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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
/*
* Copyright (C) 2003-2011 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "decoder_buffer.h"
#include "decoder_api.h"
#include <glib.h>
#include <assert.h>
struct decoder_buffer {
struct decoder *decoder;
struct input_stream *is;
/** the allocated size of the buffer */
size_t size;
/** the current length of the buffer */
size_t length;
/** number of bytes already consumed at the beginning of the
buffer */
size_t consumed;
/** the actual buffer (dynamic size) */
unsigned char data[sizeof(size_t)];
};
struct decoder_buffer *
decoder_buffer_new(struct decoder *decoder, struct input_stream *is,
size_t size)
{
struct decoder_buffer *buffer =
g_malloc(sizeof(*buffer) - sizeof(buffer->data) + size);
assert(is != NULL);
assert(size > 0);
buffer->decoder = decoder;
buffer->is = is;
buffer->size = size;
buffer->length = 0;
buffer->consumed = 0;
return buffer;
}
void
decoder_buffer_free(struct decoder_buffer *buffer)
{
assert(buffer != NULL);
g_free(buffer);
}
bool
decoder_buffer_is_empty(const struct decoder_buffer *buffer)
{
return buffer->consumed == buffer->length;
}
bool
decoder_buffer_is_full(const struct decoder_buffer *buffer)
{
return buffer->consumed == 0 && buffer->length == buffer->size;
}
static void
decoder_buffer_shift(struct decoder_buffer *buffer)
{
assert(buffer->consumed > 0);
buffer->length -= buffer->consumed;
memmove(buffer->data, buffer->data + buffer->consumed, buffer->length);
buffer->consumed = 0;
}
bool
decoder_buffer_fill(struct decoder_buffer *buffer)
{
size_t nbytes;
if (buffer->consumed > 0)
decoder_buffer_shift(buffer);
if (buffer->length >= buffer->size)
/* buffer is full */
return false;
nbytes = decoder_read(buffer->decoder, buffer->is,
buffer->data + buffer->length,
buffer->size - buffer->length);
if (nbytes == 0)
/* end of file, I/O error or decoder command
received */
return false;
buffer->length += nbytes;
assert(buffer->length <= buffer->size);
return true;
}
const void *
decoder_buffer_read(const struct decoder_buffer *buffer, size_t *length_r)
{
if (buffer->consumed >= buffer->length)
/* buffer is empty */
return NULL;
*length_r = buffer->length - buffer->consumed;
return buffer->data + buffer->consumed;
}
void
decoder_buffer_consume(struct decoder_buffer *buffer, size_t nbytes)
{
/* just move the "consumed" pointer - decoder_buffer_shift()
will do the real work later (called by
decoder_buffer_fill()) */
buffer->consumed += nbytes;
assert(buffer->consumed <= buffer->length);
}
bool
decoder_buffer_skip(struct decoder_buffer *buffer, size_t nbytes)
{
size_t length;
const void *data;
bool success;
/* this could probably be optimized by seeking */
while (true) {
data = decoder_buffer_read(buffer, &length);
if (data != NULL) {
if (length > nbytes)
length = nbytes;
decoder_buffer_consume(buffer, length);
nbytes -= length;
if (nbytes == 0)
return true;
}
success = decoder_buffer_fill(buffer);
if (!success)
return false;
}
}
|
