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+/*
+ Copyright 2008-2011 David Robillard <http://drobilla.net>
+
+ Permission to use, copy, modify, and/or distribute this software for any
+ purpose with or without fee is hereby granted, provided that the above
+ copyright notice and this permission notice appear in all copies.
+
+ THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+/**
+ @file atom-helpers.h Helper functions for the LV2 Atom extension.
+
+ These functions are provided for convenience only, use of them is not
+ required for supporting atoms.
+
+ Note that these functions are all static inline which basically means:
+ do not take the address of these functions.
+*/
+
+#ifndef LV2_ATOM_HELPERS_H
+#define LV2_ATOM_HELPERS_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "lv2/lv2plug.in/ns/ext/atom/atom.h"
+
+typedef LV2_Atom_Property* LV2_Thing_Iter;
+
+/** Get an iterator pointing to @c prop in some LV2_Thing */
+static inline LV2_Thing_Iter
+lv2_thing_begin(const LV2_Thing* obj)
+{
+ return (LV2_Thing_Iter)(obj->properties);
+}
+
+/** Return true iff @c iter has reached the end of @c thing */
+static inline bool
+lv2_thing_iter_is_end(const LV2_Thing* obj, LV2_Thing_Iter iter)
+{
+ return (uint8_t*)iter >= ((uint8_t*)obj + sizeof(LV2_Atom) + obj->size);
+}
+
+/** Return true iff @c l points to the same property as @c r */
+static inline bool
+lv2_thing_iter_equals(const LV2_Thing_Iter l, const LV2_Thing_Iter r)
+{
+ return l == r;
+}
+
+/** Return an iterator to the property following @c iter */
+static inline LV2_Thing_Iter
+lv2_thing_iter_next(const LV2_Thing_Iter iter)
+{
+ return (LV2_Thing_Iter)((uint8_t*)iter
+ + sizeof(LV2_Atom_Property)
+ + lv2_atom_pad_size(iter->value.size));
+}
+
+/** Return the property pointed to by @c iter */
+static inline LV2_Atom_Property*
+lv2_thing_iter_get(LV2_Thing_Iter iter)
+{
+ return (LV2_Atom_Property*)iter;
+}
+
+/**
+ A macro for iterating over all properties of an Thing.
+ @param thing The thing 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.:
+ <pre>
+ LV2_THING_FOREACH(thing, i) {
+ LV2_Atom_Property* prop = lv2_thing_iter_get(i);
+ // Do things with prop here...
+ }
+ </pre>
+*/
+#define LV2_THING_FOREACH(thing, iter) \
+ for (LV2_Thing_Iter (iter) = lv2_thing_begin(thing); \
+ !lv2_thing_iter_is_end(thing, (iter)); \
+ (iter) = lv2_thing_iter_next(iter))
+
+/**
+ Append a Property body to an Atom that contains properties (e.g. atom:Thing).
+ @param thing Pointer to the atom that contains the property to add. thing.size
+ must be valid, but thing.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 @c body.
+
+ This function will write the property body (not including an LV2_Thing
+ header) at lv2_atom_pad_size(body + size). Thus, it can be used with any
+ Atom type that contains headerless 32-bit aligned properties.
+*/
+static inline LV2_Atom_Property*
+lv2_thing_append(LV2_Thing* thing,
+ uint32_t key,
+ uint32_t value_type,
+ uint32_t value_size,
+ const void* value_body)
+{
+ thing->size = lv2_atom_pad_size(thing->size);
+ LV2_Atom_Property* prop = (LV2_Atom_Property*)(
+ (uint8_t*)thing + sizeof(LV2_Atom) + thing->size);
+ prop->key = key;
+ prop->value.type = value_type;
+ prop->value.size = value_size;
+ memcpy(prop->value.body, value_body, value_size);
+ thing->size += sizeof(LV2_Atom_Property) + value_size;
+ return prop;
+}
+
+/** Return true iff @c atom is NULL */
+static inline bool
+lv2_atom_is_null(LV2_Atom* atom)
+{
+ return !atom || (atom->type == 0 && atom->size == 0);
+}
+
+/** A single entry in an Thing query. */
+typedef struct {
+ uint32_t key; /**< Key to query (input set by user) */
+ const LV2_Atom** value; /**< Found value (output set by query function) */
+} LV2_Thing_Query;
+
+static const LV2_Thing_Query LV2_THING_QUERY_END = { 0, NULL };
+
+/**
+ "Query" an thing, getting a pointer to the values for various keys.
+
+ The value pointer of each item in @c query will be set to the location of
+ the corresponding value in @c thing. Every value pointer in @c query MUST
+ be initialised to NULL. This function reads @c thing in a single linear
+ sweep. By allocating @c query on the stack, things can be "queried"
+ quickly without allocating any memory. This function is realtime safe.
+*/
+static inline int
+lv2_thing_query(const LV2_Thing* thing, LV2_Thing_Query* query)
+{
+ int matches = 0;
+ int n_queries = 0;
+
+ /* Count number of query keys so we can short-circuit when done */
+ for (LV2_Thing_Query* q = query; q->key; ++q)
+ ++n_queries;
+
+ LV2_THING_FOREACH(thing, o) {
+ const LV2_Atom_Property* prop = lv2_thing_iter_get(o);
+ for (LV2_Thing_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 */