1 /*
2 Copyright 2010-2016 David Robillard <http://drobilla.net>
3 Copyright 2010 Leonard Ritter <paniq@paniq.org>
4 Copyright 2018 Ethan Reker <http://cutthroughrecordings.com>
5 6 Permission to use, copy, modify, and/or distribute this software for any
7 purpose with or without fee is hereby granted, provided that the above
8 copyright notice and this permission notice appear in all copies.
9 10 THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */18 19 /**
20 @defgroup state State
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 moduledplug.lv2.state;
28 29 version(LV2):
30 31 nothrow @nogc:
32 33 importcore.stdc.stddef;
34 importcore.stdc.stdint;
35 36 importdplug.lv2.lv2;
37 38 enumLV2_STATE_URI = "http://lv2plug.in/ns/ext/state"; ///< http://lv2plug.in/ns/ext/state39 enumLV2_STATE_PREFIX = LV2_STATE_URI ~ "#"; ///< http://lv2plug.in/ns/ext/state#40 41 enumLV2_STATE__State = LV2_STATE_PREFIX ~ "State"; ///< http://lv2plug.in/ns/ext/state#State42 enumLV2_STATE__interface = LV2_STATE_PREFIX ~ "interface"; ///< http://lv2plug.in/ns/ext/state#interface43 enumLV2_STATE__loadDefaultState = LV2_STATE_PREFIX ~ "loadDefaultState"; ///< http://lv2plug.in/ns/ext/state#loadDefaultState44 enumLV2_STATE__makePath = LV2_STATE_PREFIX ~ "makePath"; ///< http://lv2plug.in/ns/ext/state#makePath45 enumLV2_STATE__mapPath = LV2_STATE_PREFIX ~ "mapPath"; ///< http://lv2plug.in/ns/ext/state#mapPath46 enumLV2_STATE__state = LV2_STATE_PREFIX ~ "state"; ///< http://lv2plug.in/ns/ext/state#state47 enumLV2_STATE__threadSafeRestore = LV2_STATE_PREFIX ~ "threadSafeRestore"; ///< http://lv2plug.in/ns/ext/state#threadSafeRestore48 49 aliasLV2_State_Handle = void*; ///b< Opaque handle for state save/restore50 aliasLV2_State_Map_Path_Handle = void*; ///< Opaque handle for state:mapPath feature51 aliasLV2_State_Make_Path_Handle = void*; ///< Opaque handle for state:makePath feature52 53 /**
54 Flags describing value characteristics.
55 56 These flags are used along with the value's type URI to determine how to
57 (de-)serialise the value data, or whether it is even possible to do so.
58 */59 aliasLV2_State_Flags = int;
60 enum : LV2_State_Flags {
61 /**
62 Plain Old Data.
63 64 Values with this flag contain no pointers or references to other areas
65 of memory. It is safe to copy POD values with a simple memcpy and store
66 them for the duration of the process. A POD value is not necessarily
67 safe to transmit between processes or machines (e.g. filenames are POD),
68 see LV2_STATE_IS_PORTABLE for details.
69 70 Implementations MUST NOT attempt to copy or serialise a non-POD value if
71 they do not understand its type (and thus know how to correctly do so).
72 */73 LV2_STATE_IS_POD = 1,
74 75 /**
76 Portable (architecture independent) data.
77 78 Values with this flag are in a format that is usable on any
79 architecture. A portable value saved on one machine can be restored on
80 another machine regardless of architecture. The format of portable
81 values MUST NOT depend on architecture-specific properties like
82 endianness or alignment. Portable values MUST NOT contain filenames.
83 */84 LV2_STATE_IS_PORTABLE = 1 << 1,
85 86 /**
87 Native data.
88 89 This flag is used by the host to indicate that the saved data is only
90 going to be used locally in the currently running process (e.g. for
91 instance duplication or snapshots), so the plugin should use the most
92 efficient representation possible and not worry about serialisation
93 and portability.
94 */95 LV2_STATE_IS_NATIVE = 1 << 296 }
97 98 /** A status code for state functions. */99 aliasLV2_State_Status = int;
100 enum : int {
101 LV2_STATE_SUCCESS = 0, /**< Completed successfully. */102 LV2_STATE_ERR_UNKNOWN = 1, /**< Unknown error. */103 LV2_STATE_ERR_BAD_TYPE = 2, /**< Failed due to unsupported type. */104 LV2_STATE_ERR_BAD_FLAGS = 3, /**< Failed due to unsupported flags. */105 LV2_STATE_ERR_NO_FEATURE = 4, /**< Failed due to missing features. */106 LV2_STATE_ERR_NO_PROPERTY = 5, /**< Failed due to missing property. */107 LV2_STATE_ERR_NO_SPACE = 6/**< Failed due to insufficient space. */108 }
109 110 /**
111 A host-provided function to store a property.
112 @param handle Must be the handle passed to LV2_State_Interface.save().
113 @param key The key to store `value` under (URID).
114 @param value Pointer to the value to be stored.
115 @param size The size of `value` in bytes.
116 @param type The type of `value` (URID).
117 @param flags LV2_State_Flags for `value`.
118 @return 0 on success, otherwise a non-zero error code.
119 120 The host passes a callback of this type to LV2_State_Interface.save(). This
121 callback is called repeatedly by the plugin to store all the properties that
122 describe its current state.
123 124 DO NOT INVENT NONSENSE URI SCHEMES FOR THE KEY. Best is to use keys from
125 existing vocabularies. If nothing appropriate is available, use http URIs
126 that point to somewhere you can host documents so documentation can be made
127 resolvable (e.g. a child of the plugin or project URI). If this is not
128 possible, invent a URN scheme, e.g. urn:myproj:whatever. The plugin MUST
129 NOT pass an invalid URI key.
130 131 The host MAY fail to store a property for whatever reason, but SHOULD
132 store any property that is LV2_STATE_IS_POD and LV2_STATE_IS_PORTABLE.
133 Implementations SHOULD use the types from the LV2 Atom extension
134 (http://lv2plug.in/ns/ext/atom) wherever possible. The plugin SHOULD
135 attempt to fall-back and avoid the error if possible.
136 137 Note that `size` MUST be > 0, and `value` MUST point to a valid region of
138 memory `size` bytes long (this is required to make restore unambiguous).
139 140 The plugin MUST NOT attempt to use this function outside of the
141 LV2_State_Interface.restore() context.
142 */143 extern(C)
144 {
145 aliasLV2_State_Store_Function = LV2_State_Statusfunction(LV2_State_Handlehandle, uintkey, const(void)* value, size_tsize, uinttype, uintflags);
146 }
147 148 /**
149 A host-provided function to retrieve a property.
150 @param handle Must be the handle passed to LV2_State_Interface.restore().
151 @param key The key of the property to retrieve (URID).
152 @param size (Output) If non-NULL, set to the size of the restored value.
153 @param type (Output) If non-NULL, set to the type of the restored value.
154 @param flags (Output) If non-NULL, set to the flags for the restored value.
155 @return A pointer to the restored value (object), or NULL if no value
156 has been stored under `key`.
157 158 A callback of this type is passed by the host to
159 LV2_State_Interface.restore(). This callback is called repeatedly by the
160 plugin to retrieve any properties it requires to restore its state.
161 162 The returned value MUST remain valid until LV2_State_Interface.restore()
163 returns. The plugin MUST NOT attempt to use this function, or any value
164 returned from it, outside of the LV2_State_Interface.restore() context.
165 */166 extern(C)
167 {
168 aliasLV2_State_Retrieve_Function = const(void)* function(LV2_State_Handlehandle, uintkey, size_t* size, uint* type, uint* flags);
169 }
170 171 /**
172 LV2 Plugin State Interface.
173 174 When the plugin's extension_data is called with argument
175 LV2_STATE__interface, the plugin MUST return an LV2_State_Interface
176 structure, which remains valid for the lifetime of the plugin.
177 178 The host can use the contained function pointers to save and restore the
179 state of a plugin instance at any time, provided the threading restrictions
180 of the functions are met.
181 182 Stored data is only guaranteed to be compatible between instances of plugins
183 with the same URI (i.e. if a change to a plugin would cause a fatal error
184 when restoring state saved by a previous version of that plugin, the plugin
185 URI MUST change just as it must when ports change incompatibly). Plugin
186 authors should consider this possibility, and always store sensible data
187 with meaningful types to avoid such problems in the future.
188 */189 structLV2_State_Interface190 {
191 nothrow @nogc:
192 /**
193 Save plugin state using a host-provided `store` callback.
194 195 @param instance The instance handle of the plugin.
196 @param store The host-provided store callback.
197 @param handle An opaque pointer to host data which MUST be passed as the
198 handle parameter to `store` if it is called.
199 @param flags Flags describing desired properties of this save. These
200 flags may be used to determine the most appropriate values to store.
201 @param features Extensible parameter for passing any additional
202 features to be used for this save.
203 204 The plugin is expected to store everything necessary to completely
205 restore its state later. Plugins SHOULD store simple POD data whenever
206 possible, and consider the possibility of state being restored much
207 later on a different machine.
208 209 The `handle` pointer and `store` function MUST NOT be used
210 beyond the scope of save().
211 212 This function has its own special threading class: it may not be called
213 concurrently with any "Instantiation" function, but it may be called
214 concurrently with functions in any other class, unless the definition of
215 that class prohibits it (e.g. it may not be called concurrently with a
216 "Discovery" function, but it may be called concurrently with an "Audio"
217 function. The plugin is responsible for any locking or lock-free
218 techniques necessary to make this possible.
219 220 Note that in the simple case where state is only modified by restore(),
221 there are no synchronization issues since save() is never called
222 concurrently with restore() (though run() may read it during a save).
223 224 Plugins that dynamically modify state while running, however, must take
225 care to do so in such a way that a concurrent call to save() will save a
226 consistent representation of plugin state for a single instant in time.
227 */228 extern(C)
229 {
230 aliassaveFun_t = LV2_State_Statusfunction(LV2_Handleinstance,
231 LV2_State_Store_Functionstore,
232 LV2_State_Handlehandle,
233 uintflags,
234 const(LV2_Feature*)* features);
235 }
236 saveFun_tsave;
237 238 /**
239 Restore plugin state using a host-provided `retrieve` callback.
240 241 @param instance The instance handle of the plugin.
242 @param retrieve The host-provided retrieve callback.
243 @param handle An opaque pointer to host data which MUST be passed as the
244 handle parameter to `retrieve` if it is called.
245 @param flags Currently unused.
246 @param features Extensible parameter for passing any additional
247 features to be used for this restore.
248 249 The plugin MAY assume a restored value was set by a previous call to
250 LV2_State_Interface.save() by a plugin with the same URI.
251 252 The plugin MUST gracefully fall back to a default value when a value can
253 not be retrieved. This allows the host to reset the plugin state with
254 an empty map.
255 256 The `handle` pointer and `store` function MUST NOT be used
257 beyond the scope of restore().
258 259 This function is in the "Instantiation" threading class as defined by
260 LV2. This means it MUST NOT be called concurrently with any other
261 function on the same plugin instance.
262 */263 extern(C)
264 {
265 aliasrestoreFun_t = LV2_State_Statusfunction(LV2_Handleinstance,
266 LV2_State_Retrieve_Functionretrieve,
267 LV2_State_Handlehandle,
268 uintflags,
269 const(LV2_Feature*)* features);
270 }
271 restoreFun_trestore;
272 273 };