1 #ifndef PA_STREAM_H
2 #define PA_STREAM_H
3 /*
4  * $Id$
5  * Portable Audio I/O Library
6  * stream interface
7  *
8  * Based on the Open Source API proposed by Ross Bencina
9  * Copyright (c) 1999-2008 Ross Bencina, Phil Burk
10  *
11  * Permission is hereby granted, free of charge, to any person obtaining
12  * a copy of this software and associated documentation files
13  * (the "Software"), to deal in the Software without restriction,
14  * including without limitation the rights to use, copy, modify, merge,
15  * publish, distribute, sublicense, and/or sell copies of the Software,
16  * and to permit persons to whom the Software is furnished to do so,
17  * subject to the following conditions:
18  *
19  * The above copyright notice and this permission notice shall be
20  * included in all copies or substantial portions of the Software.
21  *
22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
23  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
25  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
26  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
27  * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
28  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29  */
30 
31 /*
32  * The text above constitutes the entire PortAudio license; however,
33  * the PortAudio community also makes the following non-binding requests:
34  *
35  * Any person wishing to distribute modifications to the Software is
36  * requested to send the modifications to the original developer so that
37  * they can be incorporated into the canonical version. It is also
38  * requested that these non-binding requests be included along with the
39  * license above.
40  */
41 
42 /** @file
43  @ingroup common_src
44 
45  @brief Stream interfaces, representation structures and helper functions
46  used to interface between pa_front.c host API implementations.
47 */
48 
49 
50 #include "portaudio.h"
51 
52 #ifdef __cplusplus
53 extern "C"
54 {
55 #endif /* __cplusplus */
56 
57 
58 #define PA_STREAM_MAGIC (0x18273645)
59 
60 
61 /** A structure representing an (abstract) interface to a host API. Contains
62  pointers to functions which implement the interface.
63 
64  All PaStreamInterface functions are guaranteed to be called with a non-null,
65  valid stream parameter.
66 */
67 typedef struct {
68     PaError (*Close)( PaStream* stream );
69     PaError (*Start)( PaStream *stream );
70     PaError (*Stop)( PaStream *stream );
71     PaError (*Abort)( PaStream *stream );
72     PaError (*IsStopped)( PaStream *stream );
73     PaError (*IsActive)( PaStream *stream );
74     PaTime (*GetTime)( PaStream *stream );
75     double (*GetCpuLoad)( PaStream* stream );
76     PaError (*Read)( PaStream* stream, void *buffer, unsigned long frames );
77     PaError (*Write)( PaStream* stream, const void *buffer, unsigned long frames );
78     signed long (*GetReadAvailable)( PaStream* stream );
79     signed long (*GetWriteAvailable)( PaStream* stream );
80 } PaUtilStreamInterface;
81 
82 
83 /** Initialize the fields of a PaUtilStreamInterface structure.
84 */
85 void PaUtil_InitializeStreamInterface( PaUtilStreamInterface *streamInterface,
86     PaError (*Close)( PaStream* ),
87     PaError (*Start)( PaStream* ),
88     PaError (*Stop)( PaStream* ),
89     PaError (*Abort)( PaStream* ),
90     PaError (*IsStopped)( PaStream* ),
91     PaError (*IsActive)( PaStream* ),
92     PaTime (*GetTime)( PaStream* ),
93     double (*GetCpuLoad)( PaStream* ),
94     PaError (*Read)( PaStream* stream, void *buffer, unsigned long frames ),
95     PaError (*Write)( PaStream* stream, const void *buffer, unsigned long frames ),
96     signed long (*GetReadAvailable)( PaStream* stream ),
97     signed long (*GetWriteAvailable)( PaStream* stream ) );
98 
99 
100 /** Dummy Read function for use in interfaces to a callback based streams.
101  Pass to the Read parameter of PaUtil_InitializeStreamInterface.
102  @return An error code indicating that the function has no effect
103  because the stream is a callback stream.
104 */
105 PaError PaUtil_DummyRead( PaStream* stream,
106                        void *buffer,
107                        unsigned long frames );
108 
109 
110 /** Dummy Write function for use in an interfaces to callback based streams.
111  Pass to the Write parameter of PaUtil_InitializeStreamInterface.
112  @return An error code indicating that the function has no effect
113  because the stream is a callback stream.
114 */
115 PaError PaUtil_DummyWrite( PaStream* stream,
116                        const void *buffer,
117                        unsigned long frames );
118 
119 
120 /** Dummy GetReadAvailable function for use in interfaces to callback based
121  streams. Pass to the GetReadAvailable parameter of PaUtil_InitializeStreamInterface.
122  @return An error code indicating that the function has no effect
123  because the stream is a callback stream.
124 */
125 signed long PaUtil_DummyGetReadAvailable( PaStream* stream );
126 
127 
128 /** Dummy GetWriteAvailable function for use in interfaces to callback based
129  streams. Pass to the GetWriteAvailable parameter of PaUtil_InitializeStreamInterface.
130  @return An error code indicating that the function has no effect
131  because the stream is a callback stream.
132 */
133 signed long PaUtil_DummyGetWriteAvailable( PaStream* stream );
134 
135 
136 
137 /** Dummy GetCpuLoad function for use in an interface to a read/write stream.
138  Pass to the GetCpuLoad parameter of PaUtil_InitializeStreamInterface.
139  @return Returns 0.
140 */
141 double PaUtil_DummyGetCpuLoad( PaStream* stream );
142 
143 
144 /** Non host specific data for a stream. This data is used by pa_front to
145  forward to the appropriate functions in the streamInterface structure.
146 */
147 typedef struct PaUtilStreamRepresentation {
148     unsigned long magic;    /**< set to PA_STREAM_MAGIC */
149     struct PaUtilStreamRepresentation *nextOpenStream; /**< field used by multi-api code */
150     PaUtilStreamInterface *streamInterface;
151     PaStreamCallback *streamCallback;
152     PaStreamFinishedCallback *streamFinishedCallback;
153     void *userData;
154     PaStreamInfo streamInfo;
155 } PaUtilStreamRepresentation;
156 
157 
158 /** Initialize a PaUtilStreamRepresentation structure.
159 
160  @see PaUtil_InitializeStreamRepresentation
161 */
162 void PaUtil_InitializeStreamRepresentation(
163         PaUtilStreamRepresentation *streamRepresentation,
164         PaUtilStreamInterface *streamInterface,
165         PaStreamCallback *streamCallback,
166         void *userData );
167 
168 
169 /** Clean up a PaUtilStreamRepresentation structure previously initialized
170  by a call to PaUtil_InitializeStreamRepresentation.
171 
172  @see PaUtil_InitializeStreamRepresentation
173 */
174 void PaUtil_TerminateStreamRepresentation( PaUtilStreamRepresentation *streamRepresentation );
175 
176 
177 /** Check that the stream pointer is valid.
178 
179  @return Returns paNoError if the stream pointer appears to be OK, otherwise
180  returns an error indicating the cause of failure.
181 */
182 PaError PaUtil_ValidateStreamPointer( PaStream *stream );
183 
184 
185 /** Cast an opaque stream pointer into a pointer to a PaUtilStreamRepresentation.
186 
187  @see PaUtilStreamRepresentation
188 */
189 #define PA_STREAM_REP( stream )\
190     ((PaUtilStreamRepresentation*) (stream) )
191 
192 
193 /** Cast an opaque stream pointer into a pointer to a PaUtilStreamInterface.
194 
195  @see PaUtilStreamRepresentation, PaUtilStreamInterface
196 */
197 #define PA_STREAM_INTERFACE( stream )\
198     PA_STREAM_REP( (stream) )->streamInterface
199 
200 
201 
202 #ifdef __cplusplus
203 }
204 #endif /* __cplusplus */
205 #endif /* PA_STREAM_H */
206