/* lv2_atom_helpers.h - Helper functions for the LV2 atoms extension. * Copyright (C) 2008-2010 David Robillard * * This header is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published * by the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This header is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this header; if not, write to the Free Software Foundation, * Inc., 59 Temple Place, Suite 330, Boston, MA 01222-1307 USA */ #ifndef LV2_ATOM_HELPERS_H #define LV2_ATOM_HELPERS_H #include #include #include #include "lv2/http/lv2plug.in/ns/ext/atom/atom.h" /** @file * Helper functions for the LV2 Atom extension * . * * These functions are provided for convenience only, use of them is not * required for supporting atoms (i.e. the definition of atoms in memory * is described in atom.h and NOT by this API). * * Note that these functions are all static inline which basically means: * do not take the address of these functions. */ /** Pad a size to 4 bytes (32 bits) */ static inline uint16_t lv2_atom_pad_size(uint16_t size) { return (size + 3) & (~3); } typedef LV2_Atom_Property* LV2_Object_Iter; /** Get an iterator pointing to @a prop in some LV2_Object */ static inline LV2_Object_Iter lv2_object_begin(LV2_Atom* obj) { return (LV2_Object_Iter)(((LV2_Object*)obj->body)->properties); } /** Return true iff @a iter has reached the end of @a object */ static inline bool lv2_object_iter_is_end(const LV2_Atom* object, LV2_Object_Iter iter) { return (uint8_t*)iter >= (object->body + object->size); } /** Return true iff @a l points to the same property as @a r */ static inline bool lv2_object_iter_equals(const LV2_Object_Iter l, const LV2_Object_Iter r) { return l == r; } /** Return an iterator to the property following @a iter */ static inline LV2_Object_Iter lv2_object_iter_next(const LV2_Object_Iter iter) { return (LV2_Object_Iter)( (uint8_t*)iter + sizeof(LV2_Atom_Property) + lv2_atom_pad_size(iter->value.size)); } /** Return the property pointed to by @a iter */ static inline LV2_Atom_Property* lv2_object_iter_get(LV2_Object_Iter iter) { return (LV2_Atom_Property*)iter; } /** A macro for iterating over all properties of an Object. * @param obj The object to iterate over * @param iter The name of the iterator * This macro is used similarly to a for loop (which it expands to), e.g.: *
 * LV2_OBJECT_FOREACH(object, i) {
 *    LV2_Atom_Property* prop = lv2_object_iter_get(i);
 *    // Do things with prop here...
 * }
 * 
*/ #define LV2_OBJECT_FOREACH(obj, iter) \ for (LV2_Object_Iter (iter) = lv2_object_begin(obj); \ !lv2_object_iter_is_end(obj, (iter)); \ (iter) = lv2_object_iter_next(iter)) /** Append a Property body to an Atom that contains properties (e.g. atom:Object). * This function will write the property body (not including an LV2_Object * header) at lv2_atom_pad_size(body + size). Thus, it can be used with any * Atom type that contains headerless 32-bit aligned properties. * @param object Pointer to the atom that contains the property to add. object.size * must be valid, but object.type is ignored. * @param key The key of the new property * @param value_type The type of the new value * @param value_size The size of the new value * @param value_body Pointer to the new value's data * @return a pointer to the new LV2_Atom_Property in @a body. */ static inline LV2_Atom_Property* lv2_atom_append_property(LV2_Atom* object, uint32_t key, uint16_t value_type, uint16_t value_size, const uint8_t* value_body) { object->size = lv2_atom_pad_size(object->size); LV2_Atom_Property* prop = (LV2_Atom_Property*)(object->body + object->size); prop->key = key; prop->value.type = value_type; prop->value.size = value_size; memcpy(prop->value.body, value_body, value_size); object->size += sizeof(uint32_t) + sizeof(LV2_Atom_Property) + value_size; return prop; } /** Return true iff @a atom is NULL */ static inline bool lv2_atom_is_null(LV2_Atom* atom) { return !atom || (atom->type == 0 && atom->size == 0); } /** Return true iff @a object has rdf:type @a type */ static inline bool lv2_atom_is_a(LV2_Atom* object, uint32_t rdf_type, uint32_t atom_URIInt, uint32_t atom_Object, uint32_t type) { if (lv2_atom_is_null(object)) return false; if (object->type == type) return true; if (object->type == atom_Object) { LV2_OBJECT_FOREACH(object, o) { LV2_Atom_Property* prop = lv2_object_iter_get(o); if (prop->key == rdf_type) { if (prop->value.type == atom_URIInt) { const uint32_t object_type = *(uint32_t*)prop->value.body; if (object_type == type) return true; } else { fprintf(stderr, "error: rdf:type is not a URIInt\n"); } } } } return false; } /** A single entry in an Object query. */ typedef struct { uint32_t key; ///< Set by the user to the desired key to query. LV2_Atom* value; ///< Possibly set by query function to the found value } LV2_Object_Query; /** "Query" an object, getting a pointer to the values for various keys. * The value pointer of each item in @a q will be set to the location of * the corresponding value in @a object. Every value pointer in @a query * MUST be initialised to NULL. This function reads @a object in a single * linear sweep. By allocating @a q on the stack, objects can be "queried" * quickly without allocating any memory. This function is realtime safe. */ static inline int lv2_object_query(LV2_Atom* object, LV2_Object_Query* query) { int matches = 0; int n_queries = 0; // Count number of query keys so we can short-circuit when done for (LV2_Object_Query* q = query; q->key; ++q) ++n_queries; LV2_OBJECT_FOREACH(object, o) { LV2_Atom_Property* prop = lv2_object_iter_get(o); for (LV2_Object_Query* q = query; q->key; ++q) { if (q->key == prop->key && !q->value) { q->value = &prop->value; if (++matches == n_queries) return matches; break; } } } return matches; } #endif /* LV2_ATOM_HELPERS_H */