/*
* RingBuffer.cpp
* simple_mp3_playback
*
* Created by Ben Allison on 11/10/07.
* Copyright 2007 Nullsoft, Inc. All rights reserved.
*
*/
#include "RingBuffer.h"
#include "../replicant/foundation/error.h"
#include "bfc/platform/types.h"
#include "bfc/platform/minmax.h"
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#ifdef MIN
#undef MIN
#endif // MIN
#define MIN(a,b) ((a<b)?(a):(b))
RingBuffer::~RingBuffer()
{
if ( ringBuffer )
free( ringBuffer );
ringBuffer = 0;
}
void RingBuffer::Reset()
{
if ( ringBuffer )
free( ringBuffer );
ringBuffer = 0;
}
bool RingBuffer::reserve( size_t bytes )
{
Reset();
ringBufferSize = bytes;
ringBuffer = (char *)calloc( ringBufferSize, sizeof( char ) );
if ( !ringBuffer )
return false;
clear();
return true;
}
int RingBuffer::expand( size_t bytes )
{
if ( bytes > ringBufferSize )
{
char *new_buffer = (char *)realloc( ringBuffer, bytes );
if ( !new_buffer )
return NErr_OutOfMemory;
size_t write_offset = ringReadPosition - ringBuffer;
size_t read_offset = ringWritePosition - ringBuffer;
/* update write pointer for the new buffer */
ringWritePosition = new_buffer + write_offset;
if ( write_offset > read_offset || !ringBufferUsed ) /* ringBufferUsed will resolve the ambiguity when ringWritePosition == ringReadPosition */
{
/* the ring buffer looks like [ RXXXW ], so we don't need to move anything.
Just update the read pointer */
ringReadPosition = new_buffer + write_offset;
}
else
{
/* [XXW RXX] needs to become [XXW RXX] */
size_t end_bytes = ringBufferSize - read_offset; // number of bytes that we need to relocate (the RXX portion)
char *new_read_pointer = &new_buffer[ bytes - end_bytes ];
memmove( new_read_pointer, ringReadPosition, end_bytes );
ringReadPosition = new_read_pointer; /* update read pointer */
}
ringBufferSize = bytes;
ringBuffer = new_buffer;
return NErr_Success;
}
else
return NErr_NoAction;
}
bool RingBuffer::empty() const
{
return ( ringBufferUsed == 0 );
}
size_t RingBuffer::read( void *dest, size_t len )
{
int8_t *out = (int8_t *)dest; // lets us do pointer math easier
size_t toCopy = MIN( ringBufferUsed, len );
size_t copied = 0;
len -= toCopy;
// read to the end of the ring buffer
size_t end = ringBufferSize - ( ringReadPosition - ringBuffer );
size_t read1 = MIN( end, toCopy );
memcpy( out, ringReadPosition, read1 );
copied += read1;
ringReadPosition += read1;
if ( ringReadPosition == ringBuffer + ringBufferSize )
ringReadPosition = ringBuffer;
// update positions
ringBufferUsed -= read1;
toCopy -= read1;
out = (int8_t *)out + read1;
// see if we still have more to read after wrapping around
if ( toCopy )
{
memcpy( out, ringReadPosition, toCopy );
copied += toCopy;
ringReadPosition += toCopy;
ringBufferUsed -= toCopy;
if ( ringReadPosition == ringBuffer + ringBufferSize )
ringReadPosition = ringBuffer;
}
return copied;
}
size_t RingBuffer::at(size_t offset, void *dest, size_t len) const
{
size_t toCopy = ringBufferUsed;
// make a local copy of this so we don't blow the original
char *ringReadPosition = this->ringReadPosition;
/* --- do a "dummy read" to deal with the offset request --- */
size_t dummy_end = ringBufferSize-(ringReadPosition-ringBuffer);
offset = MIN(toCopy, offset);
size_t read0 = MIN(dummy_end, offset);
ringReadPosition+=read0;
if (ringReadPosition == ringBuffer + ringBufferSize)
ringReadPosition = ringBuffer;
// update positions
toCopy -= read0;
offset -= read0;
// do second-half read (wraparound)
if ( offset )
{
ringReadPosition += offset;
toCopy -= offset;
}
// dummy read done
/* --- set up destination buffer and copy size --- */
int8_t *out = (int8_t *)dest; // lets us do pointer math easier
if ( toCopy > len )
toCopy = len;
size_t copied=0;
/* --- read to the end of the ring buffer --- */
size_t end = ringBufferSize - ( ringReadPosition - ringBuffer );
size_t read1 = MIN( end, toCopy );
memcpy( out, ringReadPosition, read1 );
copied += read1;
ringReadPosition += read1;
if (ringReadPosition == ringBuffer + ringBufferSize)
ringReadPosition = ringBuffer;
// update positions
toCopy -= read1;
out = (int8_t *)out + read1;
/* --- see if we still have more to read after wrapping around --- */
if (toCopy)
{
memcpy(out, ringReadPosition, toCopy);
copied += toCopy;
ringReadPosition += toCopy;
}
return copied;
}
size_t RingBuffer::peek( void *dest, size_t len ) const
{
int8_t *out = (int8_t *)dest; // lets us do pointer math easier
size_t toCopy = MIN( ringBufferUsed, len );
size_t copied = 0;
// make a local copy of this so we don't blow the original
char *ringReadPosition = this->ringReadPosition;
// read to the end of the ring buffer
size_t end = ringBufferSize - ( ringReadPosition - ringBuffer );
size_t read1 = MIN( end, toCopy );
memcpy( out, ringReadPosition, read1 );
copied += read1;
ringReadPosition += read1;
if ( ringReadPosition == ringBuffer + ringBufferSize )
ringReadPosition = ringBuffer;
// update positions
toCopy -= read1;
out = (int8_t *)out + read1;
// see if we still have more to read after wrapping around
if ( toCopy )
{
memcpy( out, ringReadPosition, toCopy );
copied += toCopy;
ringReadPosition += toCopy;
}
return copied;
}
size_t RingBuffer::advance( size_t len )
{
size_t toCopy = MIN( ringBufferUsed, len );
size_t copied = 0;
len -= toCopy;
// read to the end of the ring buffer
size_t end = ringBufferSize - ( ringReadPosition - ringBuffer );
size_t read1 = MIN( end, toCopy );
copied += read1;
ringReadPosition += read1;
if ( ringReadPosition == ringBuffer + ringBufferSize )
ringReadPosition = ringBuffer;
// update positions
toCopy -= read1;
ringBufferUsed -= read1;
// see if we still have more to read after wrapping around
if ( toCopy )
{
copied += toCopy;
ringReadPosition += toCopy;
ringBufferUsed -= toCopy;
if ( ringReadPosition == ringBuffer + ringBufferSize )
ringReadPosition = ringBuffer;
}
return copied;
}
size_t RingBuffer::avail() const
{
return ringBufferSize - ringBufferUsed;
}
size_t RingBuffer::write( const void *buffer, size_t bytes )
{
size_t used = ringBufferUsed;
size_t avail = ringBufferSize - used;
bytes = MIN( avail, bytes );
// write to the end of the ring buffer
size_t end = ringBufferSize - ( ringWritePosition - ringBuffer );
size_t copied = 0;
size_t write1 = MIN( end, bytes );
memcpy( ringWritePosition, buffer, write1 );
copied += write1;
ringWritePosition += write1;
if ( ringWritePosition == ringBuffer + ringBufferSize )
ringWritePosition = ringBuffer;
// update positions
ringBufferUsed += write1;
bytes -= write1;
buffer = (const int8_t *)buffer + write1;
// see if we still have more to write after wrapping around
if ( bytes )
{
memcpy( ringWritePosition, buffer, bytes );
copied += bytes;
ringWritePosition += bytes;
ringBufferUsed += bytes;
if ( ringWritePosition == ringBuffer + ringBufferSize )
ringWritePosition = ringBuffer;
}
return copied;
}
size_t RingBuffer::drain( Drainer *drainer, size_t max_bytes )
{
// read to the end of the ring buffer
size_t used = ringBufferUsed;
size_t bytes = used;
bytes = MIN(bytes, max_bytes);
size_t copied = 0;
size_t end = ringBufferSize-(ringReadPosition-ringBuffer);
size_t drain1 = MIN(end, bytes);
if (!drain1)
return 0;
size_t read1 = drainer->Write(ringReadPosition, drain1);
if (read1 == 0)
return 0;
copied+=read1;
ringReadPosition+=read1;
if (ringReadPosition == ringBuffer + ringBufferSize)
ringReadPosition=ringBuffer;
// update positions
ringBufferUsed -= read1;
bytes-=read1;
// see if we still have more to read after wrapping around
if (drain1 == read1 && bytes)
{
size_t read2 = drainer->Write(ringReadPosition, bytes);
copied += read2;
ringReadPosition += read2;
ringBufferUsed -= read2;
if (ringReadPosition == ringBuffer + ringBufferSize)
ringReadPosition=ringBuffer;
}
return copied;
}
size_t RingBuffer::fill(Filler *filler, size_t max_bytes)
{
// write to the end of the ring buffer
size_t used = ringBufferUsed;
size_t bytes = ringBufferSize - used;
bytes = MIN(bytes, max_bytes);
size_t copied = 0;
size_t end = ringBufferSize-(ringWritePosition-ringBuffer);
size_t fill1 = MIN(end, bytes);
if (!fill1)
return 0;
size_t write1 = filler->Read(ringWritePosition, fill1);
if (write1 == 0)
return 0;
copied+=write1;
ringWritePosition+=write1;
if (ringWritePosition == ringBuffer + ringBufferSize)
ringWritePosition=ringBuffer;
// update positions
ringBufferUsed += write1;
bytes-=write1;
// see if we still have more to write after wrapping around
if (fill1 == write1 && bytes)
{
size_t write2 = filler->Read(ringWritePosition, bytes);
copied += write2;
ringWritePosition += write2;
ringBufferUsed += write2;
if (ringWritePosition == ringBuffer + ringBufferSize)
ringWritePosition=ringBuffer;
}
return copied;
}
size_t RingBuffer::size() const
{
return ringBufferUsed;
}
void RingBuffer::clear()
{
ringBufferUsed = 0;
ringWritePosition = ringBuffer;
ringReadPosition = ringBuffer;
}
void *RingBuffer::LockBuffer()
{
return ringBuffer;
}
void RingBuffer::UnlockBuffer( size_t written )
{
ringWritePosition = ringBuffer+written;
ringBufferUsed = written;
}
size_t RingBuffer::write_position() const
{
return (size_t)ringWritePosition;
}
size_t RingBuffer::read_position() const
{
return (size_t)ringReadPosition;
}
void RingBuffer::get_read_buffer(size_t bytes, const void **buffer, size_t *bytes_available) const
{
size_t toCopy = MIN( ringBufferUsed, bytes );
// read to the end of the ring buffer
size_t end = ringBufferSize-(ringReadPosition-ringBuffer);
*bytes_available = MIN(end, toCopy);
*buffer = ringReadPosition;
}
