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comparison DPF-Prymula-audioplugins/dpf/distrho/src/lv2/state.h @ 3:84e66ea83026

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DPF-Prymula-audioplugins-0.231015-2
author prymula <prymula76@outlook.com>
date Mon, 16 Oct 2023 21:53:34 +0200
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2:cf2cb71d31dd 3:84e66ea83026
1 /*
2 Copyright 2010-2016 David Robillard <http://drobilla.net>
3 Copyright 2010 Leonard Ritter <paniq@paniq.org>
4
5 Permission to use, copy, modify, and/or distribute this software for any
6 purpose with or without fee is hereby granted, provided that the above
7 copyright notice and this permission notice appear in all copies.
8
9 THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 /**
19 @defgroup state State
20 @ingroup lv2
21
22 An interface for LV2 plugins to save and restore state, see
23 <http://lv2plug.in/ns/ext/state> for details.
24
25 @{
26 */
27
28 #ifndef LV2_STATE_H
29 #define LV2_STATE_H
30
31 #include "lv2.h"
32
33 #include <stdbool.h>
34 #include <stddef.h>
35 #include <stdint.h>
36
37 #define LV2_STATE_URI "http://lv2plug.in/ns/ext/state" ///< http://lv2plug.in/ns/ext/state
38 #define LV2_STATE_PREFIX LV2_STATE_URI "#" ///< http://lv2plug.in/ns/ext/state#
39
40 #define LV2_STATE__State LV2_STATE_PREFIX "State" ///< http://lv2plug.in/ns/ext/state#State
41 #define LV2_STATE__interface LV2_STATE_PREFIX "interface" ///< http://lv2plug.in/ns/ext/state#interface
42 #define LV2_STATE__loadDefaultState LV2_STATE_PREFIX "loadDefaultState" ///< http://lv2plug.in/ns/ext/state#loadDefaultState
43 #define LV2_STATE__freePath LV2_STATE_PREFIX "freePath" ///< http://lv2plug.in/ns/ext/state#freePath
44 #define LV2_STATE__makePath LV2_STATE_PREFIX "makePath" ///< http://lv2plug.in/ns/ext/state#makePath
45 #define LV2_STATE__mapPath LV2_STATE_PREFIX "mapPath" ///< http://lv2plug.in/ns/ext/state#mapPath
46 #define LV2_STATE__state LV2_STATE_PREFIX "state" ///< http://lv2plug.in/ns/ext/state#state
47 #define LV2_STATE__threadSafeRestore LV2_STATE_PREFIX "threadSafeRestore" ///< http://lv2plug.in/ns/ext/state#threadSafeRestore
48 #define LV2_STATE__StateChanged LV2_STATE_PREFIX "StateChanged" ///< http://lv2plug.in/ns/ext/state#StateChanged
49
50 #ifdef __cplusplus
51 extern "C" {
52 #endif
53
54 typedef void* LV2_State_Handle; ///< Opaque handle for state save/restore
55 typedef void* LV2_State_Free_Path_Handle; ///< Opaque handle for state:freePath feature
56 typedef void* LV2_State_Map_Path_Handle; ///< Opaque handle for state:mapPath feature
57 typedef void* LV2_State_Make_Path_Handle; ///< Opaque handle for state:makePath feature
58
59 /**
60 Flags describing value characteristics.
61
62 These flags are used along with the value's type URI to determine how to
63 (de-)serialise the value data, or whether it is even possible to do so.
64 */
65 typedef enum {
66 /**
67 Plain Old Data.
68
69 Values with this flag contain no pointers or references to other areas
70 of memory. It is safe to copy POD values with a simple memcpy and store
71 them for the duration of the process. A POD value is not necessarily
72 safe to trasmit between processes or machines (for example, filenames
73 are POD), see LV2_STATE_IS_PORTABLE for details.
74
75 Implementations MUST NOT attempt to copy or serialise a non-POD value if
76 they do not understand its type (and thus know how to correctly do so).
77 */
78 LV2_STATE_IS_POD = 1,
79
80 /**
81 Portable (architecture independent) data.
82
83 Values with this flag are in a format that is usable on any
84 architecture. A portable value saved on one machine can be restored on
85 another machine regardless of architecture. The format of portable
86 values MUST NOT depend on architecture-specific properties like
87 endianness or alignment. Portable values MUST NOT contain filenames.
88 */
89 LV2_STATE_IS_PORTABLE = 1 << 1,
90
91 /**
92 Native data.
93
94 This flag is used by the host to indicate that the saved data is only
95 going to be used locally in the currently running process (for things
96 like instance duplication or snapshots), so the plugin should use the
97 most efficient representation possible and not worry about serialisation
98 and portability.
99 */
100 LV2_STATE_IS_NATIVE = 1 << 2
101 } LV2_State_Flags;
102
103 /** A status code for state functions. */
104 typedef enum {
105 LV2_STATE_SUCCESS = 0, /**< Completed successfully. */
106 LV2_STATE_ERR_UNKNOWN = 1, /**< Unknown error. */
107 LV2_STATE_ERR_BAD_TYPE = 2, /**< Failed due to unsupported type. */
108 LV2_STATE_ERR_BAD_FLAGS = 3, /**< Failed due to unsupported flags. */
109 LV2_STATE_ERR_NO_FEATURE = 4, /**< Failed due to missing features. */
110 LV2_STATE_ERR_NO_PROPERTY = 5, /**< Failed due to missing property. */
111 LV2_STATE_ERR_NO_SPACE = 6 /**< Failed due to insufficient space. */
112 } LV2_State_Status;
113
114 /**
115 A host-provided function to store a property.
116 @param handle Must be the handle passed to LV2_State_Interface.save().
117 @param key The key to store `value` under (URID).
118 @param value Pointer to the value to be stored.
119 @param size The size of `value` in bytes.
120 @param type The type of `value` (URID).
121 @param flags LV2_State_Flags for `value`.
122 @return 0 on success, otherwise a non-zero error code.
123
124 The host passes a callback of this type to LV2_State_Interface.save(). This
125 callback is called repeatedly by the plugin to store all the properties that
126 describe its current state.
127
128 DO NOT INVENT NONSENSE URI SCHEMES FOR THE KEY. Best is to use keys from
129 existing vocabularies. If nothing appropriate is available, use http URIs
130 that point to somewhere you can host documents so documentation can be made
131 resolvable (typically a child of the plugin or project URI). If this is not
132 possible, invent a URN scheme, e.g. urn:myproj:whatever. The plugin MUST
133 NOT pass an invalid URI key.
134
135 The host MAY fail to store a property for whatever reason, but SHOULD
136 store any property that is LV2_STATE_IS_POD and LV2_STATE_IS_PORTABLE.
137 Implementations SHOULD use the types from the LV2 Atom extension
138 (http://lv2plug.in/ns/ext/atom) wherever possible. The plugin SHOULD
139 attempt to fall-back and avoid the error if possible.
140
141 Note that `size` MUST be > 0, and `value` MUST point to a valid region of
142 memory `size` bytes long (this is required to make restore unambiguous).
143
144 The plugin MUST NOT attempt to use this function outside of the
145 LV2_State_Interface.restore() context.
146 */
147 typedef LV2_State_Status (*LV2_State_Store_Function)(
148 LV2_State_Handle handle,
149 uint32_t key,
150 const void* value,
151 size_t size,
152 uint32_t type,
153 uint32_t flags);
154
155 /**
156 A host-provided function to retrieve a property.
157 @param handle Must be the handle passed to LV2_State_Interface.restore().
158 @param key The key of the property to retrieve (URID).
159 @param size (Output) If non-NULL, set to the size of the restored value.
160 @param type (Output) If non-NULL, set to the type of the restored value.
161 @param flags (Output) If non-NULL, set to the flags for the restored value.
162 @return A pointer to the restored value (object), or NULL if no value
163 has been stored under `key`.
164
165 A callback of this type is passed by the host to
166 LV2_State_Interface.restore(). This callback is called repeatedly by the
167 plugin to retrieve any properties it requires to restore its state.
168
169 The returned value MUST remain valid until LV2_State_Interface.restore()
170 returns. The plugin MUST NOT attempt to use this function, or any value
171 returned from it, outside of the LV2_State_Interface.restore() context.
172 */
173 typedef const void* (*LV2_State_Retrieve_Function)(
174 LV2_State_Handle handle,
175 uint32_t key,
176 size_t* size,
177 uint32_t* type,
178 uint32_t* flags);
179
180 /**
181 LV2 Plugin State Interface.
182
183 When the plugin's extension_data is called with argument
184 LV2_STATE__interface, the plugin MUST return an LV2_State_Interface
185 structure, which remains valid for the lifetime of the plugin.
186
187 The host can use the contained function pointers to save and restore the
188 state of a plugin instance at any time, provided the threading restrictions
189 of the functions are met.
190
191 Stored data is only guaranteed to be compatible between instances of plugins
192 with the same URI (i.e. if a change to a plugin would cause a fatal error
193 when restoring state saved by a previous version of that plugin, the plugin
194 URI MUST change just as it must when ports change incompatibly). Plugin
195 authors should consider this possibility, and always store sensible data
196 with meaningful types to avoid such problems in the future.
197 */
198 typedef struct {
199 /**
200 Save plugin state using a host-provided `store` callback.
201
202 @param instance The instance handle of the plugin.
203 @param store The host-provided store callback.
204 @param handle An opaque pointer to host data which MUST be passed as the
205 handle parameter to `store` if it is called.
206 @param flags Flags describing desired properties of this save. These
207 flags may be used to determine the most appropriate values to store.
208 @param features Extensible parameter for passing any additional
209 features to be used for this save.
210
211 The plugin is expected to store everything necessary to completely
212 restore its state later. Plugins SHOULD store simple POD data whenever
213 possible, and consider the possibility of state being restored much
214 later on a different machine.
215
216 The `handle` pointer and `store` function MUST NOT be used
217 beyond the scope of save().
218
219 This function has its own special threading class: it may not be called
220 concurrently with any "Instantiation" function, but it may be called
221 concurrently with functions in any other class, unless the definition of
222 that class prohibits it (for example, it may not be called concurrently
223 with a "Discovery" function, but it may be called concurrently with an
224 "Audio" function. The plugin is responsible for any locking or
225 lock-free techniques necessary to make this possible.
226
227 Note that in the simple case where state is only modified by restore(),
228 there are no synchronization issues since save() is never called
229 concurrently with restore() (though run() may read it during a save).
230
231 Plugins that dynamically modify state while running, however, must take
232 care to do so in such a way that a concurrent call to save() will save a
233 consistent representation of plugin state for a single instant in time.
234 */
235 LV2_State_Status (*save)(LV2_Handle instance,
236 LV2_State_Store_Function store,
237 LV2_State_Handle handle,
238 uint32_t flags,
239 const LV2_Feature *const * features);
240
241 /**
242 Restore plugin state using a host-provided `retrieve` callback.
243
244 @param instance The instance handle of the plugin.
245 @param retrieve The host-provided retrieve callback.
246 @param handle An opaque pointer to host data which MUST be passed as the
247 handle parameter to `retrieve` if it is called.
248 @param flags Currently unused.
249 @param features Extensible parameter for passing any additional
250 features to be used for this restore.
251
252 The plugin MAY assume a restored value was set by a previous call to
253 LV2_State_Interface.save() by a plugin with the same URI.
254
255 The plugin MUST gracefully fall back to a default value when a value can
256 not be retrieved. This allows the host to reset the plugin state with
257 an empty map.
258
259 The `handle` pointer and `store` function MUST NOT be used
260 beyond the scope of restore().
261
262 This function is in the "Instantiation" threading class as defined by
263 LV2. This means it MUST NOT be called concurrently with any other
264 function on the same plugin instance.
265 */
266 LV2_State_Status (*restore)(LV2_Handle instance,
267 LV2_State_Retrieve_Function retrieve,
268 LV2_State_Handle handle,
269 uint32_t flags,
270 const LV2_Feature *const * features);
271 } LV2_State_Interface;
272
273 /**
274 Feature data for state:mapPath (@ref LV2_STATE__mapPath).
275 */
276 typedef struct {
277 /**
278 Opaque host data.
279 */
280 LV2_State_Map_Path_Handle handle;
281
282 /**
283 Map an absolute path to an abstract path for use in plugin state.
284 @param handle MUST be the `handle` member of this struct.
285 @param absolute_path The absolute path of a file.
286 @return An abstract path suitable for use in plugin state.
287
288 The plugin MUST use this function to map any paths that will be stored
289 in plugin state. The returned value is an abstract path which MAY not
290 be an actual file system path; absolute_path() MUST be used to map
291 it to an actual path in order to use the file.
292
293 Plugins MUST NOT make any assumptions about abstract paths except that
294 they can be mapped back to the absolute path of the "same" file (though
295 not necessarily the same original path) using absolute_path().
296
297 This function may only be called within the context of
298 LV2_State_Interface methods. The caller must free the returned value
299 with LV2_State_Free_Path.free_path().
300 */
301 char* (*abstract_path)(LV2_State_Map_Path_Handle handle,
302 const char* absolute_path);
303
304 /**
305 Map an abstract path from plugin state to an absolute path.
306 @param handle MUST be the `handle` member of this struct.
307 @param abstract_path An abstract path (typically from plugin state).
308 @return An absolute file system path.
309
310 The plugin MUST use this function in order to actually open or otherwise
311 use any paths loaded from plugin state.
312
313 This function may only be called within the context of
314 LV2_State_Interface methods. The caller must free the returned value
315 with LV2_State_Free_Path.free_path().
316 */
317 char* (*absolute_path)(LV2_State_Map_Path_Handle handle,
318 const char* abstract_path);
319 } LV2_State_Map_Path;
320
321 /**
322 Feature data for state:makePath (@ref LV2_STATE__makePath).
323 */
324 typedef struct {
325 /**
326 Opaque host data.
327 */
328 LV2_State_Make_Path_Handle handle;
329
330 /**
331 Return a path the plugin may use to create a new file.
332 @param handle MUST be the `handle` member of this struct.
333 @param path The path of the new file within a namespace unique to this
334 plugin instance.
335 @return The absolute path to use for the new file.
336
337 This function can be used by plugins to create files and directories,
338 either at state saving time (if this feature is passed to
339 LV2_State_Interface.save()) or any time (if this feature is passed to
340 LV2_Descriptor.instantiate()).
341
342 The host MUST do whatever is necessary for the plugin to be able to
343 create a file at the returned path (for example, using fopen()),
344 including creating any leading directories.
345
346 If this function is passed to LV2_Descriptor.instantiate(), it may be
347 called from any non-realtime context. If it is passed to
348 LV2_State_Interface.save(), it may only be called within the dynamic
349 scope of that function call.
350
351 The caller must free the returned value with
352 LV2_State_Free_Path.free_path().
353 */
354 char* (*path)(LV2_State_Make_Path_Handle handle,
355 const char* path);
356 } LV2_State_Make_Path;
357
358 /**
359 Feature data for state:freePath (@ref LV2_STATE__freePath).
360 */
361 typedef struct {
362 /**
363 Opaque host data.
364 */
365 LV2_State_Free_Path_Handle handle;
366
367 /**
368 Free a path returned by a state feature.
369
370 @param handle MUST be the `handle` member of this struct.
371 @param path The path previously returned by a state feature.
372
373 This function can be used by plugins to free paths allocated by the host
374 and returned by state features (LV2_State_Map_Path.abstract_path(),
375 LV2_State_Map_Path.absolute_path(), and LV2_State_Make_Path.path()).
376 */
377 void (*free_path)(LV2_State_Free_Path_Handle handle,
378 char* path);
379 } LV2_State_Free_Path;
380
381 #ifdef __cplusplus
382 } /* extern "C" */
383 #endif
384
385 #endif /* LV2_STATE_H */
386
387 /**
388 @}
389 */