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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
/*
* $Id: ringbuffer.c,v 1.8 2006-08-18 19:00:59 millerpuckette Exp $
* ringbuffer.c
* Ring Buffer utility..
*
* Author: Phil Burk, http://www.softsynth.com
*
* This program uses the PortAudio Portable Audio Library.
* For more information see: http://www.audiomulch.com/portaudio/
* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* Any person wishing to distribute modifications to the Software is
* requested to send the modifications to the original developer so that
* they can be incorporated into the canonical version.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "ringbuffer.h"
#include <string.h>
/***************************************************************************
* Initialize FIFO.
* numBytes must be power of 2, returns -1 if not.
*/
long RingBuffer_Init( RingBuffer *rbuf, long numBytes, void *dataPtr )
{
if( ((numBytes-1) & numBytes) != 0) return -1; /* Not Power of two. */
rbuf->bufferSize = numBytes;
rbuf->buffer = (char *)dataPtr;
RingBuffer_Flush( rbuf );
rbuf->bigMask = (numBytes*2)-1;
rbuf->smallMask = (numBytes)-1;
return 0;
}
/***************************************************************************
** Return number of bytes available for reading. */
long RingBuffer_GetReadAvailable( RingBuffer *rbuf )
{
return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask );
}
/***************************************************************************
** Return number of bytes available for writing. */
long RingBuffer_GetWriteAvailable( RingBuffer *rbuf )
{
return ( rbuf->bufferSize - RingBuffer_GetReadAvailable(rbuf));
}
/***************************************************************************
** Clear buffer. Should only be called when buffer is NOT being read. */
void RingBuffer_Flush( RingBuffer *rbuf )
{
rbuf->writeIndex = rbuf->readIndex = 0;
}
/***************************************************************************
** Get address of region(s) to which we can write data.
** If the region is contiguous, size2 will be zero.
** If non-contiguous, size2 will be the size of second region.
** Returns room available to be written or numBytes, whichever is smaller.
*/
long RingBuffer_GetWriteRegions( RingBuffer *rbuf, long numBytes,
void **dataPtr1, long *sizePtr1,
void **dataPtr2, long *sizePtr2 )
{
long index;
long available = RingBuffer_GetWriteAvailable( rbuf );
if( numBytes > available ) numBytes = available;
/* Check to see if write is not contiguous. */
index = rbuf->writeIndex & rbuf->smallMask;
if( (index + numBytes) > rbuf->bufferSize )
{
/* Write data in two blocks that wrap the buffer. */
long firstHalf = rbuf->bufferSize - index;
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = firstHalf;
*dataPtr2 = &rbuf->buffer[0];
*sizePtr2 = numBytes - firstHalf;
}
else
{
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = numBytes;
*dataPtr2 = NULL;
*sizePtr2 = 0;
}
return numBytes;
}
/***************************************************************************
*/
long RingBuffer_AdvanceWriteIndex( RingBuffer *rbuf, long numBytes )
{
return rbuf->writeIndex = (rbuf->writeIndex + numBytes) & rbuf->bigMask;
}
/***************************************************************************
** Get address of region(s) from which we can read data.
** If the region is contiguous, size2 will be zero.
** If non-contiguous, size2 will be the size of second region.
** Returns room available to be written or numBytes, whichever is smaller.
*/
long RingBuffer_GetReadRegions( RingBuffer *rbuf, long numBytes,
void **dataPtr1, long *sizePtr1,
void **dataPtr2, long *sizePtr2 )
{
long index;
long available = RingBuffer_GetReadAvailable( rbuf );
if( numBytes > available ) numBytes = available;
/* Check to see if read is not contiguous. */
index = rbuf->readIndex & rbuf->smallMask;
if( (index + numBytes) > rbuf->bufferSize )
{
/* Write data in two blocks that wrap the buffer. */
long firstHalf = rbuf->bufferSize - index;
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = firstHalf;
*dataPtr2 = &rbuf->buffer[0];
*sizePtr2 = numBytes - firstHalf;
}
else
{
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = numBytes;
*dataPtr2 = NULL;
*sizePtr2 = 0;
}
return numBytes;
}
/***************************************************************************
*/
long RingBuffer_AdvanceReadIndex( RingBuffer *rbuf, long numBytes )
{
return rbuf->readIndex = (rbuf->readIndex + numBytes) & rbuf->bigMask;
}
/***************************************************************************
** Return bytes written. */
long RingBuffer_Write( RingBuffer *rbuf, void *data, long numBytes )
{
long size1, size2, numWritten;
void *data1, *data2;
numWritten = RingBuffer_GetWriteRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 );
if( size2 > 0 )
{
memcpy( data1, data, size1 );
data = ((char *)data) + size1;
memcpy( data2, data, size2 );
}
else
{
memcpy( data1, data, size1 );
}
RingBuffer_AdvanceWriteIndex( rbuf, numWritten );
return numWritten;
}
/***************************************************************************
** Return bytes read. */
long RingBuffer_Read( RingBuffer *rbuf, void *data, long numBytes )
{
long size1, size2, numRead;
void *data1, *data2;
numRead = RingBuffer_GetReadRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 );
if( size2 > 0 )
{
memcpy( data, data1, size1 );
data = ((char *)data) + size1;
memcpy( data, data2, size2 );
}
else
{
memcpy( data, data1, size1 );
}
RingBuffer_AdvanceReadIndex( rbuf, numRead );
return numRead;
}
|
