Add atom-helpers.h.

1 files changed, 109 insertions, 0 deletions

diff --git a/ext/atom.lv2/atom-helpers.h b/ext/atom.lv2/atom-helpers.h
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+++ b/ext/atom.lv2/atom-helpers.h
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+/* lv2_atom_helpers.h - Helper functions for the LV2 atoms extension.
+ * Copyright (C) 2008-2010 David Robillard <http://drobilla.net>
+ *
+ * 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 <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include "lv2/http/lv2plug.in/ns/ext/atom/atom.h"
+
+/** @file
+ * Helper functions for the LV2 Atom extension
+ * <http://lv2plug.in/ns/ext/atom>.
+ *
+ * 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 64 bits (for atom sizes) */
+static inline uint16_t
+lv2_atom_pad_size(uint16_t size)
+{
+	return (size + 7) & (~7);
+}
+
+typedef LV2_Atom_Property* LV2_Atom_Dict_Iter;
+
+static inline LV2_Atom_Dict_Iter
+lv2_atom_dict_get_iter(LV2_Atom_Property* prop)
+{
+	return (LV2_Atom_Dict_Iter)prop;
+}
+
+static inline bool
+lv2_atom_dict_iter_is_end(LV2_Atom* dict, LV2_Atom_Dict_Iter iter)
+{
+	return (uint8_t*)iter >= (dict->body + dict->size);
+}
+
+static inline bool
+lv2_atom_dict_iter_equals(const LV2_Atom_Dict_Iter l, const LV2_Atom_Dict_Iter r)
+{
+	return l == r;
+}
+
+static inline LV2_Atom_Dict_Iter
+lv2_atom_dict_iter_next(const LV2_Atom_Dict_Iter iter)
+{
+	return (LV2_Atom_Dict_Iter)(
+		(uint8_t*)iter + sizeof(LV2_Atom_Property) + lv2_atom_pad_size(iter->object.size));
+}
+
+static inline LV2_Atom_Property*
+lv2_atom_dict_iter_get(LV2_Atom_Dict_Iter iter)
+{
+	return (LV2_Atom_Property*)iter;
+}
+
+/** Append a Property body to an Atom that contains properties (e.g. atom:Dict).
+ * 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 64-bit aligned properties.
+ * @param dict Pointer to the atom that contains the property to add.  dict.size
+ *        must be valid, but dict.type is ignored.
+ * @param size Must point to the size field of the container atom, and will be
+ *        padded up to 64 bits then increased by @a value_size.
+ * @param body Must point to the body of the container atom.
+ * @return a pointer to the new LV2_Atom_Property in @a body.
+ */
+static inline LV2_Atom_Property*
+lv2_atom_append_property(LV2_Atom*   dict,
+                         uint32_t    key,
+                         uint16_t    value_type,
+                         uint16_t    value_size,
+                         const char* value_body)
+{
+	dict->size = lv2_atom_pad_size(dict->size);
+	LV2_Atom_Property* prop = (LV2_Atom_Property*)(dict->body + dict->size);
+	prop->predicate = key;
+	prop->object.type = value_type;
+	prop->object.size = value_size;
+	memcpy(prop->object.body, value_body, value_size);
+	dict->size += sizeof(uint32_t) + sizeof(LV2_Atom_Property) + value_size;
+	return prop;
+}
+
+#endif /* LV2_ATOM_HELPERS_H */
+