Update version to 1.8.2 (minor fix)
[ctf.git] / common-trace-format-specification.txt
1 Common Trace Format (CTF) Specification (v1.8.2)
2
3 Mathieu Desnoyers, EfficiOS Inc.
4
5 The goal of the present document is to specify a trace format that suits the
6 needs of the embedded, telecom, high-performance and kernel communities. It is
7 based on the Common Trace Format Requirements (v1.4) document. It is designed to
8 allow traces to be natively generated by the Linux kernel, Linux user-space
9 applications written in C/C++, and hardware components. One major element of
10 CTF is the Trace Stream Description Language (TSDL) which flexibility
11 enables description of various binary trace stream layouts.
12
13 The latest version of this document can be found at:
14
15 git tree: git://git.efficios.com/ctf.git
16 gitweb: http://git.efficios.com/?p=ctf.git
17
18 A reference implementation of a library to read and write this trace format is
19 being implemented within the BabelTrace project, a converter between trace
20 formats. The development tree is available at:
21
22 git tree: git://git.efficios.com/babeltrace.git
23 gitweb: http://git.efficios.com/?p=babeltrace.git
24
25 The CE Workgroup of the Linux Foundation, Ericsson, and EfficiOS have
26 sponsored this work.
27
28
29 Table of Contents
30
31 1. Preliminary definitions
32 2. High-level representation of a trace
33 3. Event stream
34 4. Types
35 4.1 Basic types
36 4.1.1 Type inheritance
37 4.1.2 Alignment
38 4.1.3 Byte order
39 4.1.4 Size
40 4.1.5 Integers
41 4.1.6 GNU/C bitfields
42 4.1.7 Floating point
43 4.1.8 Enumerations
44 4.2 Compound types
45 4.2.1 Structures
46 4.2.2 Variants (Discriminated/Tagged Unions)
47 4.2.3 Arrays
48 4.2.4 Sequences
49 4.2.5 Strings
50 5. Event Packet Header
51 5.1 Event Packet Header Description
52 5.2 Event Packet Context Description
53 6. Event Structure
54 6.1 Event Header
55 6.1.1 Type 1 - Few event IDs
56 6.1.2 Type 2 - Many event IDs
57 6.2 Event Context
58 6.3 Event Payload
59 6.3.1 Padding
60 6.3.2 Alignment
61 7. Trace Stream Description Language (TSDL)
62 7.1 Meta-data
63 7.2 Declaration vs Definition
64 7.3 TSDL Scopes
65 7.3.1 Lexical Scope
66 7.3.2 Static and Dynamic Scopes
67 7.4 TSDL Examples
68 8. Clocks
69
70
71 1. Preliminary definitions
72
73 - Event Trace: An ordered sequence of events.
74 - Event Stream: An ordered sequence of events, containing a subset of the
75 trace event types.
76 - Event Packet: A sequence of physically contiguous events within an event
77 stream.
78 - Event: This is the basic entry in a trace. (aka: a trace record).
79 - An event identifier (ID) relates to the class (a type) of event within
80 an event stream.
81 e.g. event: irq_entry.
82 - An event (or event record) relates to a specific instance of an event
83 class.
84 e.g. event: irq_entry, at time X, on CPU Y
85 - Source Architecture: Architecture writing the trace.
86 - Reader Architecture: Architecture reading the trace.
87
88
89 2. High-level representation of a trace
90
91 A trace is divided into multiple event streams. Each event stream contains a
92 subset of the trace event types.
93
94 The final output of the trace, after its generation and optional transport over
95 the network, is expected to be either on permanent or temporary storage in a
96 virtual file system. Because each event stream is appended to while a trace is
97 being recorded, each is associated with a distinct set of files for
98 output. Therefore, a stored trace can be represented as a directory
99 containing zero, one or more files per stream.
100
101 Meta-data description associated with the trace contains information on
102 trace event types expressed in the Trace Stream Description Language
103 (TSDL). This language describes:
104
105 - Trace version.
106 - Types available.
107 - Per-trace event header description.
108 - Per-stream event header description.
109 - Per-stream event context description.
110 - Per-event
111 - Event type to stream mapping.
112 - Event type to name mapping.
113 - Event type to ID mapping.
114 - Event context description.
115 - Event fields description.
116
117
118 3. Event stream
119
120 An event stream can be divided into contiguous event packets of variable
121 size. An event packet can contain a certain amount of padding at the
122 end. The stream header is repeated at the beginning of each event
123 packet. The rationale for the event stream design choices is explained
124 in Appendix B. Stream Header Rationale.
125
126 The event stream header will therefore be referred to as the "event packet
127 header" throughout the rest of this document.
128
129
130 4. Types
131
132 Types are organized as type classes. Each type class belong to either of two
133 kind of types: basic types or compound types.
134
135 4.1 Basic types
136
137 A basic type is a scalar type, as described in this section. It includes
138 integers, GNU/C bitfields, enumerations, and floating point values.
139
140 4.1.1 Type inheritance
141
142 Type specifications can be inherited to allow deriving types from a
143 type class. For example, see the uint32_t named type derived from the "integer"
144 type class below ("Integers" section). Types have a precise binary
145 representation in the trace. A type class has methods to read and write these
146 types, but must be derived into a type to be usable in an event field.
147
148 4.1.2 Alignment
149
150 We define "byte-packed" types as aligned on the byte size, namely 8-bit.
151 We define "bit-packed" types as following on the next bit, as defined by the
152 "Integers" section.
153
154 Each basic type must specify its alignment, in bits. Examples of
155 possible alignments are: bit-packed (align = 1), byte-packed (align =
156 8), or word-aligned (e.g. align = 32 or align = 64). The choice depends
157 on the architecture preference and compactness vs performance trade-offs
158 of the implementation. Architectures providing fast unaligned write
159 byte-packed basic types to save space, aligning each type on byte
160 boundaries (8-bit). Architectures with slow unaligned writes align types
161 on specific alignment values. If no specific alignment is declared for a
162 type, it is assumed to be bit-packed for integers with size not multiple
163 of 8 bits and for gcc bitfields. All other basic types are byte-packed
164 by default. It is however recommended to always specify the alignment
165 explicitly. Alignment values must be power of two. Compound types are
166 aligned as specified in their individual specification.
167
168 TSDL meta-data attribute representation of a specific alignment:
169
170 align = value; /* value in bits */
171
172 4.1.3 Byte order
173
174 By default, the native endianness of the source architecture is used.
175 Byte order can be overridden for a basic type by specifying a "byte_order"
176 attribute. Typical use-case is to specify the network byte order (big endian:
177 "be") to save data captured from the network into the trace without conversion.
178 If not specified, the byte order is native.
179
180 TSDL meta-data representation:
181
182 byte_order = native OR network OR be OR le; /* network and be are aliases */
183
184 4.1.4 Size
185
186 Type size, in bits, for integers and floats is that returned by "sizeof()" in C
187 multiplied by CHAR_BIT.
188 We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
189 to 8 bits for cross-endianness compatibility.
190
191 TSDL meta-data representation:
192
193 size = value; (value is in bits)
194
195 4.1.5 Integers
196
197 Signed integers are represented in two-complement. Integer alignment,
198 size, signedness and byte ordering are defined in the TSDL meta-data.
199 Integers aligned on byte size (8-bit) and with length multiple of byte
200 size (8-bit) correspond to the C99 standard integers. In addition,
201 integers with alignment and/or size that are _not_ a multiple of the
202 byte size are permitted; these correspond to the C99 standard bitfields,
203 with the added specification that the CTF integer bitfields have a fixed
204 binary representation. A MIT-licensed reference implementation of the
205 CTF portable bitfields is available at:
206
207 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
208
209 Binary representation of integers:
210
211 - On little and big endian:
212 - Within a byte, high bits correspond to an integer high bits, and low bits
213 correspond to low bits.
214 - On little endian:
215 - Integer across multiple bytes are placed from the less significant to the
216 most significant.
217 - Consecutive integers are placed from lower bits to higher bits (even within
218 a byte).
219 - On big endian:
220 - Integer across multiple bytes are placed from the most significant to the
221 less significant.
222 - Consecutive integers are placed from higher bits to lower bits (even within
223 a byte).
224
225 This binary representation is derived from the bitfield implementation in GCC
226 for little and big endian. However, contrary to what GCC does, integers can
227 cross units boundaries (no padding is required). Padding can be explicitly
228 added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
229
230 TSDL meta-data representation:
231
232 integer {
233 signed = true OR false; /* default false */
234 byte_order = native OR network OR be OR le; /* default native */
235 size = value; /* value in bits, no default */
236 align = value; /* value in bits */
237 /* based used for pretty-printing output, default: decimal. */
238 base = decimal OR dec OR OR d OR i OR u OR 10 OR hexadecimal OR hex OR x OR X OR p OR 16
239 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
240 /* character encoding, default: none */
241 encoding = none or UTF8 or ASCII;
242 }
243
244 Example of type inheritance (creation of a uint32_t named type):
245
246 typealias integer {
247 size = 32;
248 signed = false;
249 align = 32;
250 } := uint32_t;
251
252 Definition of a named 5-bit signed bitfield:
253
254 typealias integer {
255 size = 5;
256 signed = true;
257 align = 1;
258 } := int5_t;
259
260 The character encoding field can be used to specify that the integer
261 must be printed as a text character when read. e.g.:
262
263 typealias integer {
264 size = 8;
265 align = 8;
266 signed = false;
267 encoding = UTF8;
268 } := utf_char;
269
270
271 4.1.6 GNU/C bitfields
272
273 The GNU/C bitfields follow closely the integer representation, with a
274 particularity on alignment: if a bitfield cannot fit in the current unit, the
275 unit is padded and the bitfield starts at the following unit. The unit size is
276 defined by the size of the type "unit_type".
277
278 TSDL meta-data representation:
279
280 unit_type name:size;
281
282 As an example, the following structure declared in C compiled by GCC:
283
284 struct example {
285 short a:12;
286 short b:5;
287 };
288
289 The example structure is aligned on the largest element (short). The second
290 bitfield would be aligned on the next unit boundary, because it would not fit in
291 the current unit.
292
293 4.1.7 Floating point
294
295 The floating point values byte ordering is defined in the TSDL meta-data.
296
297 Floating point values follow the IEEE 754-2008 standard interchange formats.
298 Description of the floating point values include the exponent and mantissa size
299 in bits. Some requirements are imposed on the floating point values:
300
301 - FLT_RADIX must be 2.
302 - mant_dig is the number of digits represented in the mantissa. It is specified
303 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
304 LDBL_MANT_DIG as defined by <float.h>.
305 - exp_dig is the number of digits represented in the exponent. Given that
306 mant_dig is one bit more than its actual size in bits (leading 1 is not
307 needed) and also given that the sign bit always takes one bit, exp_dig can be
308 specified as:
309
310 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
311 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
312 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
313
314 TSDL meta-data representation:
315
316 floating_point {
317 exp_dig = value;
318 mant_dig = value;
319 byte_order = native OR network OR be OR le;
320 align = value;
321 }
322
323 Example of type inheritance:
324
325 typealias floating_point {
326 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
327 mant_dig = 24; /* FLT_MANT_DIG */
328 byte_order = native;
329 align = 32;
330 } := float;
331
332 TODO: define NaN, +inf, -inf behavior.
333
334 Bit-packed, byte-packed or larger alignments can be used for floating
335 point values, similarly to integers.
336
337 4.1.8 Enumerations
338
339 Enumerations are a mapping between an integer type and a table of strings. The
340 numerical representation of the enumeration follows the integer type specified
341 by the meta-data. The enumeration mapping table is detailed in the enumeration
342 description within the meta-data. The mapping table maps inclusive value
343 ranges (or single values) to strings. Instead of being limited to simple
344 "value -> string" mappings, these enumerations map
345 "[ start_value ... end_value ] -> string", which map inclusive ranges of
346 values to strings. An enumeration from the C language can be represented in
347 this format by having the same start_value and end_value for each element, which
348 is in fact a range of size 1. This single-value range is supported without
349 repeating the start and end values with the value = string declaration.
350
351 enum name : integer_type {
352 somestring = start_value1 ... end_value1,
353 "other string" = start_value2 ... end_value2,
354 yet_another_string, /* will be assigned to end_value2 + 1 */
355 "some other string" = value,
356 ...
357 };
358
359 If the values are omitted, the enumeration starts at 0 and increment of 1 for
360 each entry. An entry with omitted value that follows a range entry takes
361 as value the end_value of the previous range + 1:
362
363 enum name : unsigned int {
364 ZERO,
365 ONE,
366 TWO,
367 TEN = 10,
368 ELEVEN,
369 };
370
371 Overlapping ranges within a single enumeration are implementation defined.
372
373 A nameless enumeration can be declared as a field type or as part of a typedef:
374
375 enum : integer_type {
376 ...
377 }
378
379 Enumerations omitting the container type ": integer_type" use the "int"
380 type (for compatibility with C99). The "int" type must be previously
381 declared. E.g.:
382
383 typealias integer { size = 32; align = 32; signed = true } := int;
384
385 enum {
386 ...
387 }
388
389
390 4.2 Compound types
391
392 Compound are aggregation of type declarations. Compound types include
393 structures, variant, arrays, sequences, and strings.
394
395 4.2.1 Structures
396
397 Structures are aligned on the largest alignment required by basic types
398 contained within the structure. (This follows the ISO/C standard for structures)
399
400 TSDL meta-data representation of a named structure:
401
402 struct name {
403 field_type field_name;
404 field_type field_name;
405 ...
406 };
407
408 Example:
409
410 struct example {
411 integer { /* Nameless type */
412 size = 16;
413 signed = true;
414 align = 16;
415 } first_field_name;
416 uint64_t second_field_name; /* Named type declared in the meta-data */
417 };
418
419 The fields are placed in a sequence next to each other. They each
420 possess a field name, which is a unique identifier within the structure.
421 The identifier is not allowed to use any reserved keyword
422 (see Section C.1.2). Replacing reserved keywords with
423 underscore-prefixed field names is recommended. Fields starting with an
424 underscore should have their leading underscore removed by the CTF trace
425 readers.
426
427 A nameless structure can be declared as a field type or as part of a typedef:
428
429 struct {
430 ...
431 }
432
433 Alignment for a structure compound type can be forced to a minimum value
434 by adding an "align" specifier after the declaration of a structure
435 body. This attribute is read as: align(value). The value is specified in
436 bits. The structure will be aligned on the maximum value between this
437 attribute and the alignment required by the basic types contained within
438 the structure. e.g.
439
440 struct {
441 ...
442 } align(32)
443
444 4.2.2 Variants (Discriminated/Tagged Unions)
445
446 A CTF variant is a selection between different types. A CTF variant must
447 always be defined within the scope of a structure or within fields
448 contained within a structure (defined recursively). A "tag" enumeration
449 field must appear in either the same static scope, prior to the variant
450 field (in field declaration order), in an upper static scope , or in an
451 upper dynamic scope (see Section 7.3.2). The type selection is indicated
452 by the mapping from the enumeration value to the string used as variant
453 type selector. The field to use as tag is specified by the "tag_field",
454 specified between "< >" after the "variant" keyword for unnamed
455 variants, and after "variant name" for named variants.
456
457 The alignment of the variant is the alignment of the type as selected by
458 the tag value for the specific instance of the variant. The size of the
459 variant is the size as selected by the tag value for the specific
460 instance of the variant.
461
462 The alignment of the type containing the variant is independent of the
463 variant alignment. For instance, if a structure contains two fields, a
464 32-bit integer, aligned on 32 bits, and a variant, which contains two
465 choices: either a 32-bit field, aligned on 32 bits, or a 64-bit field,
466 aligned on 64 bits, the alignment of the outmost structure will be
467 32-bit (the alignment of its largest field, disregarding the alignment
468 of the variant). The alignment of the variant will depend on the
469 selector: if the variant's 32-bit field is selected, its alignment will
470 be 32-bit, or 64-bit otherwise. It is important to note that variants
471 are specifically tailored for compactness in a stream. Therefore, the
472 relative offsets of compound type fields can vary depending on
473 the offset at which the compound type starts if it contains a variant
474 that itself contains a type with alignment larger than the largest field
475 contained within the compound type. This is caused by the fact that the
476 compound type may contain the enumeration that select the variant's
477 choice, and therefore the alignment to be applied to the compound type
478 cannot be determined before encountering the enumeration.
479
480 Each variant type selector possess a field name, which is a unique
481 identifier within the variant. The identifier is not allowed to use any
482 reserved keyword (see Section C.1.2). Replacing reserved keywords with
483 underscore-prefixed field names is recommended. Fields starting with an
484 underscore should have their leading underscore removed by the CTF trace
485 readers.
486
487
488 A named variant declaration followed by its definition within a structure
489 declaration:
490
491 variant name {
492 field_type sel1;
493 field_type sel2;
494 field_type sel3;
495 ...
496 };
497
498 struct {
499 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
500 ...
501 variant name <tag_field> v;
502 }
503
504 An unnamed variant definition within a structure is expressed by the following
505 TSDL meta-data:
506
507 struct {
508 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
509 ...
510 variant <tag_field> {
511 field_type sel1;
512 field_type sel2;
513 field_type sel3;
514 ...
515 } v;
516 }
517
518 Example of a named variant within a sequence that refers to a single tag field:
519
520 variant example {
521 uint32_t a;
522 uint64_t b;
523 short c;
524 };
525
526 struct {
527 enum : uint2_t { a, b, c } choice;
528 unsigned int seqlen;
529 variant example <choice> v[seqlen];
530 }
531
532 Example of an unnamed variant:
533
534 struct {
535 enum : uint2_t { a, b, c, d } choice;
536 /* Unrelated fields can be added between the variant and its tag */
537 int32_t somevalue;
538 variant <choice> {
539 uint32_t a;
540 uint64_t b;
541 short c;
542 struct {
543 unsigned int field1;
544 uint64_t field2;
545 } d;
546 } s;
547 }
548
549 Example of an unnamed variant within an array:
550
551 struct {
552 enum : uint2_t { a, b, c } choice;
553 variant <choice> {
554 uint32_t a;
555 uint64_t b;
556 short c;
557 } v[10];
558 }
559
560 Example of a variant type definition within a structure, where the defined type
561 is then declared within an array of structures. This variant refers to a tag
562 located in an upper static scope. This example clearly shows that a variant
563 type definition referring to the tag "x" uses the closest preceding field from
564 the static scope of the type definition.
565
566 struct {
567 enum : uint2_t { a, b, c, d } x;
568
569 typedef variant <x> { /*
570 * "x" refers to the preceding "x" enumeration in the
571 * static scope of the type definition.
572 */
573 uint32_t a;
574 uint64_t b;
575 short c;
576 } example_variant;
577
578 struct {
579 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
580 example_variant v; /*
581 * "v" uses the "enum : uint2_t { a, b, c, d }"
582 * tag.
583 */
584 } a[10];
585 }
586
587 4.2.3 Arrays
588
589 Arrays are fixed-length. Their length is declared in the type
590 declaration within the meta-data. They contain an array of "inner type"
591 elements, which can refer to any type not containing the type of the
592 array being declared (no circular dependency). The length is the number
593 of elements in an array.
594
595 TSDL meta-data representation of a named array:
596
597 typedef elem_type name[length];
598
599 A nameless array can be declared as a field type within a structure, e.g.:
600
601 uint8_t field_name[10];
602
603 Arrays are always aligned on their element alignment requirement.
604
605 4.2.4 Sequences
606
607 Sequences are dynamically-sized arrays. They refer to a a "length"
608 unsigned integer field, which must appear in either the same static scope,
609 prior to the sequence field (in field declaration order), in an upper
610 static scope, or in an upper dynamic scope (see Section 7.3.2). This
611 length field represents the number of elements in the sequence. The
612 sequence per se is an array of "inner type" elements.
613
614 TSDL meta-data representation for a sequence type definition:
615
616 struct {
617 unsigned int length_field;
618 typedef elem_type typename[length_field];
619 typename seq_field_name;
620 }
621
622 A sequence can also be declared as a field type, e.g.:
623
624 struct {
625 unsigned int length_field;
626 long seq_field_name[length_field];
627 }
628
629 Multiple sequences can refer to the same length field, and these length
630 fields can be in a different upper dynamic scope:
631
632 e.g., assuming the stream.event.header defines:
633
634 stream {
635 ...
636 id = 1;
637 event.header := struct {
638 uint16_t seq_len;
639 };
640 };
641
642 event {
643 ...
644 stream_id = 1;
645 fields := struct {
646 long seq_a[stream.event.header.seq_len];
647 char seq_b[stream.event.header.seq_len];
648 };
649 };
650
651 The sequence elements follow the "array" specifications.
652
653 4.2.5 Strings
654
655 Strings are an array of bytes of variable size and are terminated by a '\0'
656 "NULL" character. Their encoding is described in the TSDL meta-data. In
657 absence of encoding attribute information, the default encoding is
658 UTF-8.
659
660 TSDL meta-data representation of a named string type:
661
662 typealias string {
663 encoding = UTF8 OR ASCII;
664 } := name;
665
666 A nameless string type can be declared as a field type:
667
668 string field_name; /* Use default UTF8 encoding */
669
670 Strings are always aligned on byte size.
671
672 5. Event Packet Header
673
674 The event packet header consists of two parts: the "event packet header"
675 is the same for all streams of a trace. The second part, the "event
676 packet context", is described on a per-stream basis. Both are described
677 in the TSDL meta-data. The packets are aligned on architecture-page-sized
678 addresses.
679
680 Event packet header (all fields are optional, specified by TSDL meta-data):
681
682 - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
683 CTF packet. This magic number is optional, but when present, it should
684 come at the very beginning of the packet.
685 - Trace UUID, used to ensure the event packet match the meta-data used.
686 (note: we cannot use a meta-data checksum in every cases instead of a
687 UUID because meta-data can be appended to while tracing is active)
688 This field is optional.
689 - Stream ID, used as reference to stream description in meta-data.
690 This field is optional if there is only one stream description in the
691 meta-data, but becomes required if there are more than one stream in
692 the TSDL meta-data description.
693
694 Event packet context (all fields are optional, specified by TSDL meta-data):
695
696 - Event packet content size (in bits).
697 - Event packet size (in bits, includes padding).
698 - Event packet content checksum. Checksum excludes the event packet
699 header.
700 - Per-stream event packet sequence count (to deal with UDP packet loss). The
701 number of significant sequence counter bits should also be present, so
702 wrap-arounds are dealt with correctly.
703 - Time-stamp at the beginning and time-stamp at the end of the event packet.
704 Both timestamps are written in the packet header, but sampled respectively
705 while (or before) writing the first event and while (or after) writing the
706 last event in the packet. The inclusive range between these timestamps should
707 include all event timestamps assigned to events contained within the packet.
708 - Events discarded count
709 - Snapshot of a per-stream free-running counter, counting the number of
710 events discarded that were supposed to be written in the stream after
711 the last event in the event packet.
712 * Note: producer-consumer buffer full condition can fill the current
713 event packet with padding so we know exactly where events have been
714 discarded. However, if the buffer full condition chooses not
715 to fill the current event packet with padding, all we know
716 about the timestamp range in which the events have been
717 discarded is that it is somewhere between the beginning and
718 the end of the packet.
719 - Lossless compression scheme used for the event packet content. Applied
720 directly to raw data. New types of compression can be added in following
721 versions of the format.
722 0: no compression scheme
723 1: bzip2
724 2: gzip
725 3: xz
726 - Cypher used for the event packet content. Applied after compression.
727 0: no encryption
728 1: AES
729 - Checksum scheme used for the event packet content. Applied after encryption.
730 0: no checksum
731 1: md5
732 2: sha1
733 3: crc32
734
735 5.1 Event Packet Header Description
736
737 The event packet header layout is indicated by the trace packet.header
738 field. Here is a recommended structure type for the packet header with
739 the fields typically expected (although these fields are each optional):
740
741 struct event_packet_header {
742 uint32_t magic;
743 uint8_t uuid[16];
744 uint32_t stream_id;
745 };
746
747 trace {
748 ...
749 packet.header := struct event_packet_header;
750 };
751
752 If the magic number is not present, tools such as "file" will have no
753 mean to discover the file type.
754
755 If the uuid is not present, no validation that the meta-data actually
756 corresponds to the stream is performed.
757
758 If the stream_id packet header field is missing, the trace can only
759 contain a single stream. Its "id" field can be left out, and its events
760 don't need to declare a "stream_id" field.
761
762
763 5.2 Event Packet Context Description
764
765 Event packet context example. These are declared within the stream declaration
766 in the meta-data. All these fields are optional. If the packet size field is
767 missing, the whole stream only contains a single packet. If the content
768 size field is missing, the packet is filled (no padding). The content
769 and packet sizes include all headers.
770
771 An example event packet context type:
772
773 struct event_packet_context {
774 uint64_t timestamp_begin;
775 uint64_t timestamp_end;
776 uint32_t checksum;
777 uint32_t stream_packet_count;
778 uint32_t events_discarded;
779 uint32_t cpu_id;
780 uint64_t/uint32_t/uint16_t content_size;
781 uint64_t/uint32_t/uint16_t packet_size;
782 uint8_t compression_scheme;
783 uint8_t encryption_scheme;
784 uint8_t checksum_scheme;
785 };
786
787
788 6. Event Structure
789
790 The overall structure of an event is:
791
792 1 - Stream Packet Context (as specified by the stream meta-data)
793 2 - Event Header (as specified by the stream meta-data)
794 3 - Stream Event Context (as specified by the stream meta-data)
795 4 - Event Context (as specified by the event meta-data)
796 5 - Event Payload (as specified by the event meta-data)
797
798 This structure defines an implicit dynamic scoping, where variants
799 located in inner structures (those with a higher number in the listing
800 above) can refer to the fields of outer structures (with lower number in
801 the listing above). See Section 7.3 TSDL Scopes for more detail.
802
803 6.1 Event Header
804
805 Event headers can be described within the meta-data. We hereby propose, as an
806 example, two types of events headers. Type 1 accommodates streams with less than
807 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
808
809 One major factor can vary between streams: the number of event IDs assigned to
810 a stream. Luckily, this information tends to stay relatively constant (modulo
811 event registration while trace is being recorded), so we can specify different
812 representations for streams containing few event IDs and streams containing
813 many event IDs, so we end up representing the event ID and time-stamp as
814 densely as possible in each case.
815
816 The header is extended in the rare occasions where the information cannot be
817 represented in the ranges available in the standard event header. They are also
818 used in the rare occasions where the data required for a field could not be
819 collected: the flag corresponding to the missing field within the missing_fields
820 array is then set to 1.
821
822 Types uintX_t represent an X-bit unsigned integer, as declared with
823 either:
824
825 typealias integer { size = X; align = X; signed = false } := uintX_t;
826
827 or
828
829 typealias integer { size = X; align = 1; signed = false } := uintX_t;
830
831 6.1.1 Type 1 - Few event IDs
832
833 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
834 preference).
835 - Native architecture byte ordering.
836 - For "compact" selection
837 - Fixed size: 32 bits.
838 - For "extended" selection
839 - Size depends on the architecture and variant alignment.
840
841 struct event_header_1 {
842 /*
843 * id: range: 0 - 30.
844 * id 31 is reserved to indicate an extended header.
845 */
846 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
847 variant <id> {
848 struct {
849 uint27_t timestamp;
850 } compact;
851 struct {
852 uint32_t id; /* 32-bit event IDs */
853 uint64_t timestamp; /* 64-bit timestamps */
854 } extended;
855 } v;
856 } align(32); /* or align(8) */
857
858
859 6.1.2 Type 2 - Many event IDs
860
861 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
862 preference).
863 - Native architecture byte ordering.
864 - For "compact" selection
865 - Size depends on the architecture and variant alignment.
866 - For "extended" selection
867 - Size depends on the architecture and variant alignment.
868
869 struct event_header_2 {
870 /*
871 * id: range: 0 - 65534.
872 * id 65535 is reserved to indicate an extended header.
873 */
874 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
875 variant <id> {
876 struct {
877 uint32_t timestamp;
878 } compact;
879 struct {
880 uint32_t id; /* 32-bit event IDs */
881 uint64_t timestamp; /* 64-bit timestamps */
882 } extended;
883 } v;
884 } align(16); /* or align(8) */
885
886
887 6.2 Event Context
888
889 The event context contains information relative to the current event.
890 The choice and meaning of this information is specified by the TSDL
891 stream and event meta-data descriptions. The stream context is applied
892 to all events within the stream. The stream context structure follows
893 the event header. The event context is applied to specific events. Its
894 structure follows the stream context structure.
895
896 An example of stream-level event context is to save the event payload size with
897 each event, or to save the current PID with each event. These are declared
898 within the stream declaration within the meta-data:
899
900 stream {
901 ...
902 event.context := struct {
903 uint pid;
904 uint16_t payload_size;
905 };
906 };
907
908 An example of event-specific event context is to declare a bitmap of missing
909 fields, only appended after the stream event context if the extended event
910 header is selected. NR_FIELDS is the number of fields within the event (a
911 numeric value).
912
913 event {
914 context = struct {
915 variant <id> {
916 struct { } compact;
917 struct {
918 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
919 } extended;
920 } v;
921 };
922 ...
923 }
924
925 6.3 Event Payload
926
927 An event payload contains fields specific to a given event type. The fields
928 belonging to an event type are described in the event-specific meta-data
929 within a structure type.
930
931 6.3.1 Padding
932
933 No padding at the end of the event payload. This differs from the ISO/C standard
934 for structures, but follows the CTF standard for structures. In a trace, even
935 though it makes sense to align the beginning of a structure, it really makes no
936 sense to add padding at the end of the structure, because structures are usually
937 not followed by a structure of the same type.
938
939 This trick can be done by adding a zero-length "end" field at the end of the C
940 structures, and by using the offset of this field rather than using sizeof()
941 when calculating the size of a structure (see Appendix "A. Helper macros").
942
943 6.3.2 Alignment
944
945 The event payload is aligned on the largest alignment required by types
946 contained within the payload. (This follows the ISO/C standard for structures)
947
948
949 7. Trace Stream Description Language (TSDL)
950
951 The Trace Stream Description Language (TSDL) allows expression of the
952 binary trace streams layout in a C99-like Domain Specific Language
953 (DSL).
954
955
956 7.1 Meta-data
957
958 The trace stream layout description is located in the trace meta-data.
959 The meta-data is itself located in a stream identified by its name:
960 "metadata".
961
962 The meta-data description can be expressed in two different formats:
963 text-only and packet-based. The text-only description facilitates
964 generation of meta-data and provides a convenient way to enter the
965 meta-data information by hand. The packet-based meta-data provides the
966 CTF stream packet facilities (checksumming, compression, encryption,
967 network-readiness) for meta-data stream generated and transported by a
968 tracer.
969
970 The text-only meta-data file is a plain-text TSDL description. This file
971 must begin with the following characters to identify the file as a CTF
972 TSDL text-based metadata file (without the double-quotes) :
973
974 "/* CTF"
975
976 It must be followed by a space, and the version of the specification
977 followed by the CTF trace, e.g.:
978
979 " 1.8"
980
981 These characters allow automated discovery of file type and CTF
982 specification version. They are interpreted as a the beginning of a
983 comment by the TSDL metadata parser. The comment can be continued to
984 contain extra commented characters before it is closed.
985
986 The packet-based meta-data is made of "meta-data packets", which each
987 start with a meta-data packet header. The packet-based meta-data
988 description is detected by reading the magic number "0x75D11D57" at the
989 beginning of the file. This magic number is also used to detect the
990 endianness of the architecture by trying to read the CTF magic number
991 and its counterpart in reversed endianness. The events within the
992 meta-data stream have no event header nor event context. Each event only
993 contains a special "sequence" payload, which is a sequence of bits which
994 length is implicitly calculated by using the
995 "trace.packet.header.content_size" field, minus the packet header size.
996 The formatting of this sequence of bits is a plain-text representation
997 of the TSDL description. Each meta-data packet start with a special
998 packet header, specific to the meta-data stream, which contains,
999 exactly:
1000
1001 struct metadata_packet_header {
1002 uint32_t magic; /* 0x75D11D57 */
1003 uint8_t uuid[16]; /* Unique Universal Identifier */
1004 uint32_t checksum; /* 0 if unused */
1005 uint32_t content_size; /* in bits */
1006 uint32_t packet_size; /* in bits */
1007 uint8_t compression_scheme; /* 0 if unused */
1008 uint8_t encryption_scheme; /* 0 if unused */
1009 uint8_t checksum_scheme; /* 0 if unused */
1010 uint8_t major; /* CTF spec version major number */
1011 uint8_t minor; /* CTF spec version minor number */
1012 };
1013
1014 The packet-based meta-data can be converted to a text-only meta-data by
1015 concatenating all the strings it contains.
1016
1017 In the textual representation of the meta-data, the text contained
1018 within "/*" and "*/", as well as within "//" and end of line, are
1019 treated as comments. Boolean values can be represented as true, TRUE,
1020 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
1021 meta-data description, the trace UUID is represented as a string of
1022 hexadecimal digits and dashes "-". In the event packet header, the trace
1023 UUID is represented as an array of bytes.
1024
1025
1026 7.2 Declaration vs Definition
1027
1028 A declaration associates a layout to a type, without specifying where
1029 this type is located in the event structure hierarchy (see Section 6).
1030 This therefore includes typedef, typealias, as well as all type
1031 specifiers. In certain circumstances (typedef, structure field and
1032 variant field), a declaration is followed by a declarator, which specify
1033 the newly defined type name (for typedef), or the field name (for
1034 declarations located within structure and variants). Array and sequence,
1035 declared with square brackets ("[" "]"), are part of the declarator,
1036 similarly to C99. The enumeration base type is specified by
1037 ": enum_base", which is part of the type specifier. The variant tag
1038 name, specified between "<" ">", is also part of the type specifier.
1039
1040 A definition associates a type to a location in the event structure
1041 hierarchy (see Section 6). This association is denoted by ":=", as shown
1042 in Section 7.3.
1043
1044
1045 7.3 TSDL Scopes
1046
1047 TSDL uses three different types of scoping: a lexical scope is used for
1048 declarations and type definitions, and static and dynamic scopes are
1049 used for variants references to tag fields (with relative and absolute
1050 path lookups) and for sequence references to length fields.
1051
1052 7.3.1 Lexical Scope
1053
1054 Each of "trace", "env", "stream", "event", "struct" and "variant" have
1055 their own nestable declaration scope, within which types can be declared
1056 using "typedef" and "typealias". A root declaration scope also contains
1057 all declarations located outside of any of the aforementioned
1058 declarations. An inner declaration scope can refer to type declared
1059 within its container lexical scope prior to the inner declaration scope.
1060 Redefinition of a typedef or typealias is not valid, although hiding an
1061 upper scope typedef or typealias is allowed within a sub-scope.
1062
1063 7.3.2 Static and Dynamic Scopes
1064
1065 A local static scope consists in the scope generated by the declaration
1066 of fields within a compound type. A static scope is a local static scope
1067 augmented with the nested sub-static-scopes it contains.
1068
1069 A dynamic scope consists in the static scope augmented with the
1070 implicit event structure definition hierarchy presented at Section 6.
1071
1072 Multiple declarations of the same field name within a local static scope
1073 is not valid. It is however valid to re-use the same field name in
1074 different local scopes.
1075
1076 Nested static and dynamic scopes form lookup paths. These are used for
1077 variant tag and sequence length references. They are used at the variant
1078 and sequence definition site to look up the location of the tag field
1079 associated with a variant, and to lookup up the location of the length
1080 field associated with a sequence.
1081
1082 Variants and sequences can refer to a tag field either using a relative
1083 path or an absolute path. The relative path is relative to the scope in
1084 which the variant or sequence performing the lookup is located.
1085 Relative paths are only allowed to lookup within the same static scope,
1086 which includes its nested static scopes. Lookups targeting parent static
1087 scopes need to be performed with an absolute path.
1088
1089 Absolute path lookups use the full path including the dynamic scope
1090 followed by a "." and then the static scope. Therefore, variants (or
1091 sequences) in lower levels in the dynamic scope (e.g. event context) can
1092 refer to a tag (or length) field located in upper levels (e.g. in the
1093 event header) by specifying, in this case, the associated tag with
1094 <stream.event.header.field_name>. This allows, for instance, the event
1095 context to define a variant referring to the "id" field of the event
1096 header as selector.
1097
1098 The dynamic scope prefixes are thus:
1099
1100 - Trace Environment: <env. >,
1101 - Trace Packet Header: <trace.packet.header. >,
1102 - Stream Packet Context: <stream.packet.context. >,
1103 - Event Header: <stream.event.header. >,
1104 - Stream Event Context: <stream.event.context. >,
1105 - Event Context: <event.context. >,
1106 - Event Payload: <event.fields. >.
1107
1108
1109 The target dynamic scope must be specified explicitly when referring to
1110 a field outside of the static scope (absolute scope reference). No
1111 conflict can occur between relative and dynamic paths, because the
1112 keywords "trace", "stream", and "event" are reserved, and thus
1113 not permitted as field names. It is recommended that field names
1114 clashing with CTF and C99 reserved keywords use an underscore prefix to
1115 eliminate the risk of generating a description containing an invalid
1116 field name. Consequently, fields starting with an underscore should have
1117 their leading underscore removed by the CTF trace readers.
1118
1119
1120 The information available in the dynamic scopes can be thought of as the
1121 current tracing context. At trace production, information about the
1122 current context is saved into the specified scope field levels. At trace
1123 consumption, for each event, the current trace context is therefore
1124 readable by accessing the upper dynamic scopes.
1125
1126
1127 7.4 TSDL Examples
1128
1129 The grammar representing the TSDL meta-data is presented in Appendix C.
1130 TSDL Grammar. This section presents a rather lighter reading that
1131 consists in examples of TSDL meta-data, with template values.
1132
1133 The stream "id" can be left out if there is only one stream in the
1134 trace. The event "id" field can be left out if there is only one event
1135 in a stream.
1136
1137 trace {
1138 major = value; /* CTF spec version major number */
1139 minor = value; /* CTF spec version minor number */
1140 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1141 byte_order = be OR le; /* Endianness (required) */
1142 packet.header := struct {
1143 uint32_t magic;
1144 uint8_t uuid[16];
1145 uint32_t stream_id;
1146 };
1147 };
1148
1149 /*
1150 * The "env" (environment) scope contains assignment expressions. The
1151 * field names and content are implementation-defined.
1152 */
1153 env {
1154 pid = value; /* example */
1155 proc_name = "name"; /* example */
1156 ...
1157 };
1158
1159 stream {
1160 id = stream_id;
1161 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1162 event.header := event_header_1 OR event_header_2;
1163 event.context := struct {
1164 ...
1165 };
1166 packet.context := struct {
1167 ...
1168 };
1169 };
1170
1171 event {
1172 name = "event_name";
1173 id = value; /* Numeric identifier within the stream */
1174 stream_id = stream_id;
1175 loglevel = value;
1176 model.emf.uri = "string";
1177 context := struct {
1178 ...
1179 };
1180 fields := struct {
1181 ...
1182 };
1183 };
1184
1185 /* More detail on types in section 4. Types */
1186
1187 /*
1188 * Named types:
1189 *
1190 * Type declarations behave similarly to the C standard.
1191 */
1192
1193 typedef aliased_type_specifiers new_type_declarators;
1194
1195 /* e.g.: typedef struct example new_type_name[10]; */
1196
1197 /*
1198 * typealias
1199 *
1200 * The "typealias" declaration can be used to give a name (including
1201 * pointer declarator specifier) to a type. It should also be used to
1202 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1203 * Typealias is a superset of "typedef": it also allows assignment of a
1204 * simple variable identifier to a type.
1205 */
1206
1207 typealias type_class {
1208 ...
1209 } := type_specifiers type_declarator;
1210
1211 /*
1212 * e.g.:
1213 * typealias integer {
1214 * size = 32;
1215 * align = 32;
1216 * signed = false;
1217 * } := struct page *;
1218 *
1219 * typealias integer {
1220 * size = 32;
1221 * align = 32;
1222 * signed = true;
1223 * } := int;
1224 */
1225
1226 struct name {
1227 ...
1228 };
1229
1230 variant name {
1231 ...
1232 };
1233
1234 enum name : integer_type {
1235 ...
1236 };
1237
1238
1239 /*
1240 * Unnamed types, contained within compound type fields, typedef or typealias.
1241 */
1242
1243 struct {
1244 ...
1245 }
1246
1247 struct {
1248 ...
1249 } align(value)
1250
1251 variant {
1252 ...
1253 }
1254
1255 enum : integer_type {
1256 ...
1257 }
1258
1259 typedef type new_type[length];
1260
1261 struct {
1262 type field_name[length];
1263 }
1264
1265 typedef type new_type[length_type];
1266
1267 struct {
1268 type field_name[length_type];
1269 }
1270
1271 integer {
1272 ...
1273 }
1274
1275 floating_point {
1276 ...
1277 }
1278
1279 struct {
1280 integer_type field_name:size; /* GNU/C bitfield */
1281 }
1282
1283 struct {
1284 string field_name;
1285 }
1286
1287
1288 8. Clocks
1289
1290 Clock metadata allows to describe the clock topology of the system, as
1291 well as to detail each clock parameter. In absence of clock description,
1292 it is assumed that all fields named "timestamp" use the same clock
1293 source, which increments once per nanosecond.
1294
1295 Describing a clock and how it is used by streams is threefold: first,
1296 the clock and clock topology should be described in a "clock"
1297 description block, e.g.:
1298
1299 clock {
1300 name = cycle_counter_sync;
1301 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
1302 description = "Cycle counter synchronized across CPUs";
1303 freq = 1000000000; /* frequency, in Hz */
1304 /* precision in seconds is: 1000 * (1/freq) */
1305 precision = 1000;
1306 /*
1307 * clock value offset from Epoch is:
1308 * offset_s + (offset * (1/freq))
1309 */
1310 offset_s = 1326476837;
1311 offset = 897235420;
1312 absolute = FALSE;
1313 };
1314
1315 The mandatory "name" field specifies the name of the clock identifier,
1316 which can later be used as a reference. The optional field "uuid" is the
1317 unique identifier of the clock. It can be used to correlate different
1318 traces that use the same clock. An optional textual description string
1319 can be added with the "description" field. The "freq" field is the
1320 initial frequency of the clock, in Hz. If the "freq" field is not
1321 present, the frequency is assumed to be 1000000000 (providing clock
1322 increment of 1 ns). The optional "precision" field details the
1323 uncertainty on the clock measurements, in (1/freq) units. The "offset_s"
1324 and "offset" fields indicate the offset from POSIX.1 Epoch, 1970-01-01
1325 00:00:00 +0000 (UTC), to the zero of value of the clock. The "offset_s"
1326 field is in seconds. The "offset" field is in (1/freq) units. If any of
1327 the "offset_s" or "offset" field is not present, it is assigned the 0
1328 value. The field "absolute" is TRUE if the clock is a global reference
1329 across different clock uuid (e.g. NTP time). Otherwise, "absolute" is
1330 FALSE, and the clock can be considered as synchronized only with other
1331 clocks that have the same uuid.
1332
1333
1334 Secondly, a reference to this clock should be added within an integer
1335 type:
1336
1337 typealias integer {
1338 size = 64; align = 1; signed = false;
1339 map = clock.cycle_counter_sync.value;
1340 } := uint64_ccnt_t;
1341
1342 Thirdly, stream declarations can reference the clock they use as a
1343 time-stamp source:
1344
1345 struct packet_context {
1346 uint64_ccnt_t ccnt_begin;
1347 uint64_ccnt_t ccnt_end;
1348 /* ... */
1349 };
1350
1351 stream {
1352 /* ... */
1353 event.header := struct {
1354 uint64_ccnt_t timestamp;
1355 /* ... */
1356 }
1357 packet.context := struct packet_context;
1358 };
1359
1360 For a N-bit integer type referring to a clock, if the integer overflows
1361 compared to the N low order bits of the clock prior value, then it is
1362 assumed that one, and only one, overflow occurred. It is therefore
1363 important that events encoding time on a small number of bits happen
1364 frequently enough to detect when more than one N-bit overflow occurs.
1365
1366 In a packet context, clock field names ending with "_begin" and "_end"
1367 have a special meaning: this refers to the time-stamps at, respectively,
1368 the beginning and the end of each packet.
1369
1370
1371 A. Helper macros
1372
1373 The two following macros keep track of the size of a GNU/C structure without
1374 padding at the end by placing HEADER_END as the last field. A one byte end field
1375 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1376 that this does not affect the effective structure size, which should always be
1377 calculated with the header_sizeof() helper.
1378
1379 #define HEADER_END char end_field
1380 #define header_sizeof(type) offsetof(typeof(type), end_field)
1381
1382
1383 B. Stream Header Rationale
1384
1385 An event stream is divided in contiguous event packets of variable size. These
1386 subdivisions allow the trace analyzer to perform a fast binary search by time
1387 within the stream (typically requiring to index only the event packet headers)
1388 without reading the whole stream. These subdivisions have a variable size to
1389 eliminate the need to transfer the event packet padding when partially filled
1390 event packets must be sent when streaming a trace for live viewing/analysis.
1391 An event packet can contain a certain amount of padding at the end. Dividing
1392 streams into event packets is also useful for network streaming over UDP and
1393 flight recorder mode tracing (a whole event packet can be swapped out of the
1394 buffer atomically for reading).
1395
1396 The stream header is repeated at the beginning of each event packet to allow
1397 flexibility in terms of:
1398
1399 - streaming support,
1400 - allowing arbitrary buffers to be discarded without making the trace
1401 unreadable,
1402 - allow UDP packet loss handling by either dealing with missing event packet
1403 or asking for re-transmission.
1404 - transparently support flight recorder mode,
1405 - transparently support crash dump.
1406
1407
1408 C. TSDL Grammar
1409
1410 /*
1411 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1412 *
1413 * Inspired from the C99 grammar:
1414 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1415 * and c++1x grammar (draft)
1416 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1417 *
1418 * Specialized for CTF needs by including only constant and declarations from
1419 * C99 (excluding function declarations), and by adding support for variants,
1420 * sequences and CTF-specific specifiers. Enumeration container types
1421 * semantic is inspired from c++1x enum-base.
1422 */
1423
1424 1) Lexical grammar
1425
1426 1.1) Lexical elements
1427
1428 token:
1429 keyword
1430 identifier
1431 constant
1432 string-literal
1433 punctuator
1434
1435 1.2) Keywords
1436
1437 keyword: is one of
1438
1439 align
1440 const
1441 char
1442 clock
1443 double
1444 enum
1445 env
1446 event
1447 floating_point
1448 float
1449 integer
1450 int
1451 long
1452 short
1453 signed
1454 stream
1455 string
1456 struct
1457 trace
1458 typealias
1459 typedef
1460 unsigned
1461 variant
1462 void
1463 _Bool
1464 _Complex
1465 _Imaginary
1466
1467
1468 1.3) Identifiers
1469
1470 identifier:
1471 identifier-nondigit
1472 identifier identifier-nondigit
1473 identifier digit
1474
1475 identifier-nondigit:
1476 nondigit
1477 universal-character-name
1478 any other implementation-defined characters
1479
1480 nondigit:
1481 _
1482 [a-zA-Z] /* regular expression */
1483
1484 digit:
1485 [0-9] /* regular expression */
1486
1487 1.4) Universal character names
1488
1489 universal-character-name:
1490 \u hex-quad
1491 \U hex-quad hex-quad
1492
1493 hex-quad:
1494 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1495
1496 1.5) Constants
1497
1498 constant:
1499 integer-constant
1500 enumeration-constant
1501 character-constant
1502
1503 integer-constant:
1504 decimal-constant integer-suffix-opt
1505 octal-constant integer-suffix-opt
1506 hexadecimal-constant integer-suffix-opt
1507
1508 decimal-constant:
1509 nonzero-digit
1510 decimal-constant digit
1511
1512 octal-constant:
1513 0
1514 octal-constant octal-digit
1515
1516 hexadecimal-constant:
1517 hexadecimal-prefix hexadecimal-digit
1518 hexadecimal-constant hexadecimal-digit
1519
1520 hexadecimal-prefix:
1521 0x
1522 0X
1523
1524 nonzero-digit:
1525 [1-9]
1526
1527 integer-suffix:
1528 unsigned-suffix long-suffix-opt
1529 unsigned-suffix long-long-suffix
1530 long-suffix unsigned-suffix-opt
1531 long-long-suffix unsigned-suffix-opt
1532
1533 unsigned-suffix:
1534 u
1535 U
1536
1537 long-suffix:
1538 l
1539 L
1540
1541 long-long-suffix:
1542 ll
1543 LL
1544
1545 enumeration-constant:
1546 identifier
1547 string-literal
1548
1549 character-constant:
1550 ' c-char-sequence '
1551 L' c-char-sequence '
1552
1553 c-char-sequence:
1554 c-char
1555 c-char-sequence c-char
1556
1557 c-char:
1558 any member of source charset except single-quote ('), backslash
1559 (\), or new-line character.
1560 escape-sequence
1561
1562 escape-sequence:
1563 simple-escape-sequence
1564 octal-escape-sequence
1565 hexadecimal-escape-sequence
1566 universal-character-name
1567
1568 simple-escape-sequence: one of
1569 \' \" \? \\ \a \b \f \n \r \t \v
1570
1571 octal-escape-sequence:
1572 \ octal-digit
1573 \ octal-digit octal-digit
1574 \ octal-digit octal-digit octal-digit
1575
1576 hexadecimal-escape-sequence:
1577 \x hexadecimal-digit
1578 hexadecimal-escape-sequence hexadecimal-digit
1579
1580 1.6) String literals
1581
1582 string-literal:
1583 " s-char-sequence-opt "
1584 L" s-char-sequence-opt "
1585
1586 s-char-sequence:
1587 s-char
1588 s-char-sequence s-char
1589
1590 s-char:
1591 any member of source charset except double-quote ("), backslash
1592 (\), or new-line character.
1593 escape-sequence
1594
1595 1.7) Punctuators
1596
1597 punctuator: one of
1598 [ ] ( ) { } . -> * + - < > : ; ... = ,
1599
1600
1601 2) Phrase structure grammar
1602
1603 primary-expression:
1604 identifier
1605 constant
1606 string-literal
1607 ( unary-expression )
1608
1609 postfix-expression:
1610 primary-expression
1611 postfix-expression [ unary-expression ]
1612 postfix-expression . identifier
1613 postfix-expressoin -> identifier
1614
1615 unary-expression:
1616 postfix-expression
1617 unary-operator postfix-expression
1618
1619 unary-operator: one of
1620 + -
1621
1622 assignment-operator:
1623 =
1624
1625 type-assignment-operator:
1626 :=
1627
1628 constant-expression-range:
1629 unary-expression ... unary-expression
1630
1631 2.2) Declarations:
1632
1633 declaration:
1634 declaration-specifiers declarator-list-opt ;
1635 ctf-specifier ;
1636
1637 declaration-specifiers:
1638 storage-class-specifier declaration-specifiers-opt
1639 type-specifier declaration-specifiers-opt
1640 type-qualifier declaration-specifiers-opt
1641
1642 declarator-list:
1643 declarator
1644 declarator-list , declarator
1645
1646 abstract-declarator-list:
1647 abstract-declarator
1648 abstract-declarator-list , abstract-declarator
1649
1650 storage-class-specifier:
1651 typedef
1652
1653 type-specifier:
1654 void
1655 char
1656 short
1657 int
1658 long
1659 float
1660 double
1661 signed
1662 unsigned
1663 _Bool
1664 _Complex
1665 _Imaginary
1666 struct-specifier
1667 variant-specifier
1668 enum-specifier
1669 typedef-name
1670 ctf-type-specifier
1671
1672 align-attribute:
1673 align ( unary-expression )
1674
1675 struct-specifier:
1676 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1677 struct identifier align-attribute-opt
1678
1679 struct-or-variant-declaration-list:
1680 struct-or-variant-declaration
1681 struct-or-variant-declaration-list struct-or-variant-declaration
1682
1683 struct-or-variant-declaration:
1684 specifier-qualifier-list struct-or-variant-declarator-list ;
1685 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1686 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1687 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1688
1689 specifier-qualifier-list:
1690 type-specifier specifier-qualifier-list-opt
1691 type-qualifier specifier-qualifier-list-opt
1692
1693 struct-or-variant-declarator-list:
1694 struct-or-variant-declarator
1695 struct-or-variant-declarator-list , struct-or-variant-declarator
1696
1697 struct-or-variant-declarator:
1698 declarator
1699 declarator-opt : unary-expression
1700
1701 variant-specifier:
1702 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1703 variant identifier variant-tag
1704
1705 variant-tag:
1706 < unary-expression >
1707
1708 enum-specifier:
1709 enum identifier-opt { enumerator-list }
1710 enum identifier-opt { enumerator-list , }
1711 enum identifier
1712 enum identifier-opt : declaration-specifiers { enumerator-list }
1713 enum identifier-opt : declaration-specifiers { enumerator-list , }
1714
1715 enumerator-list:
1716 enumerator
1717 enumerator-list , enumerator
1718
1719 enumerator:
1720 enumeration-constant
1721 enumeration-constant assignment-operator unary-expression
1722 enumeration-constant assignment-operator constant-expression-range
1723
1724 type-qualifier:
1725 const
1726
1727 declarator:
1728 pointer-opt direct-declarator
1729
1730 direct-declarator:
1731 identifier
1732 ( declarator )
1733 direct-declarator [ unary-expression ]
1734
1735 abstract-declarator:
1736 pointer-opt direct-abstract-declarator
1737
1738 direct-abstract-declarator:
1739 identifier-opt
1740 ( abstract-declarator )
1741 direct-abstract-declarator [ unary-expression ]
1742 direct-abstract-declarator [ ]
1743
1744 pointer:
1745 * type-qualifier-list-opt
1746 * type-qualifier-list-opt pointer
1747
1748 type-qualifier-list:
1749 type-qualifier
1750 type-qualifier-list type-qualifier
1751
1752 typedef-name:
1753 identifier
1754
1755 2.3) CTF-specific declarations
1756
1757 ctf-specifier:
1758 clock { ctf-assignment-expression-list-opt }
1759 event { ctf-assignment-expression-list-opt }
1760 stream { ctf-assignment-expression-list-opt }
1761 env { ctf-assignment-expression-list-opt }
1762 trace { ctf-assignment-expression-list-opt }
1763 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1764 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1765
1766 ctf-type-specifier:
1767 floating_point { ctf-assignment-expression-list-opt }
1768 integer { ctf-assignment-expression-list-opt }
1769 string { ctf-assignment-expression-list-opt }
1770 string
1771
1772 ctf-assignment-expression-list:
1773 ctf-assignment-expression ;
1774 ctf-assignment-expression-list ctf-assignment-expression ;
1775
1776 ctf-assignment-expression:
1777 unary-expression assignment-operator unary-expression
1778 unary-expression type-assignment-operator type-specifier
1779 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1780 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1781 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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