Add lv2_atom_sequence_clear() and lv2_atom_sequence_append_event() helper functions.

Add MIDI fifths example plugin for simple non-forge MIDI reading and writing.

2 files changed, 48 insertions, 0 deletions

diff --git a/lv2/lv2plug.in/ns/ext/atom/lv2-atom.doap.ttl b/lv2/lv2plug.in/ns/ext/atom/lv2-atom.doap.ttl
index 251d998..f70a410 100644
--- a/lv2/lv2plug.in/ns/ext/atom/lv2-atom.doap.ttl
+++ b/lv2/lv2plug.in/ns/ext/atom/lv2-atom.doap.ttl
@@ -22,6 +22,8 @@
 				rdfs:label "Add lv2_atom_forge_is_object_type() and lv2_atom_forge_is_blank() to ease backwards compatibility."
 			] , [
 				rdfs:label "Add lv2_atom_forge_key() for terser object writing."
+			] , [
+				rdfs:label "Add lv2_atom_sequence_clear() and lv2_atom_sequence_append_event() helper functions."
 			]
 		]
 	] , [
diff --git a/lv2/lv2plug.in/ns/ext/atom/util.h b/lv2/lv2plug.in/ns/ext/atom/util.h
index d306e1c..d7c020b 100644
--- a/lv2/lv2plug.in/ns/ext/atom/util.h
+++ b/lv2/lv2plug.in/ns/ext/atom/util.h
@@ -129,6 +129,52 @@ lv2_atom_sequence_next(const LV2_Atom_Event* i)
 
 /**
    @}
+   @name Sequence Utilities
+   @{
+*/
+
+/**
+   Clear all events from @p sequence.
+
+   This simply resets the size field, the other fields are left untouched.
+*/
+static inline void
+lv2_atom_sequence_clear(LV2_Atom_Sequence* seq)
+{
+	seq->atom.size = sizeof(LV2_Atom_Sequence_Body);
+}
+
+/**
+   Append an event at the end of @p sequence.
+
+   @param seq Sequence to append to.
+   @param capacity Total capacity of the sequence atom
+   (e.g. as set by the host for sequence output ports).
+   @param event Event to write.
+
+   @return A pointer to the newly written event in @p seq,
+   or NULL on failure (insufficient space).
+*/
+static inline LV2_Atom_Event*
+lv2_atom_sequence_append_event(LV2_Atom_Sequence*    seq,
+                               uint32_t              capacity,
+                               const LV2_Atom_Event* event)
+{
+	const uint32_t total_size = (uint32_t)sizeof(*event) + event->body.size;
+	if (capacity - seq->atom.size < total_size) {
+		return NULL;
+	}
+
+	LV2_Atom_Event* e = lv2_atom_sequence_end(&seq->body, seq->atom.size);
+	memcpy(e, event, total_size);
+
+	seq->atom.size += lv2_atom_pad_size(total_size);
+
+	return e;
+}
+
+/**
+   @}
    @name Tuple Iterator
    @{
 */