvailableForRead()) < numSamples)
usleep(static_cast<useconds_t>(blockingNap));

if(space == 0) return0;

constauto numToRead = numSamples <= space ? numSamples : space;

constauto currentHead = head.load();

//wrap if needed
if(currentHead + numToRead <= size)
 {
memcpy(data, buffer + currentHead, numToRead * itemSize);
 }
else
 {
constauto firstChunk = size - currentHead;
memcpy(data, buffer + currentHead, firstChunk * itemSize);
memcpy(data + firstChunk, buffer, (numToRead - firstChunk) * itemSize);
 }

 head.store((currentHead + numToRead) % size);

return numToRead;
}


template<typename FloatType>
auto RingBuffer<FloatType>::isLockFree() const -> bool
{
return (tail.is_lock_free() && head.is_lock_free());
}

//three available types as of now...
template classRingBuffer<float>;
template classRingBuffer<double>;
template classRingBuffer<longdouble>;