An API for constructing LV2 atoms. More...

Data Structures
struct	LV2_Atom_Forge_Frame
	A stack frame used for keeping track of nested Atom containers. More...
struct	LV2_Atom_Forge
	A "forge" for creating atoms by appending to a buffer. More...
Defines
#define	LV2_ATOM_FORGE_DEPRECATED
Typedefs
typedef void *	LV2_Atom_Forge_Sink_Handle
	Handle for LV2_Atom_Forge_Sink.
typedef intptr_t	LV2_Atom_Forge_Ref
	A reference to a chunk of written output.
typedef LV2_Atom_Forge_Ref(*	LV2_Atom_Forge_Sink )(LV2_Atom_Forge_Sink_Handle handle, const void *buf, uint32_t size)
	Sink function for writing output.
typedef LV2_Atom (	LV2_Atom_Forge_Deref_Func )(LV2_Atom_Forge_Sink_Handle handle, LV2_Atom_Forge_Ref ref)
	Function for resolving a reference.
Functions
static void	lv2_atom_forge_init (LV2_Atom_Forge forge, LV2_URID_Map map)
	Initialise `forge`.
static LV2_Atom *	lv2_atom_forge_deref (LV2_Atom_Forge *forge, LV2_Atom_Forge_Ref ref)
Output Configuration
static void	lv2_atom_forge_set_buffer (LV2_Atom_Forge forge, uint8_t buf, size_t size)
	Set the output buffer where `forge` will write atoms.
static void	lv2_atom_forge_set_sink (LV2_Atom_Forge *forge, LV2_Atom_Forge_Sink sink, LV2_Atom_Forge_Deref_Func deref, LV2_Atom_Forge_Sink_Handle handle)
	Set the sink function where `forge` will write output.
Object Stack
static LV2_Atom_Forge_Ref	lv2_atom_forge_push (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame, LV2_Atom_Forge_Ref ref)
	Push a stack frame.
static void	lv2_atom_forge_pop (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame)
	Pop a stack frame.
static bool	lv2_atom_forge_top_is (LV2_Atom_Forge *forge, uint32_t type)
	Return true iff the top of the stack has the given type.
static bool	lv2_atom_forge_is_object_type (const LV2_Atom_Forge *forge, uint32_t type)
	Return true iff `type` is an atom:Object.
static bool	lv2_atom_forge_is_blank (const LV2_Atom_Forge forge, uint32_t type, const LV2_Atom_Object_Body body)
	Return true iff `type` is an atom:Object with a blank ID.
Low Level Output
static LV2_Atom_Forge_Ref	lv2_atom_forge_raw (LV2_Atom_Forge forge, const void data, uint32_t size)
	Write raw output.
static void	lv2_atom_forge_pad (LV2_Atom_Forge *forge, uint32_t written)
	Pad output accordingly so next write is 64-bit aligned.
static LV2_Atom_Forge_Ref	lv2_atom_forge_write (LV2_Atom_Forge forge, const void data, uint32_t size)
	Write raw output, padding to 64-bits as necessary.
static LV2_Atom_Forge_Ref	lv2_atom_forge_string_body (LV2_Atom_Forge forge, const char str, uint32_t len)
	Write a null-terminated string body.
Atom Output
static LV2_Atom_Forge_Ref	lv2_atom_forge_atom (LV2_Atom_Forge *forge, uint32_t size, uint32_t type)
	Write an atom:Atom header.
static LV2_Atom_Forge_Ref	lv2_atom_forge_primitive (LV2_Atom_Forge forge, const LV2_Atom a)
	Write a primitive (fixed-size) atom.
static LV2_Atom_Forge_Ref	lv2_atom_forge_int (LV2_Atom_Forge *forge, int32_t val)
	Write an atom:Int.
static LV2_Atom_Forge_Ref	lv2_atom_forge_long (LV2_Atom_Forge *forge, int64_t val)
	Write an atom:Long.
static LV2_Atom_Forge_Ref	lv2_atom_forge_float (LV2_Atom_Forge *forge, float val)
	Write an atom:Float.
static LV2_Atom_Forge_Ref	lv2_atom_forge_double (LV2_Atom_Forge *forge, double val)
	Write an atom:Double.
static LV2_Atom_Forge_Ref	lv2_atom_forge_bool (LV2_Atom_Forge *forge, bool val)
	Write an atom:Bool.
static LV2_Atom_Forge_Ref	lv2_atom_forge_urid (LV2_Atom_Forge *forge, LV2_URID id)
	Write an atom:URID.
static LV2_Atom_Forge_Ref	lv2_atom_forge_typed_string (LV2_Atom_Forge forge, uint32_t type, const char str, uint32_t len)
	Write an atom compatible with atom:String.
static LV2_Atom_Forge_Ref	lv2_atom_forge_string (LV2_Atom_Forge forge, const char str, uint32_t len)
	Write an atom:String.
static LV2_Atom_Forge_Ref	lv2_atom_forge_uri (LV2_Atom_Forge forge, const char uri, uint32_t len)
	Write an atom:URI.
static LV2_Atom_Forge_Ref	lv2_atom_forge_path (LV2_Atom_Forge forge, const char path, uint32_t len)
	Write an atom:Path.
static LV2_Atom_Forge_Ref	lv2_atom_forge_literal (LV2_Atom_Forge forge, const char str, uint32_t len, uint32_t datatype, uint32_t lang)
	Write an atom:Literal.
static LV2_Atom_Forge_Ref	lv2_atom_forge_vector_head (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame, uint32_t child_size, uint32_t child_type)
	Start an atom:Vector.
static LV2_Atom_Forge_Ref	lv2_atom_forge_vector (LV2_Atom_Forge forge, uint32_t child_size, uint32_t child_type, uint32_t n_elems, const void elems)
	Write a complete atom:Vector.
static LV2_Atom_Forge_Ref	lv2_atom_forge_tuple (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame)
	Write the header of an atom:Tuple.
static LV2_Atom_Forge_Ref	lv2_atom_forge_object (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame, LV2_URID id, LV2_URID otype)
	Write the header of an atom:Object.
static LV2_ATOM_FORGE_DEPRECATED LV2_Atom_Forge_Ref	lv2_atom_forge_resource (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame, LV2_URID id, LV2_URID otype)
	The same as lv2_atom_forge_object(), but for object:Resource.
static LV2_ATOM_FORGE_DEPRECATED LV2_Atom_Forge_Ref	lv2_atom_forge_blank (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame, uint32_t id, LV2_URID otype)
	The same as lv2_atom_forge_object(), but for object:Blank.
static LV2_Atom_Forge_Ref	lv2_atom_forge_key (LV2_Atom_Forge *forge, LV2_URID key)
	Write a property key in an Object, to be followed by the value.
static LV2_Atom_Forge_Ref	lv2_atom_forge_property_head (LV2_Atom_Forge *forge, LV2_URID key, LV2_URID context)
	Write the header for a property body in an object, with context.
static LV2_Atom_Forge_Ref	lv2_atom_forge_sequence_head (LV2_Atom_Forge forge, LV2_Atom_Forge_Frame frame, uint32_t unit)
	Write the header for a Sequence.
static LV2_Atom_Forge_Ref	lv2_atom_forge_frame_time (LV2_Atom_Forge *forge, int64_t frames)
	Write the time stamp header of an Event (in a Sequence) in audio frames.
static LV2_Atom_Forge_Ref	lv2_atom_forge_beat_time (LV2_Atom_Forge *forge, double beats)
	Write the time stamp header of an Event (in a Sequence) in beats.

Detailed Description

An API for constructing LV2 atoms.

This file provides an API for constructing Atoms which makes it relatively simple to build nested atoms of arbitrary complexity without requiring dynamic memory allocation.

The API is based on successively appending the appropriate pieces to build a complete Atom. The size of containers is automatically updated. Functions that begin a container return (via their frame argument) a stack frame which must be popped when the container is finished.

All output is written to a user-provided buffer or sink function. This makes it popssible to create create atoms on the stack, on the heap, in LV2 port buffers, in a ringbuffer, or elsewhere, all using the same API.

This entire API is realtime safe if used with a buffer or a realtime safe sink, except lv2_atom_forge_init() which is only realtime safe if the URI map function is.

Note these functions are all static inline, do not take their address.

This header is non-normative, it is provided for convenience.

Define Documentation

#define LV2_ATOM_FORGE_DEPRECATED

Typedef Documentation

typedef void* LV2_Atom_Forge_Sink_Handle

Handle for LV2_Atom_Forge_Sink.

typedef intptr_t LV2_Atom_Forge_Ref

A reference to a chunk of written output.

typedef LV2_Atom_Forge_Ref(* LV2_Atom_Forge_Sink)(LV2_Atom_Forge_Sink_Handle handle, const void *buf, uint32_t size)

Sink function for writing output.

See lv2_atom_forge_set_sink().

typedef LV2_Atom*(* LV2_Atom_Forge_Deref_Func)(LV2_Atom_Forge_Sink_Handle handle, LV2_Atom_Forge_Ref ref)

Function for resolving a reference.

See lv2_atom_forge_set_sink().

Function Documentation

static void lv2_atom_forge_set_buffer	(	LV2_Atom_Forge *	forge,
		uint8_t *	buf,
		size_t	size
	)		`[inline, static]`

Set the output buffer where `forge` will write atoms.

static void lv2_atom_forge_init	(	LV2_Atom_Forge *	forge,
		LV2_URID_Map *	map
	)		`[inline, static]`

Initialise `forge`.

URIs will be mapped using `map` and stored, a reference to `map` itself is not held.

static LV2_Atom* lv2_atom_forge_deref	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Ref	ref
	)		`[inline, static]`

static LV2_Atom_Forge_Ref lv2_atom_forge_push	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame,
		LV2_Atom_Forge_Ref	ref
	)		`[inline, static]`

Push a stack frame.

This is done automatically by container functions (which take a stack frame pointer), but may be called by the user to push the top level container when writing to an existing Atom.

static void lv2_atom_forge_pop	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame
	)		`[inline, static]`

Pop a stack frame.

This must be called when a container is finished.

static bool lv2_atom_forge_top_is	(	LV2_Atom_Forge *	forge,
		uint32_t	type
	)		`[inline, static]`

Return true iff the top of the stack has the given type.

static bool lv2_atom_forge_is_object_type	(	const LV2_Atom_Forge *	forge,
		uint32_t	type
	)		`[inline, static]`

Return true iff `type` is an atom:Object.

static bool lv2_atom_forge_is_blank	(	const LV2_Atom_Forge *	forge,
		uint32_t	type,
		const LV2_Atom_Object_Body *	body
	)		`[inline, static]`

Return true iff `type` is an atom:Object with a blank ID.

static void lv2_atom_forge_set_sink	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Sink	sink,
		LV2_Atom_Forge_Deref_Func	deref,
		LV2_Atom_Forge_Sink_Handle	handle
	)		`[inline, static]`

Set the sink function where `forge` will write output.

The return value of forge functions is an LV2_Atom_Forge_Ref which is an integer type safe to use as a pointer but is otherwise opaque. The sink function must return a ref that can be dereferenced to access as least sizeof(LV2_Atom) bytes of the written data, so sizes can be updated. For ringbuffers, this should be possible as long as the size of the buffer is a multiple of sizeof(LV2_Atom), since atoms are always aligned.

Note that 0 is an invalid reference, so if you are using a buffer offset be sure to offset it such that 0 is never a valid reference. You will get confusing errors otherwise.

static LV2_Atom_Forge_Ref lv2_atom_forge_raw	(	LV2_Atom_Forge *	forge,
		const void *	data,
		uint32_t	size
	)		`[inline, static]`

Write raw output.

This is used internally, but is also useful for writing atom types not explicitly supported by the forge API. Note the caller is responsible for ensuring the output is approriately padded.

static void lv2_atom_forge_pad	(	LV2_Atom_Forge *	forge,
		uint32_t	written
	)		`[inline, static]`

Pad output accordingly so next write is 64-bit aligned.

static LV2_Atom_Forge_Ref lv2_atom_forge_write	(	LV2_Atom_Forge *	forge,
		const void *	data,
		uint32_t	size
	)		`[inline, static]`

Write raw output, padding to 64-bits as necessary.

static LV2_Atom_Forge_Ref lv2_atom_forge_string_body	(	LV2_Atom_Forge *	forge,
		const char *	str,
		uint32_t	len
	)		`[inline, static]`

Write a null-terminated string body.

static LV2_Atom_Forge_Ref lv2_atom_forge_atom	(	LV2_Atom_Forge *	forge,
		uint32_t	size,
		uint32_t	type
	)		`[inline, static]`

Write an atom:Atom header.

static LV2_Atom_Forge_Ref lv2_atom_forge_primitive	(	LV2_Atom_Forge *	forge,
		const LV2_Atom *	a
	)		`[inline, static]`

Write a primitive (fixed-size) atom.

static LV2_Atom_Forge_Ref lv2_atom_forge_int	(	LV2_Atom_Forge *	forge,
		int32_t	val
	)		`[inline, static]`

Write an atom:Int.

static LV2_Atom_Forge_Ref lv2_atom_forge_long	(	LV2_Atom_Forge *	forge,
		int64_t	val
	)		`[inline, static]`

Write an atom:Long.

static LV2_Atom_Forge_Ref lv2_atom_forge_float	(	LV2_Atom_Forge *	forge,
		float	val
	)		`[inline, static]`

Write an atom:Float.

static LV2_Atom_Forge_Ref lv2_atom_forge_double	(	LV2_Atom_Forge *	forge,
		double	val
	)		`[inline, static]`

Write an atom:Double.

static LV2_Atom_Forge_Ref lv2_atom_forge_bool	(	LV2_Atom_Forge *	forge,
		bool	val
	)		`[inline, static]`

Write an atom:Bool.

static LV2_Atom_Forge_Ref lv2_atom_forge_urid	(	LV2_Atom_Forge *	forge,
		LV2_URID	id
	)		`[inline, static]`

Write an atom:URID.

static LV2_Atom_Forge_Ref lv2_atom_forge_typed_string	(	LV2_Atom_Forge *	forge,
		uint32_t	type,
		const char *	str,
		uint32_t	len
	)		`[inline, static]`

Write an atom compatible with atom:String.

Used internally.

static LV2_Atom_Forge_Ref lv2_atom_forge_string	(	LV2_Atom_Forge *	forge,
		const char *	str,
		uint32_t	len
	)		`[inline, static]`

Write an atom:String.

Note that `str` need not be NULL terminated.

static LV2_Atom_Forge_Ref lv2_atom_forge_uri	(	LV2_Atom_Forge *	forge,
		const char *	uri,
		uint32_t	len
	)		`[inline, static]`

Write an atom:URI.

Note that `uri` need not be NULL terminated. This does not map the URI, but writes the complete URI string. To write a mapped URI, use lv2_atom_forge_urid().

static LV2_Atom_Forge_Ref lv2_atom_forge_path	(	LV2_Atom_Forge *	forge,
		const char *	path,
		uint32_t	len
	)		`[inline, static]`

Write an atom:Path.

Note that `path` need not be NULL terminated.

static LV2_Atom_Forge_Ref lv2_atom_forge_literal	(	LV2_Atom_Forge *	forge,
		const char *	str,
		uint32_t	len,
		uint32_t	datatype,
		uint32_t	lang
	)		`[inline, static]`

Write an atom:Literal.

static LV2_Atom_Forge_Ref lv2_atom_forge_vector_head	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame,
		uint32_t	child_size,
		uint32_t	child_type
	)		`[inline, static]`

Start an atom:Vector.

static LV2_Atom_Forge_Ref lv2_atom_forge_vector	(	LV2_Atom_Forge *	forge,
		uint32_t	child_size,
		uint32_t	child_type,
		uint32_t	n_elems,
		const void *	elems
	)		`[inline, static]`

Write a complete atom:Vector.

static LV2_Atom_Forge_Ref lv2_atom_forge_tuple	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame
	)		`[inline, static]`

Write the header of an atom:Tuple.

The passed frame will be initialised to represent this tuple. To complete the tuple, write a sequence of atoms, then pop the frame with lv2_atom_forge_pop().

For example:

   // Write tuple (1, 2.0)
   LV2_Atom_Forge_Frame frame;
   LV2_Atom* tup = (LV2_Atom*)lv2_atom_forge_tuple(forge, &frame);
   lv2_atom_forge_int32(forge, 1);
   lv2_atom_forge_float(forge, 2.0);
   lv2_atom_forge_pop(forge, &frame);

static LV2_Atom_Forge_Ref lv2_atom_forge_object	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame,
		LV2_URID	id,
		LV2_URID	otype
	)		`[inline, static]`

Write the header of an atom:Object.

The passed frame will be initialised to represent this object. To complete the object, write a sequence of properties, then pop the frame with lv2_atom_forge_pop().

For example:

   LV2_URID eg_Cat  = map("http://example.org/Cat");
   LV2_URID eg_name = map("http://example.org/name");

   // Start object with type eg_Cat and blank ID
   LV2_Atom_Forge_Frame frame;
   lv2_atom_forge_object(forge, &frame, 0, eg_Cat);

   // Append property eg:name = "Hobbes"
   lv2_atom_forge_key(forge, eg_name);
   lv2_atom_forge_string(forge, "Hobbes", strlen("Hobbes"));

   // Finish object
   lv2_atom_forge_pop(forge, &frame);

static LV2_ATOM_FORGE_DEPRECATED LV2_Atom_Forge_Ref lv2_atom_forge_resource	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame,
		LV2_URID	id,
		LV2_URID	otype
	)		`[inline, static]`

The same as lv2_atom_forge_object(), but for object:Resource.

This function is deprecated and should not be used in new code. Use lv2_atom_forge_object() directly instead.

static LV2_ATOM_FORGE_DEPRECATED LV2_Atom_Forge_Ref lv2_atom_forge_blank	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame,
		uint32_t	id,
		LV2_URID	otype
	)		`[inline, static]`

The same as lv2_atom_forge_object(), but for object:Blank.

This function is deprecated and should not be used in new code. Use lv2_atom_forge_object() directly instead.

static LV2_Atom_Forge_Ref lv2_atom_forge_key	(	LV2_Atom_Forge *	forge,
		LV2_URID	key
	)		`[inline, static]`

Write a property key in an Object, to be followed by the value.

See lv2_atom_forge_object() documentation for an example.

static LV2_Atom_Forge_Ref lv2_atom_forge_property_head	(	LV2_Atom_Forge *	forge,
		LV2_URID	key,
		LV2_URID	context
	)		`[inline, static]`

Write the header for a property body in an object, with context.

If you do not need the context, which is almost certainly the case, use the simpler lv2_atom_forge_key() instead.

static LV2_Atom_Forge_Ref lv2_atom_forge_sequence_head	(	LV2_Atom_Forge *	forge,
		LV2_Atom_Forge_Frame *	frame,
		uint32_t	unit
	)		`[inline, static]`

Write the header for a Sequence.

static LV2_Atom_Forge_Ref lv2_atom_forge_frame_time	(	LV2_Atom_Forge *	forge,
		int64_t	frames
	)		`[inline, static]`

Write the time stamp header of an Event (in a Sequence) in audio frames.

After this, call the appropriate forge method(s) to write the body. Note the returned reference is to an LV2_Event which is NOT an Atom.

static LV2_Atom_Forge_Ref lv2_atom_forge_beat_time	(	LV2_Atom_Forge *	forge,
		double	beats
	)		`[inline, static]`

Write the time stamp header of an Event (in a Sequence) in beats.

After this, call the appropriate forge method(s) to write the body. Note the returned reference is to an LV2_Event which is NOT an Atom.

Data Structures

Defines

Typedefs

Functions

Detailed Description

Define Documentation

Typedef Documentation

Function Documentation