Simplify atom:AtomPort buffers to point directly at Atoms.

4 files changed, 45 insertions, 61 deletions

diff --git a/lv2/lv2plug.in/ns/ext/atom/atom.h b/lv2/lv2plug.in/ns/ext/atom/atom.h
index 9bce7ce..2eed233 100644
--- a/lv2/lv2plug.in/ns/ext/atom/atom.h
+++ b/lv2/lv2plug.in/ns/ext/atom/atom.h
@@ -33,6 +33,7 @@
 #define LV2_ATOM__Beats         LV2_ATOM_URI "#Beats"
 #define LV2_ATOM__Blank         LV2_ATOM_URI "#Blank"
 #define LV2_ATOM__Bool          LV2_ATOM_URI "#Bool"
+#define LV2_ATOM__Chunk         LV2_ATOM_URI "#Chunk"
 #define LV2_ATOM__Double        LV2_ATOM_URI "#Double"
 #define LV2_ATOM__Event         LV2_ATOM_URI "#Event"
 #define LV2_ATOM__Float         LV2_ATOM_URI "#Float"
@@ -225,33 +226,10 @@ typedef struct {
 
 /** An atom:Sequence. */
 typedef struct {
-	LV2_Atom              atom;  /**< Atom header. */
-	LV2_Atom_Literal_Body body;  /**< Body. */
+	LV2_Atom               atom;  /**< Atom header. */
+	LV2_Atom_Sequence_Body body;  /**< Body. */
 } LV2_Atom_Sequence;
 
-/**
-   The contents of an atom:AtomPort buffer.
-
-   This contains a pointer to an Atom, which is the data to be
-   processed/written, as well as additional metadata.  This struct may be
-   augmented in the future to add more metadata fields as they become
-   necessary.  The initial version of this struct contains data, size, and
-   capacity.  Implementations MUST check that any other fields they wish to use
-   are actually present by comparing the size with the offset of that field,
-   e.g.:
-
-   @code
-   if (offsetof(LV2_Atom_Port_Buffer, field) < buf->size) {
-       do_stuff_with(buf->field);
-   }
-   @endcode
-*/
-typedef struct {
-	LV2_Atom* data;      /** Pointer to data. */
-	uint32_t  size;      /** Total size of this struct. */
-	uint32_t  capacity;  /** Available space for data body. */
-} LV2_Atom_Port_Buffer;
-
 #ifdef __cplusplus
 }  /* extern "C" */
 #endif
diff --git a/lv2/lv2plug.in/ns/ext/atom/atom.ttl b/lv2/lv2plug.in/ns/ext/atom/atom.ttl
index b939f33..1a2b92a 100644
--- a/lv2/lv2plug.in/ns/ext/atom/atom.ttl
+++ b/lv2/lv2plug.in/ns/ext/atom/atom.ttl
@@ -109,6 +109,17 @@ atom with both <code>type</code> <em>and</em> <code>size</code> 0 is
 <q>null</q>, which is not considered a Reference.</p>
 """ .
 
+atom:Chunk
+	a rdfs:Class ;
+	rdfs:subClassOf atom:Atom ;
+	rdfs:label "Chunk of memory" ;
+	lv2:documentation """
+<p>A chunk of memory with undefined contents.  This type is used to indicate a
+certain amount of space is available.  For example, output ports with a
+variably sized type are connected to a Chunk so the plugin knows the size of
+the buffer available for writing.</p>
+""" .
+
 atom:Number
 	a rdfs:Class ;
 	rdfs:subClassOf atom:Atom ;
@@ -405,24 +416,16 @@ atom:AtomPort
 	rdfs:label "Atom Port" ;
 	lv2:documentation """
 <p>A port which contains an lv2:Atom.  Ports of this type are connected to an
-LV2_Atom_Port_Buffer, which contains a pointer to the port's Atom contents, as
-well as other metadata (such as capacity, for output ports with variably sized
-types).  The host MUST set all fields of LV2_Atom_Port_Buffer to appropriate
-values before calling the plugin's run method.  LV2_Atom_Port_Buffer::capacity
-must be set to the available space for the <em>body</em> of LV2_Atom_Port_Buffer::data,
-i.e. the maximum possible value for its <code>size</code> field, which does
-not include the LV2_Atom header.</p>
+LV2_Atom with a type specified by atom:bufferType.</p>
 
 <p>This is an abstract port type with incomplete semantics which can not be
 used directly as a port type.  Atom ports should be either a atom:ValuePort or
 a atom:MessagePort.</p>
 
-<p>Before calling a method on a plugin that writes to an AtomPort output, the
-host MUST set the size of the Atom in that output to the amount of available
-memory immediately following the Atom header.  The plugin MUST write a valid
-Atom to that port; leaving it untouched is illegal.  If there is no reasonable
-value to write to the port, the plugin MUST write null (the Atom with both
-<code>type</code> and <code>size</code> 0).</p>
+<p>Output ports with a variably sized type should be initialised by the host
+before every run to an atom:Chunk with size set to the available space.  The
+plugin must set the size and type of this atom appropriately when writing
+output.</p>
 """ .
 
 atom:ValuePort
@@ -473,7 +476,7 @@ number of times).</p>
 atom:bufferType
 	a rdf:Property ;
 	rdfs:domain atom:AtomPort ;
-	rdfs:label "buffer type" ;
+	rdfs:label "Buffer type" ;
 	lv2:documentation """
 <p>Indicates that an AtomPort may be connected to a certain Atom type.  A port
 MAY support several buffer types.  The host MUST NOT connect a port to an Atom
@@ -489,18 +492,14 @@ connected directly to an LV2_Atom_Double value is described like so:</p>
     ] .
 </pre>
 
-<p>Note this property only indicates the atom types a port may be directly
-connected to, it is not <q>recursive</q>.  If a port can be connected to a
-collection, use atom:supports to indicate which element types are understood.
-If a port supports heterogeneous collections (collections that can contain
-several types of elements at once), implementations MUST gracefully handle any
-types that are present in the collection, even if those types are not
-explicitly supported.</p>
+<p>This property only describes the types a port may be <em>directly</em>
+connected to.  It says nothing about the expected contents of containers.  For
+that, use atom:supports.</p>
 """ .
 
 atom:supports
 	a rdf:Property ;
-	rdfs:label "supports" ;
+	rdfs:label "Supports" ;
 	lv2:documentation """
 <p>Indicates that a particular Atom type is supported.</p>
 
@@ -509,8 +508,8 @@ atom:supports
 <q>recursively</q> where collections are involved.</p>
 
 <p>In particular, this property can be used to describe which event types are
-supported by a port.  For example, a port that receives MIDI events is
-described like so:</p>
+supported or <q>understood</q> by a port.  For example, a port that receives
+MIDI events is described like so:</p>
 
 <pre class="turtle-code">
 &lt;plugin&gt;
diff --git a/plugins/eg-sampler.lv2/sampler.c b/plugins/eg-sampler.lv2/sampler.c
index b7851cc..e141aeb 100644
--- a/plugins/eg-sampler.lv2/sampler.c
+++ b/plugins/eg-sampler.lv2/sampler.c
@@ -87,9 +87,9 @@ typedef struct {
 	Sample* sample;
 
 	/* Ports */
-	float*                output_port;
-	LV2_Atom_Port_Buffer* control_port;
-	LV2_Atom_Port_Buffer* notify_port;
+	float*             output_port;
+	LV2_Atom_Sequence* control_port;
+	LV2_Atom_Sequence* notify_port;
 
 	/* URIs */
 	SamplerURIs uris;
@@ -218,10 +218,10 @@ connect_port(LV2_Handle instance,
 
 	switch (port) {
 	case SAMPLER_CONTROL:
-		plugin->control_port = (LV2_Atom_Port_Buffer*)data;
+		plugin->control_port = (LV2_Atom_Sequence*)data;
 		break;
 	case SAMPLER_RESPONSE:
-		plugin->notify_port = (LV2_Atom_Port_Buffer*)data;
+		plugin->notify_port = (LV2_Atom_Sequence*)data;
 		break;
 	case SAMPLER_OUT:
 		plugin->output_port = (float*)data;
@@ -329,7 +329,7 @@ run(LV2_Handle instance,
 	float*       output      = plugin->output_port;
 
 	/* Read incoming events */
-	LV2_SEQUENCE_FOREACH((LV2_Atom_Sequence*)plugin->control_port->data, i) {
+	LV2_SEQUENCE_FOREACH(plugin->control_port, i) {
 		LV2_Atom_Event* const ev = lv2_sequence_iter_get(i);
 		if (ev->body.type == uris->midi_Event) {
 			uint8_t* const data = (uint8_t* const)(ev + 1);
@@ -382,13 +382,18 @@ run(LV2_Handle instance,
 	}
 
 	/* Set up forge to write directly to notify output port buffer */
-	LV2_Atom* seq = plugin->notify_port->data;
+	const uint32_t notify_capacity = plugin->notify_port->atom.size;
+
+	LV2_Atom_Sequence* seq = (LV2_Atom_Sequence*)plugin->notify_port;
+	seq->atom.type = uris->atom_Sequence;
+	seq->atom.size = seq->body.unit = seq->body.pad = 0;
+
+	lv2_atom_forge_set_buffer(&plugin->forge,
+	                          LV2_ATOM_CONTENTS(LV2_Atom_Sequence, seq),
+	                          notify_capacity);
+
 	LV2_Atom_Forge_Frame seq_frame;
-	lv2_atom_forge_push(&plugin->forge, &seq_frame, seq);
-	lv2_atom_forge_set_buffer(
-		&plugin->forge,
-		LV2_ATOM_CONTENTS(LV2_Atom_Sequence, seq),
-		plugin->notify_port->capacity);
+	lv2_atom_forge_push(&plugin->forge, &seq_frame, &seq->atom);
 
 	/* Read messages from worker thread */
 	SampleMessage  m;
diff --git a/plugins/eg-sampler.lv2/uris.h b/plugins/eg-sampler.lv2/uris.h
index 8d0a983..cec1700 100644
--- a/plugins/eg-sampler.lv2/uris.h
+++ b/plugins/eg-sampler.lv2/uris.h
@@ -31,6 +31,7 @@ typedef struct {
 	LV2_URID atom_Blank;
 	LV2_URID atom_Path;
 	LV2_URID atom_Resource;
+	LV2_URID atom_Sequence;
 	LV2_URID atom_eventTransfer;
 	LV2_URID eg_applySample;
 	LV2_URID eg_file;
@@ -46,6 +47,7 @@ map_sampler_uris(LV2_URID_Map* map, SamplerURIs* uris)
 	uris->atom_Blank         = map->map(map->handle, LV2_ATOM__Blank);
 	uris->atom_Path          = map->map(map->handle, LV2_ATOM__Path);
 	uris->atom_Resource      = map->map(map->handle, LV2_ATOM__Resource);
+	uris->atom_Sequence      = map->map(map->handle, LV2_ATOM__Sequence);
 	uris->atom_eventTransfer = map->map(map->handle, LV2_ATOM__eventTransfer);
 	uris->eg_applySample     = map->map(map->handle, EG_SAMPLER__applySample);
 	uris->eg_file            = map->map(map->handle, EG_SAMPLER__file);