Initial community commit

Src/nu/RingBuffer.cpp

@@ -0,0 +1,461 @@
+/*
+ *  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;
+}