e9060e7e |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: au.h,v 1.1 2002/02/02 19:16:28 mdw Exp $ |
4 | * |
5 | * Audio handling |
6 | * |
7 | * (c) 2002 Mark Wooding |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Jog: Programming for a jogging machine. |
13 | * |
14 | * Jog is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * Jog is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with Jog; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: au.h,v $ |
32 | * Revision 1.1 2002/02/02 19:16:28 mdw |
33 | * New audio subsystem. |
34 | * |
35 | */ |
36 | |
37 | #ifndef AU_H |
38 | #define AU_H |
39 | |
40 | #ifdef __cplusplus |
41 | extern "C" { |
42 | #endif |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | #include <stddef.h> |
47 | |
48 | #include <mLib/bits.h> |
49 | #include <mLib/sym.h> |
50 | |
51 | /*----- Data structures ---------------------------------------------------*/ |
52 | |
53 | /* --- An audio sample --- * |
54 | * |
55 | * We maintain a cache of sample data, keyed by textual tags. An entry in |
56 | * the cache may indicate one of three states: |
57 | * |
58 | * * a tag for a sample which doesn't exist (negative answer); |
59 | * |
60 | * * a sample whose data is currently resident; or |
61 | * |
62 | * * sample with nonresident data. |
63 | * |
64 | * A negative answer is indicated by the @AUF_NOMATCH@ flag. If an entry has |
65 | * resident data, the @a@ pointer is non-null. |
66 | */ |
67 | |
68 | typedef struct au_sample { |
69 | sym_base s; /* Base structure for name lookup */ |
70 | unsigned f; /* Flags for this entry */ |
71 | struct au_data *a; /* Sample data, if present */ |
72 | } au_sample; |
73 | |
74 | #define AUF_NOMATCH 1u /* Cached non-match for this tag */ |
75 | |
76 | /* --- Audio data --- * |
77 | * |
78 | * The actual sample data, in an internal representation chosen by the |
79 | * system-specific layer. |
80 | * |
81 | * The sample data can be in one of two states: in-use or spare. Sample data |
82 | * is considered to be in-use if the @ref@ field is nonzero. Spare sample |
83 | * data is left in-memory for efficiency's sake, but will be discarded |
84 | * (least-recently-used first) when the total size of sample data (as |
85 | * measured by the @sz@ fields) exceeds @AU_CACHEMAX@. |
86 | */ |
87 | |
88 | typedef struct au_data { |
89 | struct au_data *next, *prev; /* Other samples in this list */ |
90 | unsigned ref; /* Reference count for sample data */ |
91 | struct au_sample *s; /* Parent sample node */ |
92 | octet *p; /* Pointer to sample file data */ |
93 | size_t sz; /* Size of sample file data */ |
94 | } au_data; |
95 | |
96 | #define AU_CACHEMAX 0x01000000 /* Maximum resident sample data */ |
97 | |
98 | /*----- Functions provided ------------------------------------------------*/ |
99 | |
100 | /* --- @au_init@ --- * |
101 | * |
102 | * Arguments: @const char *dir@ = samples directory, or null |
103 | * @size_t max@ = maximum cache size |
104 | * |
105 | * Returns: --- |
106 | * |
107 | * Use: Initializes the audio subsystem. |
108 | */ |
109 | |
110 | extern void au_init(const char */*dir*/, size_t /*max*/); |
111 | |
112 | /* --- @au_shutdown@ --- * |
113 | * |
114 | * Arguments: --- |
115 | * |
116 | * Returns: --- |
117 | * |
118 | * Use: Shuts down the audio subsystem. |
119 | */ |
120 | |
121 | extern void au_shutdown(void); |
122 | |
123 | /* --- @au_find@ --- * |
124 | * |
125 | * Arguments: @const char *tag@ = sample tag string |
126 | * |
127 | * Returns: A pointer to the sample corresponding to the tag, or null if |
128 | * the sample wasn't found. |
129 | * |
130 | * Use: Looks up a sample by its name. |
131 | */ |
132 | |
133 | extern au_sample *au_find(const char */*tag*/); |
134 | |
135 | /* --- @au_fetch@ --- * |
136 | * |
137 | * Arguments: @au_sample *s@ = sample pointer |
138 | * |
139 | * Returns: A pointer to the audio data for the sample. |
140 | * |
141 | * Use: Fetches a sample, and decodes it, if necessary. The decoded |
142 | * sample data is left with an outstanding reference to it, so |
143 | * it won't be freed. This is used internally by @au_queue@, |
144 | * before passing the fetched sample data to the system-specific |
145 | * layer for playback. It can also be used to lock sample data |
146 | * in memory (e.g., for the `abort' error message), or (by |
147 | * freeing it immediately afterwards) to prefetch a sample which |
148 | * will be used soon, to reduce the latency before the sample is |
149 | * heard. |
150 | */ |
151 | |
152 | extern au_data *au_fetch(au_sample */*s*/); |
153 | |
154 | /* --- @au_queue@ --- * |
155 | * |
156 | * Arguments: @au_sample *s@ = sample pointer |
157 | * |
158 | * Returns: Zero on success, nonzero on failure. |
159 | * |
160 | * Use: Queues a sample to be played. |
161 | */ |
162 | |
163 | extern int au_queue(au_sample */*s*/); |
164 | |
165 | /* --- @au_free@, @au_free_unlocked@ --- * |
166 | * |
167 | * Arguments: @au_data *a@ = pointer to audio data block |
168 | * |
169 | * Returns: --- |
170 | * |
171 | * Use: Frees a sample data block when it's no longer required. |
172 | */ |
173 | |
174 | extern void au_free(au_data */*a*/); |
175 | extern void au_free_unlocked(au_data */*a*/); |
176 | |
177 | /* --- @au_play@, @au_tryplay@ --- * |
178 | * |
179 | * Arguments: @const char *tag@ = sample tag string |
180 | * |
181 | * Returns: Zero on success, nonzero on failure. |
182 | * |
183 | * Use: Convenience functions for queueing samples by tag. |
184 | * If @au_tryplay@ cannot find the requested sample, it returns |
185 | * a zero value; if @au_play@ cannot find the sample, it aborts |
186 | * the program. |
187 | */ |
188 | |
189 | extern int au_play(const char */*tag*/); |
190 | extern int au_tryplay(const char */*tag*/); |
191 | |
192 | /*----- That's all, folks -------------------------------------------------*/ |
193 | |
194 | #ifdef __cplusplus |
195 | } |
196 | #endif |
197 | |
198 | #endif |