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juce::AbstractFifo Class Reference

#include <juce_AbstractFifo.h>

Classes

class  ScopedReadWrite
 

Public Types

using ScopedRead = ScopedReadWrite< ReadOrWrite::read >
 
using ScopedWrite = ScopedReadWrite< ReadOrWrite::write >
 

Public Member Functions

 AbstractFifo (int capacity) noexcept
 
 ~AbstractFifo ()
 
int getTotalSize () const noexcept
 
int getFreeSpace () const noexcept
 
int getNumReady () const noexcept
 
void reset () noexcept
 
void setTotalSize (int newSize) noexcept
 
void prepareToWrite (int numToWrite, int &startIndex1, int &blockSize1, int &startIndex2, int &blockSize2) const noexcept
 
void finishedWrite (int numWritten) noexcept
 
void prepareToRead (int numWanted, int &startIndex1, int &blockSize1, int &startIndex2, int &blockSize2) const noexcept
 
void finishedRead (int numRead) noexcept
 
ScopedRead read (int numToRead) noexcept
 
ScopedWrite write (int numToWrite) noexcept
 

Detailed Description

Encapsulates the logic required to implement a lock-free FIFO.

This class handles the logic needed when building a single-reader, single-writer FIFO.

It doesn't actually hold any data itself, but your FIFO class can use one of these to manage its position and status when reading or writing to it.

To use it, you can call prepareToWrite() to determine the position within your own buffer that an incoming block of data should be stored, and prepareToRead() to find out when the next outgoing block should be read from.

e.g.

struct MyFifo
{
void addToFifo (const int* someData, int numItems)
{
abstractFifo.prepareToWrite (numItems, start1, size1, start2, size2);
if (size1 > 0)
if (size2 > 0)
abstractFifo.finishedWrite (size1 + size2);
}
void readFromFifo (int* someData, int numItems)
{
abstractFifo.prepareToRead (numItems, start1, size1, start2, size2);
if (size1 > 0)
if (size2 > 0)
abstractFifo.finishedRead (size1 + size2);
}
AbstractFifo abstractFifo { 1024 };
int myBuffer[1024];
};

Definition at line 78 of file juce_AbstractFifo.h.

Member Typedef Documentation

◆ ScopedRead

Definition at line 262 of file juce_AbstractFifo.h.

◆ ScopedWrite

Definition at line 263 of file juce_AbstractFifo.h.

Constructor & Destructor Documentation

◆ AbstractFifo()

juce::AbstractFifo::AbstractFifo ( int  capacity)
noexcept

Creates a FIFO to manage a buffer with the specified capacity.

Definition at line 26 of file juce_AbstractFifo.cpp.

◆ ~AbstractFifo()

juce::AbstractFifo::~AbstractFifo ( )

Destructor

Definition at line 31 of file juce_AbstractFifo.cpp.

Member Function Documentation

◆ finishedRead()

void juce::AbstractFifo::finishedRead ( int  numRead)
noexcept

Called after reading from the FIFO, to indicate that this many items have now been consumed.

See also
prepareToRead

Definition at line 121 of file juce_AbstractFifo.cpp.

Referenced by juce::dsp::Convolution::Pimpl::readFromFifo().

◆ finishedWrite()

void juce::AbstractFifo::finishedWrite ( int  numWritten)
noexcept

Called after writing from the FIFO, to indicate that this many items have been added.

See also
prepareToWrite

Definition at line 83 of file juce_AbstractFifo.cpp.

Referenced by juce::dsp::Convolution::Pimpl::addToFifo(), and juce::dsp::Convolution::Pimpl::addToFifo().

◆ getFreeSpace()

int juce::AbstractFifo::getFreeSpace ( ) const
noexcept

Returns the number of items that can currently be added to the buffer without it overflowing.

Definition at line 34 of file juce_AbstractFifo.cpp.

◆ getNumReady()

int juce::AbstractFifo::getNumReady ( ) const
noexcept

Returns the number of items that can currently be read from the buffer.

Definition at line 36 of file juce_AbstractFifo.cpp.

Referenced by getFreeSpace(), and juce::dsp::Convolution::Pimpl::getNumRemainingEntries().

◆ getTotalSize()

int juce::AbstractFifo::getTotalSize ( ) const
noexcept

Returns the total size of the buffer being managed.

Definition at line 33 of file juce_AbstractFifo.cpp.

◆ prepareToRead()

void juce::AbstractFifo::prepareToRead ( int  numWanted,
int startIndex1,
int blockSize1,
int startIndex2,
int blockSize2 
) const
noexcept

Returns the location within the buffer from which the next block of data should be read.

Because the section of data that you want to read from the buffer may overlap the end and wrap around to the start, two blocks within your buffer are returned, and you should read from both of them.

If the number of items you ask for is greater than the amount of data available, then blockSize1 + blockSize2 may add up to a lower value than numWanted. If this happens, you may decide to keep waiting and re-trying the method until there's enough data available.

After calling this method, if you choose to read the data, you must call finishedRead() to tell the FIFO how much data you have consumed.

e.g.

void readFromFifo (int* someData, int numItems)
{
if (size1 > 0)
if (size2 > 0)
}
void prepareToRead(int numWanted, int &startIndex1, int &blockSize1, int &startIndex2, int &blockSize2) const noexcept
void finishedRead(int numRead) noexcept
Parameters
numWantedindicates how many items you'd like to add to the buffer
startIndex1on exit, this will contain the start index in your buffer at which your data should be written
blockSize1on exit, this indicates how many items can be written to the block starting at startIndex1
startIndex2on exit, this will contain the start index in your buffer at which any data that didn't fit into the first block should be written
blockSize2on exit, this indicates how many items can be written to the block starting at startIndex2
See also
finishedRead

Definition at line 95 of file juce_AbstractFifo.cpp.

Referenced by juce::dsp::Convolution::Pimpl::readFromFifo().

◆ prepareToWrite()

void juce::AbstractFifo::prepareToWrite ( int  numToWrite,
int startIndex1,
int blockSize1,
int startIndex2,
int blockSize2 
) const
noexcept

Returns the location within the buffer at which an incoming block of data should be written.

Because the section of data that you want to add to the buffer may overlap the end and wrap around to the start, two blocks within your buffer are returned, and you should copy your data into the first one, with any remaining data spilling over into the second.

If the number of items you ask for is too large to fit within the buffer's free space, then blockSize1 + blockSize2 may add up to a lower value than numToWrite. If this happens, you may decide to keep waiting and re-trying the method until there's enough space available.

After calling this method, if you choose to write your data into the blocks returned, you must call finishedWrite() to tell the FIFO how much data you actually added.

e.g.

void addToFifo (const int* someData, int numItems)
{
if (size1 > 0)
if (size2 > 0)
}
void prepareToWrite(int numToWrite, int &startIndex1, int &blockSize1, int &startIndex2, int &blockSize2) const noexcept
void finishedWrite(int numWritten) noexcept
Parameters
numToWriteindicates how many items you'd like to add to the buffer
startIndex1on exit, this will contain the start index in your buffer at which your data should be written
blockSize1on exit, this indicates how many items can be written to the block starting at startIndex1
startIndex2on exit, this will contain the start index in your buffer at which any data that didn't fit into the first block should be written
blockSize2on exit, this indicates how many items can be written to the block starting at startIndex2
See also
finishedWrite

Definition at line 57 of file juce_AbstractFifo.cpp.

Referenced by juce::dsp::Convolution::Pimpl::addToFifo(), and juce::dsp::Convolution::Pimpl::addToFifo().

◆ read()

AbstractFifo::ScopedRead juce::AbstractFifo::read ( int  numToRead)
noexcept

Replaces prepareToRead/finishedRead with a single function. This function returns an object which contains the start indices and block sizes, and also automatically finishes the read operation when it goes out of scope.

{
auto readHandle = fifo.read (4);
for (auto i = 0; i != readHandle.blockSize1; ++i)
{
// read the item at index readHandle.startIndex1 + i
}
for (auto i = 0; i != readHandle.blockSize2; ++i)
{
// read the item at index readHandle.startIndex2 + i
}
} // readHandle goes out of scope here, finishing the read operation

Definition at line 165 of file juce_AbstractFifo.cpp.

◆ reset()

void juce::AbstractFifo::reset ( )
noexcept

Clears the buffer positions, so that it appears empty.

Definition at line 43 of file juce_AbstractFifo.cpp.

◆ setTotalSize()

void juce::AbstractFifo::setTotalSize ( int  newSize)
noexcept

Changes the buffer's total size. Note that this isn't thread-safe, so don't call it if there's any danger that it might overlap with a call to any other method in this class!

Definition at line 49 of file juce_AbstractFifo.cpp.

◆ write()

AbstractFifo::ScopedWrite juce::AbstractFifo::write ( int  numToWrite)
noexcept

Replaces prepareToWrite/finishedWrite with a single function. This function returns an object which contains the start indices and block sizes, and also automatically finishes the write operation when it goes out of scope.

{
auto writeHandle = fifo.write (5);
for (auto i = 0; i != writeHandle.blockSize1; ++i)
{
// write the item at index writeHandle.startIndex1 + i
}
for (auto i = 0; i != writeHandle.blockSize2; ++i)
{
// write the item at index writeHandle.startIndex2 + i
}
} // writeHandle goes out of scope here, finishing the write operation

Definition at line 166 of file juce_AbstractFifo.cpp.


The documentation for this class was generated from the following files: