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/* FluidSynth - A Software Synthesizer
*
* Copyright (C) 2003 Peter Hanappe and others.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License
* as published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*/
#ifndef _FLUID_RINGBUFFER_H
#define _FLUID_RINGBUFFER_H
#include "fluid_sys.h"
/**
* Lockless event queue instance.
*/
struct _fluid_ringbuffer_t
{
char *array; /**< Queue array of arbitrary size elements */
int totalcount; /**< Total count of elements in array */
int count; /**< Current count of elements */
int in; /**< Index in queue to store next pushed element */
int out; /**< Index in queue of next popped element */
int elementsize; /**< Size of each element */
void* userdata;
};
typedef struct _fluid_ringbuffer_t fluid_ringbuffer_t;
fluid_ringbuffer_t *new_fluid_ringbuffer (int count, int elementsize);
void delete_fluid_ringbuffer (fluid_ringbuffer_t *queue);
/**
* Get pointer to next input array element in queue.
* @param queue Lockless queue instance
* @param count Normally zero, or more if you need to push several items at once
* @return Pointer to array element in queue to store data to or NULL if queue is full
*
* This function along with fluid_ringbuffer_next_inptr() form a queue "push"
* operation and is split into 2 functions to avoid an element copy. Note that
* the returned array element pointer may contain the data of a previous element
* if the queue has wrapped around. This can be used to reclaim pointers to
* allocated memory, etc.
*/
static FLUID_INLINE void*
fluid_ringbuffer_get_inptr (fluid_ringbuffer_t *queue, int offset)
{
return fluid_atomic_int_get (&queue->count) + offset >= queue->totalcount ? NULL
: queue->array + queue->elementsize * ((queue->in + offset) % queue->totalcount);
}
/**
* Advance the input queue index to complete a "push" operation.
* @param queue Lockless queue instance
* @param count Normally one, or more if you need to push several items at once
*
* This function along with fluid_ringbuffer_get_inptr() form a queue "push"
* operation and is split into 2 functions to avoid element copy.
*/
static FLUID_INLINE void
fluid_ringbuffer_next_inptr (fluid_ringbuffer_t *queue, int count)
{
fluid_atomic_int_add (&queue->count, count);
queue->in += count;
if (queue->in >= queue->totalcount)
queue->in -= queue->totalcount;
}
/**
* Get amount of items currently in queue
* @param queue Lockless queue instance
* @return amount of items currently in queue
*/
static FLUID_INLINE int
fluid_ringbuffer_get_count (fluid_ringbuffer_t *queue)
{
return fluid_atomic_int_get (&queue->count);
}
/**
* Get pointer to next output array element in queue.
* @param queue Lockless queue instance
* @return Pointer to array element data in the queue or NULL if empty, can only
* be used up until fluid_ringbuffer_next_outptr() is called.
*
* This function along with fluid_ringbuffer_next_outptr() form a queue "pop"
* operation and is split into 2 functions to avoid an element copy.
*/
static FLUID_INLINE void*
fluid_ringbuffer_get_outptr (fluid_ringbuffer_t *queue)
{
return fluid_ringbuffer_get_count(queue) == 0 ? NULL
: queue->array + queue->elementsize * queue->out;
}
/**
* Advance the output queue index to complete a "pop" operation.
* @param queue Lockless queue instance
*
* This function along with fluid_ringbuffer_get_outptr() form a queue "pop"
* operation and is split into 2 functions to avoid an element copy.
*/
static FLUID_INLINE void
fluid_ringbuffer_next_outptr (fluid_ringbuffer_t *queue)
{
fluid_atomic_int_add (&queue->count, -1);
if (++queue->out == queue->totalcount)
queue->out = 0;
}
#endif /* _FLUID_ringbuffer_H */
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