aboutsummaryrefslogtreecommitdiffstats
path: root/lv2/lv2plug.in/ns/ext/atom/forge.h
blob: d13f549e462ec61a25d7f12e4600b74c08bf75c6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
/*
  Copyright 2008-2012 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 forge.h An API for constructing LV2 atoms.

   This file provides a simple API which can be used to create complex nested
   atoms by calling the provided functions to append atoms (or atom headers) in
   the correct order.

   The size of containers is automatically handled to any depth.  All functions
   that start a container take a pointer to an uninitialised stack frame which
   will be initialised and must be popped when the container is finished.

   All output is written to a user-provided buffer, or sink function.  Thus,
   this API can be used to create atoms on the stack, on the heap, in LV2 port
   buffers, or in a ringbuffer.

   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.
*/

#ifndef LV2_ATOM_FORGE_H
#define LV2_ATOM_FORGE_H

#include <assert.h>

#include "lv2/lv2plug.in/ns/ext/atom/atom-helpers.h"
#include "lv2/lv2plug.in/ns/ext/atom/atom.h"
#include "lv2/lv2plug.in/ns/ext/urid/urid.h"

#ifdef __cplusplus
extern "C" {
#else
#    include <stdbool.h>
#endif

/** Handle for LV2_Atom_Forge_Sink. */
typedef void* LV2_Atom_Forge_Sink_Handle;

/** Sink function for writing output.  See lv2_atom_forge_set_sink(). */
typedef void* (*LV2_Atom_Forge_Sink)(LV2_Atom_Forge_Sink_Handle handle,
                                     const void*                buf,
                                     uint32_t                   size);

/** A stack frame used for keeping track of nested Atom containers. */
typedef struct _LV2_Atom_Forge_Frame {
	struct _LV2_Atom_Forge_Frame* parent;
	LV2_Atom*                     atom;
} LV2_Atom_Forge_Frame;

/** A "forge" for creating atoms by appending to a buffer. */
typedef struct {
	uint8_t* buf;
	uint32_t offset;
	uint32_t size;

	LV2_Atom_Forge_Sink        sink;
	LV2_Atom_Forge_Sink_Handle handle;

	LV2_Atom_Forge_Frame* stack;

	LV2_URID Blank;
	LV2_URID Bool;
	LV2_URID Double;
	LV2_URID Float;
	LV2_URID Int32;
	LV2_URID Int64;
	LV2_URID Literal;
	LV2_URID Path;
	LV2_URID Property;
	LV2_URID Resource;
	LV2_URID Sequence;
	LV2_URID String;
	LV2_URID Tuple;
	LV2_URID URI;
	LV2_URID URID;
	LV2_URID Vector;
} LV2_Atom_Forge;

/**
   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 inline LV2_Atom*
lv2_atom_forge_push(LV2_Atom_Forge*       forge,
                    LV2_Atom_Forge_Frame* frame,
                    LV2_Atom*             atom)
{
	frame->parent = forge->stack;
	frame->atom   = atom;
	forge->stack  = frame;
	return atom;
}

/** Pop a stack frame.  This must be called when a container is finished. */
static inline void
lv2_atom_forge_pop(LV2_Atom_Forge* forge, LV2_Atom_Forge_Frame* frame)
{
	assert(frame == forge->stack);
	forge->stack = frame->parent;
}

/** Set the output buffer where @p forge will write atoms. */
static inline void
lv2_atom_forge_set_buffer(LV2_Atom_Forge* forge, uint8_t* buf, size_t size)
{
	forge->buf    = buf;
	forge->size   = size;
	forge->offset = 0;
	forge->sink   = NULL;
	forge->handle = NULL;
}

/**
   Set the sink function where @p forge will write output.

   The return value of forge functions is a pointer to the written data, which
   is used for updating parent sizes.  To enable this, the sink function must
   return a valid pointer to a contiguous LV2_Atom header.  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.  When using a ringbuffer,
   the returned pointers may not point to a complete atom (including body).
   The user must take care to only use these return values in a way compatible
   with the sink used.
*/
static inline void
lv2_atom_forge_set_sink(LV2_Atom_Forge*            forge,
                        LV2_Atom_Forge_Sink        sink,
                        LV2_Atom_Forge_Sink_Handle handle)
{
	forge->buf    = NULL;
	forge->size   = forge->offset = 0;
	forge->sink   = sink;
	forge->handle = handle;
}

/**
   Initialise @p forge.

   URIs will be mapped using @p map and stored, a reference to @p map itself is
   not held.
*/
static inline void
lv2_atom_forge_init(LV2_Atom_Forge* forge, LV2_URID_Map* map)
{
	lv2_atom_forge_set_buffer(forge, NULL, 0);
	forge->stack    = NULL;
	forge->Blank    = map->map(map->handle, LV2_ATOM_URI "#Blank");
	forge->Bool     = map->map(map->handle, LV2_ATOM_URI "#Bool");
	forge->Double   = map->map(map->handle, LV2_ATOM_URI "#Double");
	forge->Float    = map->map(map->handle, LV2_ATOM_URI "#Float");
	forge->Int32    = map->map(map->handle, LV2_ATOM_URI "#Int32");
	forge->Int64    = map->map(map->handle, LV2_ATOM_URI "#Int64");
	forge->Literal  = map->map(map->handle, LV2_ATOM_URI "#Literal");
	forge->Path     = map->map(map->handle, LV2_ATOM_URI "#Path");
	forge->Property = map->map(map->handle, LV2_ATOM_URI "#Property");
	forge->Resource = map->map(map->handle, LV2_ATOM_URI "#Resource");
	forge->Sequence = map->map(map->handle, LV2_ATOM_URI "#Sequence");
	forge->String   = map->map(map->handle, LV2_ATOM_URI "#String");
	forge->Tuple    = map->map(map->handle, LV2_ATOM_URI "#Tuple");
	forge->URI      = map->map(map->handle, LV2_ATOM_URI "#URI");
	forge->URID     = map->map(map->handle, LV2_ATOM_URI "#URID");
	forge->Vector   = map->map(map->handle, LV2_ATOM_URI "#Vector");
}

static inline void*
lv2_atom_forge_write_nopad(LV2_Atom_Forge* forge,
                           const void*     data,
                           uint32_t        size)
{
	uint8_t* out = NULL;
	if (forge->sink) {
		out = forge->sink(forge->handle, data, size);
	} else {
		out = forge->buf + forge->offset;
		if (forge->offset + size > forge->size) {
			return NULL;
		}
		forge->offset += size;
		memcpy(out, data, size);
	}
	if (out) {
		for (LV2_Atom_Forge_Frame* f = forge->stack; f; f = f->parent) {
			f->atom->size += size;
		}
	}
	return out;
}

static inline void
lv2_atom_forge_pad(LV2_Atom_Forge* forge,
                   uint32_t        written)
{
	const uint64_t pad      = 0;
	const uint32_t pad_size = lv2_atom_pad_size(written) - written;
	lv2_atom_forge_write_nopad(forge, &pad, pad_size);
}

static inline void*
lv2_atom_forge_write(LV2_Atom_Forge* forge,
                     const void*     data,
                     uint32_t        size)
{
	void* out = lv2_atom_forge_write_nopad(forge, data, size);
	if (out) {
		lv2_atom_forge_pad(forge, size);
	}
	return out;
}

/** Write an atom:Int32. */
static inline LV2_Atom_Int32*
lv2_atom_forge_int32(LV2_Atom_Forge* forge, int32_t val)
{
	const LV2_Atom_Int32 a = { { forge->Int32, sizeof(val) }, val };
	return (LV2_Atom_Int32*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/** Write an atom:Int64. */
static inline LV2_Atom_Int64*
lv2_atom_forge_int64(LV2_Atom_Forge* forge, int64_t val)
{
	const LV2_Atom_Int64 a = { { forge->Int64, sizeof(val) }, val };
	return (LV2_Atom_Int64*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/** Write an atom:Float. */
static inline LV2_Atom_Float*
lv2_atom_forge_float(LV2_Atom_Forge* forge, float val)
{
	const LV2_Atom_Float a = { { forge->Float, sizeof(val) }, val };
	return (LV2_Atom_Float*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/** Write an atom:Double. */
static inline LV2_Atom_Double*
lv2_atom_forge_double(LV2_Atom_Forge* forge, double val)
{
	const LV2_Atom_Double a = { { forge->Double, sizeof(val) }, val };
	return (LV2_Atom_Double*)lv2_atom_forge_write(
		forge, &a, sizeof(a));
}

/** Write an atom:Bool. */
static inline LV2_Atom_Bool*
lv2_atom_forge_bool(LV2_Atom_Forge* forge, bool val)
{
	const LV2_Atom_Bool a = { { forge->Bool, sizeof(val) }, val };
	return (LV2_Atom_Bool*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/** Write an atom:URID. */
static inline LV2_Atom_URID*
lv2_atom_forge_urid(LV2_Atom_Forge* forge, LV2_URID id)
{
	const LV2_Atom_URID a = { { forge->Int32, sizeof(id) }, id };
	return (LV2_Atom_URID*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/** Write a string body.  Used internally. */
static inline uint8_t*
lv2_atom_forge_string_body(LV2_Atom_Forge* forge,
                           const uint8_t*  str,
                           size_t          len)
{
	uint8_t* out = NULL;
	if ((out = lv2_atom_forge_write_nopad(forge, str, len))
	    && (out = lv2_atom_forge_write_nopad(forge, "", 1))) {
		lv2_atom_forge_pad(forge, len + 1);
	}
	return out;
}

/** Write an atom:String.  Note that @p str need not be NULL terminated. */
static inline LV2_Atom_String*
lv2_atom_forge_string(LV2_Atom_Forge* forge,
                      const uint8_t*  str,
                      size_t          len)
{
	const LV2_Atom_String a = { { forge->String, len + 1 } };
	LV2_Atom_String* out = (LV2_Atom_String*)
		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
	if (out) {
		if (!lv2_atom_forge_string_body(forge, str, len)) {
			out->atom.type = 0;
			out->atom.size = 0;
			out = NULL;
		}
	}
	return out;
}

/**
   Write an atom:URI.  Note that @p 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 inline LV2_Atom_String*
lv2_atom_forge_uri(LV2_Atom_Forge* forge,
                   const uint8_t*  uri,
                   size_t          len)
{
	const LV2_Atom_String a = { { forge->URI, len + 1 } };
	LV2_Atom_String* out = (LV2_Atom_String*)
		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
	if (out) {
		if (!lv2_atom_forge_string_body(forge, uri, len)) {
			out->atom.type = 0;
			out->atom.size = 0;
			out = NULL;
		}
	}
	return out;
}

/** Write an atom:Path.  Note that @p path need not be NULL terminated. */
static inline LV2_Atom_String*
lv2_atom_forge_path(LV2_Atom_Forge* forge,
                    const uint8_t*  path,
                    size_t          len)
{
	const LV2_Atom_String a = { { forge->Path, len + 1 } };
	LV2_Atom_String* out = (LV2_Atom_String*)
		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
	if (out) {
		if (!lv2_atom_forge_string_body(forge, path, len)) {
			out->atom.type = 0;
			out->atom.size = 0;
			out = NULL;
		}
	}
	return out;
}

/** Write an atom:Literal. */
static inline LV2_Atom_Literal*
lv2_atom_forge_literal(LV2_Atom_Forge* forge,
                       const uint8_t*  str,
                       size_t          len,
                       uint32_t        datatype,
                       uint32_t        lang)
{
	const LV2_Atom_Literal a = {
		{ forge->Literal,
		  sizeof(LV2_Atom_Literal) - sizeof(LV2_Atom) + len + 1 },
		datatype,
		lang
	};
	LV2_Atom_Literal* out = (LV2_Atom_Literal*)
		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
	if (out) {
		if (!lv2_atom_forge_string_body(forge, str, len)) {
			out->atom.type = 0;
			out->atom.size = 0;
			out = NULL;
		}
	}
	return out;
}

/** Write an atom:Vector header, but not the vector body. */
static inline LV2_Atom_Vector*
lv2_atom_forge_vector_head(LV2_Atom_Forge* forge,
                           uint32_t        elem_count,
                           uint32_t        elem_type,
                           uint32_t        elem_size)
{
	const size_t size = sizeof(LV2_Atom_Vector) + (elem_size * elem_count);
	const LV2_Atom_Vector a = {
		{ forge->Vector, size - sizeof(LV2_Atom) },
		elem_count,
		elem_type
	};
	return (LV2_Atom_Vector*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/** Write a complete atom:Vector. */
static inline LV2_Atom_Vector*
lv2_atom_forge_vector(LV2_Atom_Forge* forge,
                      uint32_t        elem_count,
                      uint32_t        elem_type,
                      uint32_t        elem_size,
                      void*           elems)
{
	LV2_Atom_Vector* out = lv2_atom_forge_vector_head(
		forge, elem_count, elem_type, elem_size);
	if (out) {
		lv2_atom_forge_write(forge, elems, elem_size * elem_count);
	}
	return out;
}

/**
   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:
   @code
   // 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);
   @endcode
*/
static inline LV2_Atom_Tuple*
lv2_atom_forge_tuple(LV2_Atom_Forge* forge, LV2_Atom_Forge_Frame* frame)
{
	const LV2_Atom_Tuple a    = { { forge->Tuple, 0 } };
	LV2_Atom*            atom = lv2_atom_forge_write(forge, &a, sizeof(a));
	return (LV2_Atom_Tuple*)lv2_atom_forge_push(forge, frame, atom);
}

/**
   Write the header of an atom:Resource.

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

   // Write object header
   LV2_Atom_Forge_Frame frame;
   LV2_Atom* obj = (LV2_Atom*)lv2_atom_forge_resource(forge, &frame, 1, eg_Cat);

   // Write property: eg:name = "Hobbes"
   lv2_atom_forge_property_head(forge, eg_name, 0);
   lv2_atom_forge_string(forge, "Hobbes", strlen("Hobbes"));

   // Finish object
   lv2_atom_forge_pop(forge, &frame);
   @endcode
*/
static inline LV2_Atom_Object*
lv2_atom_forge_resource(LV2_Atom_Forge*       forge,
                        LV2_Atom_Forge_Frame* frame,
                        LV2_URID              id,
                        LV2_URID              otype)
{
	const LV2_Atom_Object a = {
		{ forge->Resource, sizeof(LV2_Atom_Object) - sizeof(LV2_Atom) },
		id,
		otype
	};
	LV2_Atom* atom = (LV2_Atom*)lv2_atom_forge_write(forge, &a, sizeof(a));
	return (LV2_Atom_Object*)lv2_atom_forge_push(forge, frame, atom);
}

/**
   The same as lv2_atom_forge_resource(), but for object:Blank.
*/
static inline LV2_Atom_Object*
lv2_atom_forge_blank(LV2_Atom_Forge*       forge,
                     LV2_Atom_Forge_Frame* frame,
                     uint32_t              id,
                     LV2_URID              otype)
{
	const LV2_Atom_Object a = {
		{ forge->Blank, sizeof(LV2_Atom_Object) - sizeof(LV2_Atom) },
		id,
		otype
	};
	LV2_Atom* atom = (LV2_Atom*)lv2_atom_forge_write(forge, &a, sizeof(a));
	return (LV2_Atom_Object*)lv2_atom_forge_push(forge, frame, atom);
}

/**
   Write the header for a property body (likely in an Object).
   See lv2_atom_forge_object() documentation for an example.
*/
static inline LV2_Atom_Property_Body*
lv2_atom_forge_property_head(LV2_Atom_Forge* forge,
                             LV2_URID        key,
                             LV2_URID        context)
{
	const LV2_Atom_Property_Body a = { key, context, { 0, 0 } };
	return (LV2_Atom_Property_Body*)lv2_atom_forge_write(
		forge, &a, 2 * sizeof(uint32_t));
}

/**
   Write the header for a Sequence.
   The size of the returned sequence will be 0, so passing it as the parent
   parameter to other forge methods will do the right thing.
*/
static inline LV2_Atom_Sequence*
lv2_atom_forge_sequence_head(LV2_Atom_Forge*       forge,
                             LV2_Atom_Forge_Frame* frame,
                             uint32_t              unit)
{
	const LV2_Atom_Sequence a = {
		{ forge->Sequence, sizeof(LV2_Atom_Sequence) - sizeof(LV2_Atom) },
		unit,
		0
	};
	LV2_Atom* atom = (LV2_Atom*)lv2_atom_forge_write(forge, &a, sizeof(a));
	return (LV2_Atom_Sequence*)lv2_atom_forge_push(forge, frame, atom);
}

/**
   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, passing
   the same @p parent parameter.  Note the returned LV2_Event is NOT an Atom.
*/
static inline LV2_Atom_Audio_Time*
lv2_atom_forge_audio_time(LV2_Atom_Forge* forge,
                          uint32_t        frames,
                          uint32_t        subframes)
{
	const LV2_Atom_Audio_Time a = { frames, subframes };
	return (LV2_Atom_Audio_Time*)lv2_atom_forge_write(forge, &a, sizeof(a));
}

/**
   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, passing
   the same @p parent parameter.  Note the returned LV2_Event is NOT an Atom.
*/
static inline double*
lv2_atom_forge_beat_time(LV2_Atom_Forge* forge,
                         double          beats)
{
	return (double*)lv2_atom_forge_write(forge, &beats, sizeof(beats));
}

#ifdef __cplusplus
}  /* extern "C" */
#endif

#endif  /* LV2_ATOM_FORGE_H */