1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
/*
* Copyright (C) 2003-2010 The Music Player Daemon Project
* http://www.musicpd.org
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** \file
*
* This is a general purpose FIFO buffer library. You may append data
* at the end, while another instance reads data from the beginning.
* It is optimized for zero-copy usage: you get pointers to the real
* buffer, where you may operate on.
*
* This library is not thread safe.
*/
#ifndef MPD_FIFO_BUFFER_H
#define MPD_FIFO_BUFFER_H
#include <stdbool.h>
#include <stddef.h>
struct fifo_buffer;
/**
* Creates a new #fifo_buffer object. Free this object with
* fifo_buffer_free().
*
* @param size the size of the buffer in bytes
* @return the new #fifo_buffer object
*/
struct fifo_buffer *
fifo_buffer_new(size_t size);
/**
* Frees the resources consumed by this #fifo_buffer object.
*/
void
fifo_buffer_free(struct fifo_buffer *buffer);
/**
* Clears all data currently in this #fifo_buffer object. This does
* not overwrite the actuall buffer; it just resets the internal
* pointers.
*/
void
fifo_buffer_clear(struct fifo_buffer *buffer);
/**
* Reads from the beginning of the buffer. To remove consumed data
* from the buffer, call fifo_buffer_consume().
*
* @param buffer the #fifo_buffer object
* @param length_r the maximum amount to read is returned here
* @return a pointer to the beginning of the buffer, or NULL if the
* buffer is empty
*/
const void *
fifo_buffer_read(const struct fifo_buffer *buffer, size_t *length_r);
/**
* Marks data at the beginning of the buffer as "consumed".
*
* @param buffer the #fifo_buffer object
* @param length the number of bytes which were consumed
*/
void
fifo_buffer_consume(struct fifo_buffer *buffer, size_t length);
/**
* Prepares writing to the buffer. This returns a buffer which you
* can write to. To commit the write operation, call
* fifo_buffer_append().
*
* @param buffer the #fifo_buffer object
* @param max_length_r the maximum amount to write is returned here
* @return a pointer to the end of the buffer, or NULL if the buffer
* is already full
*/
void *
fifo_buffer_write(struct fifo_buffer *buffer, size_t *max_length_r);
/**
* Commits the write operation initiated by fifo_buffer_write().
*
* @param buffer the #fifo_buffer object
* @param length the number of bytes which were written
*/
void
fifo_buffer_append(struct fifo_buffer *buffer, size_t length);
/**
* Checks if the buffer is empty.
*/
bool
fifo_buffer_is_empty(struct fifo_buffer *buffer);
/**
* Checks if the buffer is full.
*/
bool
fifo_buffer_is_full(struct fifo_buffer *buffer);
#endif
|
