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/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef BUFFER_SHARE_H_
#define BUFFER_SHARE_H_
#define INITIAL_ID_SIZE 3
struct id_offset {
unsigned int used;
unsigned int id;
unsigned int offset;
void *data;
};
struct buffer_share {
unsigned int buf_sz;
unsigned int id_sz;
struct id_offset *wr_idx;
};
/*
* Creates a buffer share object. This object is used to manage the read or
* write offsets of several users in one shared buffer.
*/
struct buffer_share *buffer_share_create(unsigned int buf_sz);
/* Destroys a buffer_share returned from buffer_share_create. */
void buffer_share_destroy(struct buffer_share *mix);
/* Adds an ID that shares the buffer. */
int buffer_share_add_id(struct buffer_share *mix, unsigned int id, void *data);
/* Removes an ID that shares the buffer. */
int buffer_share_rm_id(struct buffer_share *mix, unsigned int id);
/* Updates the offset of the given user into the shared buffer. */
int buffer_share_offset_update(struct buffer_share *mix, unsigned int id,
unsigned int frames);
/*
* Updates the write point to the minimum offset from all users.
* Returns the number of minimum number of frames written.
*/
unsigned int buffer_share_get_new_write_point(struct buffer_share *mix);
/*
* The amount by which the user given by id is ahead of the current write
* point.
*/
unsigned int buffer_share_id_offset(const struct buffer_share *mix,
unsigned int id);
/*
* Gets the data pointer for given id.
*/
void *buffer_share_get_data(const struct buffer_share *mix, unsigned int id);
#endif /* BUFFER_SHARE_H_ */
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