www.pudn.com > Flirt.zip > ringbuffer.c

/* 
 Flirt, an SWF rendering library 
 Copyright (c) 2004-2006 Dave Hayden  
 All rights reserved. 
  
 http://www.opaque.net/flirt/ 
 
 This code is distributed under the two-clause BSD license. 
 Read the LICENSE file or visit the URL above for details 
*/ 
 
#include  
#include  
#include  
 
#include "ringbuffer.h" 
 
struct ringBuffer* 
newRingBuffer(int size) 
{ 
	struct ringBuffer* ring = malloc(sizeof(struct ringBuffer)); 
	 
	ring->buffer = malloc(sizeof(ddAudioSample) * size); 
	ring->bufferLength = size; 
	ring->loopOffset = size; 
	ring->readOffset = 0; 
	ring->writeOffset = 0; 
	ring->surplus = 0; 
	 
	return ring; 
} 
 
 
int 
ringBuffer_samplesRemaining(struct ringBuffer* ring) 
{ 
	return ring->bufferLength - ring->writeOffset; 
} 
 
 
void 
ringBuffer_loop(struct ringBuffer* ring) 
{ 
	if ( ring->readOffset < ring->surplus ) 
	{ 
		printf("Not enough free space to loop!"); 
		return; 
	} 
	 
	memcpy(ring->buffer, ring->buffer + ring->writeOffset, ring->surplus); 
 
	ring->loopOffset = ring->writeOffset; 
	ring->writeOffset = 0; 
} 
 
 
void 
ringBuffer_setSurplus(struct ringBuffer* ring, int surplus) 
{ 
	ring->surplus = surplus; 
} 
 
 
ddAudioSample* 
ringBuffer_getWriteBuffer(struct ringBuffer* ring) 
{ 
	return ring->buffer + ring->writeOffset; 
} 
 
 
void 
ringBuffer_advanceWriteOffset(struct ringBuffer* ring, int count) 
{ 
	ring->writeOffset += count; 
} 
 
 
void 
ringBuffer_writeSamplesToStream(struct ringBuffer* ring, unsigned char* stream, int samples) 
{ 
	short* output = (short*)stream; 
	 
	if ( ring->readOffset > ring->writeOffset ) 
	{ 
		ddAudioSample* p = ring->buffer + ring->readOffset; 
		ddAudioSample* end; 
		 
		if ( ring->readOffset + samples > ring->loopOffset ) 
			end = ring->buffer + ring->loopOffset; 
		else 
			end = ring->buffer + ring->readOffset + samples; 
		 
		while ( p < end ) 
		{ 
			*output++ = DD_SAMPLE_SINT16(p->left >> 8); 
			*output++ = DD_SAMPLE_SINT16(p->right >> 8); 
			++p; 
		} 
		 
		if ( end < ring->buffer + samples ) 
		{ 
			ring->readOffset += samples; 
			return; 
		} 
		 
		samples -= ring->loopOffset - ring->readOffset; 
		ring->readOffset = 0; 
	} 
	 
	if ( ring->readOffset < ring->writeOffset ) 
	{ 
		ddAudioSample* p = ring->buffer + ring->readOffset; 
		ddAudioSample* end; 
		 
		if ( ring->readOffset + samples > ring->writeOffset ) 
		{ 
			printf("audio underflow\n"); 
			samples = ring->writeOffset - ring->readOffset; 
		} 
		 
		end = ring->buffer + ring->readOffset + samples; 
		 
		while ( p < end ) 
		{ 
			*output++ = DD_SAMPLE_SINT16(p->left >> 16); 
			*output++ = DD_SAMPLE_SINT16(p->right >> 16); 
			++p; 
		} 
		 
		ring->readOffset += samples; 
	} 
}