PublicUtility/CARingBuffer.cpp

/*
     File: CARingBuffer.cpp 
 Abstract:  CARingBuffer.h  
  Version: 1.2.2 
  
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*/
#include "CARingBuffer.h"
#include "CABitOperations.h"
#include "CAAutoDisposer.h"
#include "CAAtomic.h"
 
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <libkern/OSAtomic.h>
 
CARingBuffer::CARingBuffer() :
    mBuffers(NULL), mNumberChannels(0), mCapacityFrames(0), mCapacityBytes(0)
{
 
}
 
CARingBuffer::~CARingBuffer()
{
    Deallocate();
}
 
 
void    CARingBuffer::Allocate(int nChannels, UInt32 bytesPerFrame, UInt32 capacityFrames)
{
    Deallocate();
    
    capacityFrames = NextPowerOfTwo(capacityFrames);
    
    mNumberChannels = nChannels;
    mBytesPerFrame = bytesPerFrame;
    mCapacityFrames = capacityFrames;
    mCapacityFramesMask = capacityFrames - 1;
    mCapacityBytes = bytesPerFrame * capacityFrames;
 
    // put everything in one memory allocation, first the pointers, then the deinterleaved channels
    UInt32 allocSize = (mCapacityBytes + sizeof(Byte *)) * nChannels;
    Byte *p = (Byte *)CA_malloc(allocSize);
    memset(p, 0, allocSize);
    mBuffers = (Byte **)p;
    p += nChannels * sizeof(Byte *);
    for (int i = 0; i < nChannels; ++i) {
        mBuffers[i] = p;
        p += mCapacityBytes;
    }
    
    for (UInt32 i = 0; i<kGeneralRingTimeBoundsQueueSize; ++i)
    {
        mTimeBoundsQueue[i].mStartTime = 0;
        mTimeBoundsQueue[i].mEndTime = 0;
        mTimeBoundsQueue[i].mUpdateCounter = 0;
    }
    mTimeBoundsQueuePtr = 0;
}
 
void    CARingBuffer::Deallocate()
{
    if (mBuffers) {
        free(mBuffers);
        mBuffers = NULL;
    }
    mNumberChannels = 0;
    mCapacityBytes = 0;
    mCapacityFrames = 0;
}
 
inline void ZeroRange(Byte **buffers, int nchannels, int offset, int nbytes)
{
    while (--nchannels >= 0) {
        memset(*buffers + offset, 0, nbytes);
        ++buffers;
    }
}
 
inline void StoreABL(Byte **buffers, int destOffset, const AudioBufferList *abl, int srcOffset, int nbytes)
{
    int nchannels = abl->mNumberBuffers;
    const AudioBuffer *src = abl->mBuffers;
    while (--nchannels >= 0) {
        if (srcOffset > (int)src->mDataByteSize) continue;
        memcpy(*buffers + destOffset, (Byte *)src->mData + srcOffset, std::min(nbytes, (int)src->mDataByteSize - srcOffset));
        ++buffers;
        ++src;
    }
}
 
inline void FetchABL(AudioBufferList *abl, int destOffset, Byte **buffers, int srcOffset, int nbytes)
{
    int nchannels = abl->mNumberBuffers;
    AudioBuffer *dest = abl->mBuffers;
    while (--nchannels >= 0) {
        if (destOffset > (int)dest->mDataByteSize) continue;
        memcpy((Byte *)dest->mData + destOffset, *buffers + srcOffset, std::min(nbytes, (int)dest->mDataByteSize - destOffset));
        ++buffers;
        ++dest;
    }
}
 
inline void ZeroABL(AudioBufferList *abl, int destOffset, int nbytes)
{
    int nBuffers = abl->mNumberBuffers;
    AudioBuffer *dest = abl->mBuffers;
    while (--nBuffers >= 0) {
        if (destOffset > (int)dest->mDataByteSize) continue;
        memset((Byte *)dest->mData + destOffset, 0, std::min(nbytes, (int)dest->mDataByteSize - destOffset));
        ++dest;
    }
}
 
 
CARingBufferError   CARingBuffer::Store(const AudioBufferList *abl, UInt32 framesToWrite, SampleTime startWrite)
{
    if (framesToWrite == 0)
        return kCARingBufferError_OK;
    
    if (framesToWrite > mCapacityFrames)
        return kCARingBufferError_TooMuch;      // too big!
 
    SampleTime endWrite = startWrite + framesToWrite;
    
    if (startWrite < EndTime()) {
        // going backwards, throw everything out
        SetTimeBounds(startWrite, startWrite);
    } else if (endWrite - StartTime() <= mCapacityFrames) {
        // the buffer has not yet wrapped and will not need to
    } else {
        // advance the start time past the region we are about to overwrite
        SampleTime newStart = endWrite - mCapacityFrames;   // one buffer of time behind where we're writing
        SampleTime newEnd = std::max(newStart, EndTime());
        SetTimeBounds(newStart, newEnd);
    }
    
    // write the new frames
    Byte **buffers = mBuffers;
    int nchannels = mNumberChannels;
    int offset0, offset1, nbytes;
    SampleTime curEnd = EndTime();
    
    if (startWrite > curEnd) {
        // we are skipping some samples, so zero the range we are skipping
        offset0 = FrameOffset(curEnd);
        offset1 = FrameOffset(startWrite);
        if (offset0 < offset1)
            ZeroRange(buffers, nchannels, offset0, offset1 - offset0);
        else {
            ZeroRange(buffers, nchannels, offset0, mCapacityBytes - offset0);
            ZeroRange(buffers, nchannels, 0, offset1);
        }
        offset0 = offset1;
    } else {
        offset0 = FrameOffset(startWrite);
    }
 
    offset1 = FrameOffset(endWrite);
    if (offset0 < offset1)
        StoreABL(buffers, offset0, abl, 0, offset1 - offset0);
    else {
        nbytes = mCapacityBytes - offset0;
        StoreABL(buffers, offset0, abl, 0, nbytes);
        StoreABL(buffers, 0, abl, nbytes, offset1);
    }
    
    // now update the end time
    SetTimeBounds(StartTime(), endWrite);
    
    return kCARingBufferError_OK;   // success
}
 
void    CARingBuffer::SetTimeBounds(SampleTime startTime, SampleTime endTime)
{
    UInt32 nextPtr = mTimeBoundsQueuePtr + 1;
    UInt32 index = nextPtr & kGeneralRingTimeBoundsQueueMask;
    
    mTimeBoundsQueue[index].mStartTime = startTime;
    mTimeBoundsQueue[index].mEndTime = endTime;
    mTimeBoundsQueue[index].mUpdateCounter = nextPtr;
    CAAtomicCompareAndSwap32Barrier(mTimeBoundsQueuePtr, mTimeBoundsQueuePtr + 1, (SInt32*)&mTimeBoundsQueuePtr);
}
 
CARingBufferError   CARingBuffer::GetTimeBounds(SampleTime &startTime, SampleTime &endTime)
{
    for (int i=0; i<8; ++i) // fail after a few tries.
    {
        UInt32 curPtr = mTimeBoundsQueuePtr;
        UInt32 index = curPtr & kGeneralRingTimeBoundsQueueMask;
        CARingBuffer::TimeBounds* bounds = mTimeBoundsQueue + index;
        
        startTime = bounds->mStartTime;
        endTime = bounds->mEndTime;
        UInt32 newPtr = bounds->mUpdateCounter;
        
        if (newPtr == curPtr) 
            return kCARingBufferError_OK;
    }
    return kCARingBufferError_CPUOverload;
}
 
CARingBufferError   CARingBuffer::ClipTimeBounds(SampleTime& startRead, SampleTime& endRead)
{
    SampleTime startTime, endTime;
    
    CARingBufferError err = GetTimeBounds(startTime, endTime);
    if (err) return err;
    
    if (startRead > endTime || endRead < startTime) {
        endRead = startRead;
        return kCARingBufferError_OK;
    }
    
    startRead = std::max(startRead, startTime);
    endRead = std::min(endRead, endTime);
    endRead = std::max(endRead, startRead);
        
    return kCARingBufferError_OK;   // success
}
 
CARingBufferError   CARingBuffer::Fetch(AudioBufferList *abl, UInt32 nFrames, SampleTime startRead)
{
    if (nFrames == 0)
        return kCARingBufferError_OK;
        
    startRead = std::max(0LL, startRead);
    
    SampleTime endRead = startRead + nFrames;
 
    SampleTime startRead0 = startRead;
    SampleTime endRead0 = endRead;
 
    CARingBufferError err = ClipTimeBounds(startRead, endRead);
    if (err) return err;
 
    if (startRead == endRead) {
        ZeroABL(abl, 0, nFrames * mBytesPerFrame);
        return kCARingBufferError_OK;
    }
    
    SInt32 byteSize = (SInt32)((endRead - startRead) * mBytesPerFrame);
    
    SInt32 destStartByteOffset = std::max((SInt32)0, (SInt32)((startRead - startRead0) * mBytesPerFrame)); 
        
    if (destStartByteOffset > 0) {
        ZeroABL(abl, 0, std::min((SInt32)(nFrames * mBytesPerFrame), destStartByteOffset));
    }
 
    SInt32 destEndSize = std::max((SInt32)0, (SInt32)(endRead0 - endRead)); 
    if (destEndSize > 0) {
        ZeroABL(abl, destStartByteOffset + byteSize, destEndSize * mBytesPerFrame);
    }
    
    Byte **buffers = mBuffers;
    int offset0 = FrameOffset(startRead);
    int offset1 = FrameOffset(endRead);
    int nbytes;
    
    if (offset0 < offset1) {
        nbytes = offset1 - offset0;
        FetchABL(abl, destStartByteOffset, buffers, offset0, nbytes);
    } else {
        nbytes = mCapacityBytes - offset0;
        FetchABL(abl, destStartByteOffset, buffers, offset0, nbytes);
        FetchABL(abl, destStartByteOffset + nbytes, buffers, 0, offset1);
        nbytes += offset1;
    }
 
    int nchannels = abl->mNumberBuffers;
    AudioBuffer *dest = abl->mBuffers;
    while (--nchannels >= 0)
    {
        dest->mDataByteSize = nbytes;
        dest++;
    }
 
    return noErr;
}