Add basic clock description
[ctf.git] / common-trace-format-specification.txt
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4dfca05b 1Common Trace Format (CTF) Specification (pre-v1.8)
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2
3Mathieu Desnoyers, EfficiOS Inc.
4
339a7dde 5The goal of the present document is to specify a trace format that suits the
cc089c3a 6needs of the embedded, telecom, high-performance and kernel communities. It is
5ba9f198 7based on the Common Trace Format Requirements (v1.4) document. It is designed to
cc089c3a 8allow traces to be natively generated by the Linux kernel, Linux user-space
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9applications written in C/C++, and hardware components. One major element of
10CTF is the Trace Stream Description Language (TSDL) which flexibility
11enables description of various binary trace stream layouts.
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12
13The 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
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17
18A reference implementation of a library to read and write this trace format is
19being implemented within the BabelTrace project, a converter between trace
20formats. 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
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25The CE Workgroup of the Linux Foundation, Ericsson, and EfficiOS have
26sponsored this work.
27
5ba9f198 28
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29Table of Contents
30
311. Preliminary definitions
322. High-level representation of a trace
333. Event stream
344. 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
444.2 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
505. Event Packet Header
51 5.1 Event Packet Header Description
52 5.2 Event Packet Context Description
536. 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
617. 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
37ab95c3 66 7.3.2 Static and Dynamic Scopes
beabf088 67 7.4 TSDL Examples
2fa70eba 688. Clocks
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69
70
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711. Preliminary definitions
72
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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.
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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
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80 an event stream.
81 e.g. event: irq_entry.
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82 - An event (or event record) relates to a specific instance of an event
83 class.
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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.
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87
88
892. High-level representation of a trace
90
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91A trace is divided into multiple event streams. Each event stream contains a
92subset of the trace event types.
5ba9f198 93
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94The final output of the trace, after its generation and optional transport over
95the network, is expected to be either on permanent or temporary storage in a
96virtual file system. Because each event stream is appended to while a trace is
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97being recorded, each is associated with a distinct set of files for
98output. Therefore, a stored trace can be represented as a directory
99containing zero, one or more files per stream.
5ba9f198 100
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101Meta-data description associated with the trace contains information on
102trace event types expressed in the Trace Stream Description Language
103(TSDL). This language describes:
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104
105- Trace version.
106- Types available.
6672e9e1 107- Per-trace event header description.
3bf79539 108- Per-stream event header description.
6672e9e1 109- Per-stream event context description.
5ba9f198 110- Per-event
3bf79539 111 - Event type to stream mapping.
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112 - Event type to name mapping.
113 - Event type to ID mapping.
6672e9e1 114 - Event context description.
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115 - Event fields description.
116
117
3bf79539 1183. Event stream
5ba9f198 119
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120An event stream can be divided into contiguous event packets of variable
121size. These subdivisions have a variable size. An event packet can
122contain a certain amount of padding at the end. The stream header is
123repeated at the beginning of each event packet. The rationale for the
124event stream design choices is explained in Appendix B. Stream Header
125Rationale.
5ba9f198 126
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127The event stream header will therefore be referred to as the "event packet
128header" throughout the rest of this document.
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129
130
1314. Types
132
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133Types are organized as type classes. Each type class belong to either of two
134kind of types: basic types or compound types.
135
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1364.1 Basic types
137
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138A basic type is a scalar type, as described in this section. It includes
139integers, GNU/C bitfields, enumerations, and floating point values.
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140
1414.1.1 Type inheritance
142
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143Type specifications can be inherited to allow deriving types from a
144type class. For example, see the uint32_t named type derived from the "integer"
145type class below ("Integers" section). Types have a precise binary
146representation in the trace. A type class has methods to read and write these
147types, but must be derived into a type to be usable in an event field.
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148
1494.1.2 Alignment
150
151We define "byte-packed" types as aligned on the byte size, namely 8-bit.
152We define "bit-packed" types as following on the next bit, as defined by the
370eae99 153"Integers" section.
5ba9f198 154
6672e9e1 155Each basic type must specify its alignment, in bits. Examples of
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156possible alignments are: bit-packed (align = 1), byte-packed (align =
1578), or word-aligned (e.g. align = 32 or align = 64). The choice depends
158on the architecture preference and compactness vs performance trade-offs
159of the implementation. Architectures providing fast unaligned write
160byte-packed basic types to save space, aligning each type on byte
161boundaries (8-bit). Architectures with slow unaligned writes align types
162on specific alignment values. If no specific alignment is declared for a
163type, it is assumed to be bit-packed for integers with size not multiple
164of 8 bits and for gcc bitfields. All other basic types are byte-packed
165by default. It is however recommended to always specify the alignment
166explicitly. Alignment values must be power of two. Compound types are
167aligned as specified in their individual specification.
5ba9f198 168
6672e9e1 169TSDL meta-data attribute representation of a specific alignment:
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170
171 align = value; /* value in bits */
172
1734.1.3 Byte order
174
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175By default, the native endianness of the source architecture the trace is used.
176Byte order can be overridden for a basic type by specifying a "byte_order"
177attribute. Typical use-case is to specify the network byte order (big endian:
178"be") to save data captured from the network into the trace without conversion.
179If not specified, the byte order is native.
5ba9f198 180
6672e9e1 181TSDL meta-data representation:
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182
183 byte_order = native OR network OR be OR le; /* network and be are aliases */
184
1854.1.4 Size
186
187Type size, in bits, for integers and floats is that returned by "sizeof()" in C
188multiplied by CHAR_BIT.
189We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
190to 8 bits for cross-endianness compatibility.
191
6672e9e1 192TSDL meta-data representation:
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193
194 size = value; (value is in bits)
195
1964.1.5 Integers
197
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198Signed integers are represented in two-complement. Integer alignment,
199size, signedness and byte ordering are defined in the TSDL meta-data.
200Integers aligned on byte size (8-bit) and with length multiple of byte
201size (8-bit) correspond to the C99 standard integers. In addition,
202integers with alignment and/or size that are _not_ a multiple of the
203byte size are permitted; these correspond to the C99 standard bitfields,
204with the added specification that the CTF integer bitfields have a fixed
205binary representation. A MIT-licensed reference implementation of the
206CTF portable bitfields is available at:
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207
208 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
209
210Binary representation of integers:
211
212- On little and big endian:
213 - Within a byte, high bits correspond to an integer high bits, and low bits
214 correspond to low bits.
215- On little endian:
216 - Integer across multiple bytes are placed from the less significant to the
217 most significant.
218 - Consecutive integers are placed from lower bits to higher bits (even within
219 a byte).
220- On big endian:
221 - Integer across multiple bytes are placed from the most significant to the
222 less significant.
223 - Consecutive integers are placed from higher bits to lower bits (even within
224 a byte).
225
226This binary representation is derived from the bitfield implementation in GCC
227for little and big endian. However, contrary to what GCC does, integers can
6672e9e1 228cross units boundaries (no padding is required). Padding can be explicitly
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229added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
230
6672e9e1 231TSDL meta-data representation:
5ba9f198 232
80fd2569 233 integer {
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234 signed = true OR false; /* default false */
235 byte_order = native OR network OR be OR le; /* default native */
236 size = value; /* value in bits, no default */
237 align = value; /* value in bits */
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238 /* based used for pretty-printing output, default: decimal. */
239 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
240 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
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241 /* character encoding, default: none */
242 encoding = none or UTF8 or ASCII;
2152348f 243 }
5ba9f198 244
80fd2569 245Example of type inheritance (creation of a uint32_t named type):
5ba9f198 246
359894ac 247typealias integer {
9e4e34e9 248 size = 32;
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249 signed = false;
250 align = 32;
38b8da21 251} := uint32_t;
5ba9f198 252
80fd2569 253Definition of a named 5-bit signed bitfield:
5ba9f198 254
359894ac 255typealias integer {
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256 size = 5;
257 signed = true;
258 align = 1;
38b8da21 259} := int5_t;
5ba9f198 260
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261The character encoding field can be used to specify that the integer
262must be printed as a text character when read. e.g.:
263
264typealias integer {
265 size = 8;
266 align = 8;
267 signed = false;
268 encoding = UTF8;
269} := utf_char;
270
271
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2724.1.6 GNU/C bitfields
273
274The GNU/C bitfields follow closely the integer representation, with a
275particularity on alignment: if a bitfield cannot fit in the current unit, the
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276unit is padded and the bitfield starts at the following unit. The unit size is
277defined by the size of the type "unit_type".
5ba9f198 278
6672e9e1 279TSDL meta-data representation:
80fd2569 280
d674f4b8 281 unit_type name:size;
80fd2569 282
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283As an example, the following structure declared in C compiled by GCC:
284
285struct example {
286 short a:12;
287 short b:5;
288};
289
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290The example structure is aligned on the largest element (short). The second
291bitfield would be aligned on the next unit boundary, because it would not fit in
292the current unit.
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293
2944.1.7 Floating point
295
6672e9e1 296The floating point values byte ordering is defined in the TSDL meta-data.
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297
298Floating point values follow the IEEE 754-2008 standard interchange formats.
299Description of the floating point values include the exponent and mantissa size
300in bits. Some requirements are imposed on the floating point values:
301
302- FLT_RADIX must be 2.
303- mant_dig is the number of digits represented in the mantissa. It is specified
304 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
305 LDBL_MANT_DIG as defined by <float.h>.
306- exp_dig is the number of digits represented in the exponent. Given that
307 mant_dig is one bit more than its actual size in bits (leading 1 is not
308 needed) and also given that the sign bit always takes one bit, exp_dig can be
309 specified as:
310
311 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
312 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
313 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
314
6672e9e1 315TSDL meta-data representation:
5ba9f198 316
80fd2569 317floating_point {
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318 exp_dig = value;
319 mant_dig = value;
320 byte_order = native OR network OR be OR le;
321 align = value;
2152348f 322}
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323
324Example of type inheritance:
325
359894ac 326typealias floating_point {
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327 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
328 mant_dig = 24; /* FLT_MANT_DIG */
329 byte_order = native;
ec4404a7 330 align = 32;
38b8da21 331} := float;
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332
333TODO: define NaN, +inf, -inf behavior.
334
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335Bit-packed, byte-packed or larger alignments can be used for floating
336point values, similarly to integers.
337
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3384.1.8 Enumerations
339
340Enumerations are a mapping between an integer type and a table of strings. The
341numerical representation of the enumeration follows the integer type specified
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342by the meta-data. The enumeration mapping table is detailed in the enumeration
343description within the meta-data. The mapping table maps inclusive value
344ranges (or single values) to strings. Instead of being limited to simple
3bf79539 345"value -> string" mappings, these enumerations map
80fd2569 346"[ start_value ... end_value ] -> string", which map inclusive ranges of
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347values to strings. An enumeration from the C language can be represented in
348this format by having the same start_value and end_value for each element, which
349is in fact a range of size 1. This single-value range is supported without
4767a9e7 350repeating the start and end values with the value = string declaration.
80fd2569 351
a9b83695 352enum name : integer_type {
359894ac 353 somestring = start_value1 ... end_value1,
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354 "other string" = start_value2 ... end_value2,
355 yet_another_string, /* will be assigned to end_value2 + 1 */
356 "some other string" = value,
357 ...
358};
359
360If the values are omitted, the enumeration starts at 0 and increment of 1 for
361each entry:
362
a9b83695 363enum name : unsigned int {
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364 ZERO,
365 ONE,
366 TWO,
367 TEN = 10,
368 ELEVEN,
3bf79539 369};
5ba9f198 370
80fd2569 371Overlapping ranges within a single enumeration are implementation defined.
5ba9f198 372
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373A nameless enumeration can be declared as a field type or as part of a typedef:
374
a9b83695 375enum : integer_type {
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376 ...
377}
378
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379Enumerations omitting the container type ": integer_type" use the "int"
380type (for compatibility with C99). The "int" type must be previously
381declared. E.g.:
382
383typealias integer { size = 32; align = 32; signed = true } := int;
384
385enum {
386 ...
387}
388
1fad7a85 389
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3904.2 Compound types
391
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392Compound are aggregation of type declarations. Compound types include
393structures, variant, arrays, sequences, and strings.
394
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3954.2.1 Structures
396
397Structures are aligned on the largest alignment required by basic types
398contained within the structure. (This follows the ISO/C standard for structures)
399
6672e9e1 400TSDL meta-data representation of a named structure:
5ba9f198 401
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402struct name {
403 field_type field_name;
404 field_type field_name;
405 ...
406};
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407
408Example:
409
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410struct example {
411 integer { /* Nameless type */
412 size = 16;
413 signed = true;
414 align = 16;
415 } first_field_name;
6672e9e1 416 uint64_t second_field_name; /* Named type declared in the meta-data */
3bf79539 417};
5ba9f198 418
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419The fields are placed in a sequence next to each other. They each
420possess a field name, which is a unique identifier within the structure.
421The identifier is not allowed to use any reserved keyword
422(see Section C.1.2). Replacing reserved keywords with
423underscore-prefixed field names is recommended.
5ba9f198 424
2152348f 425A nameless structure can be declared as a field type or as part of a typedef:
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426
427struct {
428 ...
2152348f 429}
80fd2569 430
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431Alignment for a structure compound type can be forced to a minimum value
432by adding an "align" specifier after the declaration of a structure
433body. This attribute is read as: align(value). The value is specified in
434bits. The structure will be aligned on the maximum value between this
435attribute and the alignment required by the basic types contained within
436the structure. e.g.
437
438struct {
439 ...
440} align(32)
441
77a98c82 4424.2.2 Variants (Discriminated/Tagged Unions)
fcba70d4 443
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444A CTF variant is a selection between different types. A CTF variant must
445always be defined within the scope of a structure or within fields
446contained within a structure (defined recursively). A "tag" enumeration
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447field must appear in either the same static scope, prior to the variant
448field (in field declaration order), in an upper static scope , or in an
449upper dynamic scope (see Section 7.3.2). The type selection is indicated
450by the mapping from the enumeration value to the string used as variant
451type selector. The field to use as tag is specified by the "tag_field",
452specified between "< >" after the "variant" keyword for unnamed
453variants, and after "variant name" for named variants.
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454
455The alignment of the variant is the alignment of the type as selected by the tag
456value for the specific instance of the variant. The alignment of the type
457containing the variant is independent of the variant alignment. The size of the
458variant is the size as selected by the tag value for the specific instance of
459the variant.
460
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461Each variant type selector possess a field name, which is a unique
462identifier within the variant. The identifier is not allowed to use any
463reserved keyword (see Section C.1.2). Replacing reserved keywords with
464underscore-prefixed field names is recommended.
465
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466A named variant declaration followed by its definition within a structure
467declaration:
468
469variant name {
470 field_type sel1;
471 field_type sel2;
472 field_type sel3;
473 ...
474};
475
476struct {
a9b83695 477 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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478 ...
479 variant name <tag_field> v;
480}
481
482An unnamed variant definition within a structure is expressed by the following
6672e9e1 483TSDL meta-data:
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484
485struct {
a9b83695 486 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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487 ...
488 variant <tag_field> {
489 field_type sel1;
490 field_type sel2;
491 field_type sel3;
492 ...
493 } v;
494}
495
496Example of a named variant within a sequence that refers to a single tag field:
497
498variant example {
499 uint32_t a;
500 uint64_t b;
501 short c;
502};
503
504struct {
a9b83695 505 enum : uint2_t { a, b, c } choice;
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506 unsigned int seqlen;
507 variant example <choice> v[seqlen];
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508}
509
510Example of an unnamed variant:
511
512struct {
a9b83695 513 enum : uint2_t { a, b, c, d } choice;
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514 /* Unrelated fields can be added between the variant and its tag */
515 int32_t somevalue;
516 variant <choice> {
517 uint32_t a;
518 uint64_t b;
519 short c;
520 struct {
521 unsigned int field1;
522 uint64_t field2;
523 } d;
524 } s;
525}
526
527Example of an unnamed variant within an array:
528
529struct {
a9b83695 530 enum : uint2_t { a, b, c } choice;
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531 variant <choice> {
532 uint32_t a;
533 uint64_t b;
534 short c;
15850440 535 } v[10];
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536}
537
538Example of a variant type definition within a structure, where the defined type
539is then declared within an array of structures. This variant refers to a tag
37ab95c3 540located in an upper static scope. This example clearly shows that a variant
fcba70d4 541type definition referring to the tag "x" uses the closest preceding field from
37ab95c3 542the static scope of the type definition.
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543
544struct {
a9b83695 545 enum : uint2_t { a, b, c, d } x;
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546
547 typedef variant <x> { /*
548 * "x" refers to the preceding "x" enumeration in the
37ab95c3 549 * static scope of the type definition.
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550 */
551 uint32_t a;
552 uint64_t b;
553 short c;
554 } example_variant;
555
556 struct {
a9b83695 557 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
fcba70d4 558 example_variant v; /*
a9b83695 559 * "v" uses the "enum : uint2_t { a, b, c, d }"
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560 * tag.
561 */
562 } a[10];
563}
564
5654.2.3 Arrays
5ba9f198 566
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567Arrays are fixed-length. Their length is declared in the type
568declaration within the meta-data. They contain an array of "inner type"
569elements, which can refer to any type not containing the type of the
570array being declared (no circular dependency). The length is the number
571of elements in an array.
5ba9f198 572
6672e9e1 573TSDL meta-data representation of a named array:
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574
575typedef elem_type name[length];
5ba9f198 576
2152348f 577A nameless array can be declared as a field type within a structure, e.g.:
5ba9f198 578
2152348f 579 uint8_t field_name[10];
80fd2569 580
ec4404a7 581Arrays are always aligned on their element alignment requirement.
5ba9f198 582
fcba70d4 5834.2.4 Sequences
5ba9f198 584
1ab22b2a 585Sequences are dynamically-sized arrays. They refer to a a "length"
37ab95c3 586unsigned integer field, which must appear in either the same static scope,
1ab22b2a 587prior to the sequence field (in field declaration order), in an upper
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588static scope, or in an upper dynamic scope (see Section 7.3.2). This
589length field represents the number of elements in the sequence. The
590sequence per se is an array of "inner type" elements.
5ba9f198 591
1ab22b2a 592TSDL meta-data representation for a sequence type definition:
80fd2569 593
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594struct {
595 unsigned int length_field;
596 typedef elem_type typename[length_field];
597 typename seq_field_name;
598}
599
600A sequence can also be declared as a field type, e.g.:
80fd2569 601
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602struct {
603 unsigned int length_field;
604 long seq_field_name[length_field];
605}
80fd2569 606
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607Multiple sequences can refer to the same length field, and these length
608fields can be in a different upper dynamic scope:
609
610e.g., assuming the stream.event.header defines:
611
612stream {
613 ...
614 id = 1;
615 event.header := struct {
616 uint16_t seq_len;
617 };
618};
619
620event {
621 ...
622 stream_id = 1;
623 fields := struct {
624 long seq_a[stream.event.header.seq_len];
625 char seq_b[stream.event.header.seq_len];
626 };
627};
80fd2569 628
1ab22b2a 629The sequence elements follow the "array" specifications.
5ba9f198 630
fcba70d4 6314.2.5 Strings
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632
633Strings are an array of bytes of variable size and are terminated by a '\0'
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634"NULL" character. Their encoding is described in the TSDL meta-data. In
635absence of encoding attribute information, the default encoding is
636UTF-8.
5ba9f198 637
6672e9e1 638TSDL meta-data representation of a named string type:
80fd2569 639
359894ac 640typealias string {
5ba9f198 641 encoding = UTF8 OR ASCII;
38b8da21 642} := name;
5ba9f198 643
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644A nameless string type can be declared as a field type:
645
646string field_name; /* Use default UTF8 encoding */
5ba9f198 647
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648Strings are always aligned on byte size.
649
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6505. Event Packet Header
651
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652The event packet header consists of two parts: the "event packet header"
653is the same for all streams of a trace. The second part, the "event
654packet context", is described on a per-stream basis. Both are described
655in the TSDL meta-data. The packets are aligned on architecture-page-sized
656addresses.
3bf79539 657
6672e9e1 658Event packet header (all fields are optional, specified by TSDL meta-data):
3bf79539 659
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660- Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
661 CTF packet. This magic number is optional, but when present, it should
662 come at the very beginning of the packet.
663- Trace UUID, used to ensure the event packet match the meta-data used.
664 (note: we cannot use a meta-data checksum in every cases instead of a
665 UUID because meta-data can be appended to while tracing is active)
666 This field is optional.
667- Stream ID, used as reference to stream description in meta-data.
668 This field is optional if there is only one stream description in the
669 meta-data, but becomes required if there are more than one stream in
670 the TSDL meta-data description.
3bf79539 671
6672e9e1 672Event packet context (all fields are optional, specified by TSDL meta-data):
3bf79539 673
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674- Event packet content size (in bits).
675- Event packet size (in bits, includes padding).
cda89682 676- Event packet content checksum. Checksum excludes the event packet
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677 header.
678- Per-stream event packet sequence count (to deal with UDP packet loss). The
679 number of significant sequence counter bits should also be present, so
b11853af 680 wrap-arounds are dealt with correctly.
6672e9e1 681- Time-stamp at the beginning and time-stamp at the end of the event packet.
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682 Both timestamps are written in the packet header, but sampled respectively
683 while (or before) writing the first event and while (or after) writing the
684 last event in the packet. The inclusive range between these timestamps should
685 include all event timestamps assigned to events contained within the packet.
5ba9f198 686- Events discarded count
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687 - Snapshot of a per-stream free-running counter, counting the number of
688 events discarded that were supposed to be written in the stream prior to
689 the first event in the event packet.
5ba9f198 690 * Note: producer-consumer buffer full condition should fill the current
3bf79539 691 event packet with padding so we know exactly where events have been
5ba9f198 692 discarded.
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693- Lossless compression scheme used for the event packet content. Applied
694 directly to raw data. New types of compression can be added in following
695 versions of the format.
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696 0: no compression scheme
697 1: bzip2
698 2: gzip
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699 3: xz
700- Cypher used for the event packet content. Applied after compression.
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701 0: no encryption
702 1: AES
3bf79539 703- Checksum scheme used for the event packet content. Applied after encryption.
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704 0: no checksum
705 1: md5
706 2: sha1
707 3: crc32
708
6672e9e1 7095.1 Event Packet Header Description
3bf79539 710
fc5425db 711The event packet header layout is indicated by the trace packet.header
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712field. Here is a recommended structure type for the packet header with
713the fields typically expected (although these fields are each optional):
fc5425db 714
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715struct event_packet_header {
716 uint32_t magic;
3fde5da1 717 uint8_t uuid[16];
3bf79539 718 uint32_t stream_id;
80fd2569 719};
5ba9f198 720
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721trace {
722 ...
723 packet.header := struct event_packet_header;
724};
725
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726If the magic number is not present, tools such as "file" will have no
727mean to discover the file type.
728
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729If the uuid is not present, no validation that the meta-data actually
730corresponds to the stream is performed.
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731
732If the stream_id packet header field is missing, the trace can only
733contain a single stream. Its "id" field can be left out, and its events
734don't need to declare a "stream_id" field.
735
736
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7375.2 Event Packet Context Description
738
739Event packet context example. These are declared within the stream declaration
6672e9e1 740in the meta-data. All these fields are optional. If the packet size field is
6a7c61df 741missing, the whole stream only contains a single packet. If the content
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742size field is missing, the packet is filled (no padding). The content
743and packet sizes include all headers.
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744
745An example event packet context type:
746
80fd2569 747struct event_packet_context {
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748 uint64_t timestamp_begin;
749 uint64_t timestamp_end;
750 uint32_t checksum;
751 uint32_t stream_packet_count;
752 uint32_t events_discarded;
753 uint32_t cpu_id;
754 uint32_t/uint16_t content_size;
755 uint32_t/uint16_t packet_size;
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756 uint8_t compression_scheme;
757 uint8_t encryption_scheme;
3b0f8e4d 758 uint8_t checksum_scheme;
3bf79539 759};
5ba9f198 760
fcba70d4 761
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7626. Event Structure
763
764The overall structure of an event is:
765
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7661 - Stream Packet Context (as specified by the stream meta-data)
767 2 - Event Header (as specified by the stream meta-data)
768 3 - Stream Event Context (as specified by the stream meta-data)
769 4 - Event Context (as specified by the event meta-data)
770 5 - Event Payload (as specified by the event meta-data)
5ba9f198 771
fdf2bb05 772This structure defines an implicit dynamic scoping, where variants
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773located in inner structures (those with a higher number in the listing
774above) can refer to the fields of outer structures (with lower number in
6c7226e9 775the listing above). See Section 7.3 TSDL Scopes for more detail.
5ba9f198 776
fdf2bb05 7776.1 Event Header
fcba70d4 778
6672e9e1 779Event headers can be described within the meta-data. We hereby propose, as an
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780example, two types of events headers. Type 1 accommodates streams with less than
78131 event IDs. Type 2 accommodates streams with 31 or more event IDs.
5ba9f198 782
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783One major factor can vary between streams: the number of event IDs assigned to
784a stream. Luckily, this information tends to stay relatively constant (modulo
5ba9f198 785event registration while trace is being recorded), so we can specify different
3bf79539 786representations for streams containing few event IDs and streams containing
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787many event IDs, so we end up representing the event ID and time-stamp as
788densely as possible in each case.
5ba9f198 789
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790The header is extended in the rare occasions where the information cannot be
791represented in the ranges available in the standard event header. They are also
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792used in the rare occasions where the data required for a field could not be
793collected: the flag corresponding to the missing field within the missing_fields
794array is then set to 1.
5ba9f198 795
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796Types uintX_t represent an X-bit unsigned integer, as declared with
797either:
5ba9f198 798
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799 typealias integer { size = X; align = X; signed = false } := uintX_t;
800
801 or
802
803 typealias integer { size = X; align = 1; signed = false } := uintX_t;
5ba9f198 804
fdf2bb05 8056.1.1 Type 1 - Few event IDs
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806
807 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
808 preference).
5ba9f198 809 - Native architecture byte ordering.
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810 - For "compact" selection
811 - Fixed size: 32 bits.
812 - For "extended" selection
813 - Size depends on the architecture and variant alignment.
5ba9f198 814
80fd2569 815struct event_header_1 {
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816 /*
817 * id: range: 0 - 30.
818 * id 31 is reserved to indicate an extended header.
819 */
a9b83695 820 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
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821 variant <id> {
822 struct {
823 uint27_t timestamp;
824 } compact;
825 struct {
826 uint32_t id; /* 32-bit event IDs */
827 uint64_t timestamp; /* 64-bit timestamps */
828 } extended;
829 } v;
cb108fea 830} align(32); /* or align(8) */
5ba9f198 831
5ba9f198 832
fdf2bb05 8336.1.2 Type 2 - Many event IDs
5ba9f198 834
fcba70d4 835 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
5ba9f198 836 preference).
5ba9f198 837 - Native architecture byte ordering.
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838 - For "compact" selection
839 - Size depends on the architecture and variant alignment.
840 - For "extended" selection
841 - Size depends on the architecture and variant alignment.
5ba9f198 842
80fd2569 843struct event_header_2 {
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844 /*
845 * id: range: 0 - 65534.
846 * id 65535 is reserved to indicate an extended header.
847 */
a9b83695 848 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
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849 variant <id> {
850 struct {
851 uint32_t timestamp;
852 } compact;
853 struct {
854 uint32_t id; /* 32-bit event IDs */
855 uint64_t timestamp; /* 64-bit timestamps */
856 } extended;
857 } v;
cb108fea 858} align(16); /* or align(8) */
5ba9f198 859
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860
8616.2 Event Context
862
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863The event context contains information relative to the current event.
864The choice and meaning of this information is specified by the TSDL
865stream and event meta-data descriptions. The stream context is applied
866to all events within the stream. The stream context structure follows
867the event header. The event context is applied to specific events. Its
868structure follows the stream context structure.
5ba9f198 869
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870An example of stream-level event context is to save the event payload size with
871each event, or to save the current PID with each event. These are declared
6672e9e1 872within the stream declaration within the meta-data:
5ba9f198 873
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874 stream {
875 ...
6672e9e1 876 event.context := struct {
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877 uint pid;
878 uint16_t payload_size;
6672e9e1 879 };
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880 };
881
882An example of event-specific event context is to declare a bitmap of missing
883fields, only appended after the stream event context if the extended event
884header is selected. NR_FIELDS is the number of fields within the event (a
885numeric value).
5ba9f198 886
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887 event {
888 context = struct {
889 variant <id> {
890 struct { } compact;
891 struct {
892 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
893 } extended;
894 } v;
895 };
896 ...
897 }
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898
8996.3 Event Payload
900
901An event payload contains fields specific to a given event type. The fields
6672e9e1 902belonging to an event type are described in the event-specific meta-data
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903within a structure type.
904
9056.3.1 Padding
906
907No padding at the end of the event payload. This differs from the ISO/C standard
908for structures, but follows the CTF standard for structures. In a trace, even
909though it makes sense to align the beginning of a structure, it really makes no
910sense to add padding at the end of the structure, because structures are usually
911not followed by a structure of the same type.
912
913This trick can be done by adding a zero-length "end" field at the end of the C
914structures, and by using the offset of this field rather than using sizeof()
3bf79539 915when calculating the size of a structure (see Appendix "A. Helper macros").
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916
9176.3.2 Alignment
918
919The event payload is aligned on the largest alignment required by types
920contained within the payload. (This follows the ISO/C standard for structures)
921
922
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9237. Trace Stream Description Language (TSDL)
924
925The Trace Stream Description Language (TSDL) allows expression of the
926binary trace streams layout in a C99-like Domain Specific Language
927(DSL).
928
929
6672e9e1 9307.1 Meta-data
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MD
931
932The trace stream layout description is located in the trace meta-data.
933The meta-data is itself located in a stream identified by its name:
934"metadata".
5ba9f198 935
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936The meta-data description can be expressed in two different formats:
937text-only and packet-based. The text-only description facilitates
938generation of meta-data and provides a convenient way to enter the
939meta-data information by hand. The packet-based meta-data provides the
940CTF stream packet facilities (checksumming, compression, encryption,
941network-readiness) for meta-data stream generated and transported by a
942tracer.
943
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944The text-only meta-data file is a plain-text TSDL description. This file
945must begin with the following characters to identify the file as a CTF
9486a18c 946TSDL text-based metadata file (without the double-quotes) :
1b4d35eb 947
ec2b4db8 948"/* CTF"
1b4d35eb 949
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950It must be followed by a space, and the version of the specification
951followed by the CTF trace, e.g.:
952
953" 1.8"
954
955These characters allow automated discovery of file type and CTF
956specification version. They are interpreted as a the beginning of a
957comment by the TSDL metadata parser. The comment can be continued to
958contain extra commented characters before it is closed.
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959
960The packet-based meta-data is made of "meta-data packets", which each
961start with a meta-data packet header. The packet-based meta-data
962description is detected by reading the magic number "0x75D11D57" at the
963beginning of the file. This magic number is also used to detect the
964endianness of the architecture by trying to read the CTF magic number
965and its counterpart in reversed endianness. The events within the
966meta-data stream have no event header nor event context. Each event only
5ae2352d 967contains a "sequence" payload, which is a sequence of bits using the
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968"trace.packet.header.content_size" field as a placeholder for its length
969(the packet header size should be substracted). The formatting of this
970sequence of bits is a plain-text representation of the TSDL description.
971Each meta-data packet start with a special packet header, specific to
972the meta-data stream, which contains, exactly:
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973
974struct metadata_packet_header {
2daeaa3a 975 uint32_t magic; /* 0x75D11D57 */
3fde5da1 976 uint8_t uuid[16]; /* Unique Universal Identifier */
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977 uint32_t checksum; /* 0 if unused */
978 uint32_t content_size; /* in bits */
979 uint32_t packet_size; /* in bits */
980 uint8_t compression_scheme; /* 0 if unused */
981 uint8_t encryption_scheme; /* 0 if unused */
982 uint8_t checksum_scheme; /* 0 if unused */
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983 uint8_t major; /* CTF spec version major number */
984 uint8_t minor; /* CTF spec version minor number */
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985};
986
987The packet-based meta-data can be converted to a text-only meta-data by
988concatenating all the strings in contains.
4fafe1ad 989
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990In the textual representation of the meta-data, the text contained
991within "/*" and "*/", as well as within "//" and end of line, are
992treated as comments. Boolean values can be represented as true, TRUE,
993or 1 for true, and false, FALSE, or 0 for false. Within the string-based
994meta-data description, the trace UUID is represented as a string of
995hexadecimal digits and dashes "-". In the event packet header, the trace
996UUID is represented as an array of bytes.
fcba70d4 997
fdf2bb05 998
6c7226e9 9997.2 Declaration vs Definition
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1000
1001A declaration associates a layout to a type, without specifying where
1002this type is located in the event structure hierarchy (see Section 6).
1003This therefore includes typedef, typealias, as well as all type
1004specifiers. In certain circumstances (typedef, structure field and
1005variant field), a declaration is followed by a declarator, which specify
1006the newly defined type name (for typedef), or the field name (for
1007declarations located within structure and variants). Array and sequence,
1008declared with square brackets ("[" "]"), are part of the declarator,
a9b83695 1009similarly to C99. The enumeration base type is specified by
6c7226e9 1010": enum_base", which is part of the type specifier. The variant tag
a9b83695 1011name, specified between "<" ">", is also part of the type specifier.
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1012
1013A definition associates a type to a location in the event structure
b9606a77
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1014hierarchy (see Section 6). This association is denoted by ":=", as shown
1015in Section 7.3.
fdf2bb05
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1016
1017
6c7226e9 10187.3 TSDL Scopes
fdf2bb05 1019
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1020TSDL uses three different types of scoping: a lexical scope is used for
1021declarations and type definitions, and static and dynamic scopes are
1022used for variants references to tag fields (with relative and absolute
1023path lookups) and for sequence references to length fields.
fdf2bb05 1024
6c7226e9 10257.3.1 Lexical Scope
fdf2bb05 1026
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1027Each of "trace", "stream", "event", "struct" and "variant" have their own
1028nestable declaration scope, within which types can be declared using "typedef"
fdf2bb05 1029and "typealias". A root declaration scope also contains all declarations
7d9d7e92 1030located outside of any of the aforementioned declarations. An inner
fdf2bb05 1031declaration scope can refer to type declared within its container
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1032lexical scope prior to the inner declaration scope. Redefinition of a
1033typedef or typealias is not valid, although hiding an upper scope
fdf2bb05
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1034typedef or typealias is allowed within a sub-scope.
1035
37ab95c3 10367.3.2 Static and Dynamic Scopes
fdf2bb05 1037
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1038A local static scope consists in the scope generated by the declaration
1039of fields within a compound type. A static scope is a local static scope
1040augmented with the nested sub-static-scopes it contains.
1041
1042A dynamic scope consists in the static scope augmented with the
7d9d7e92 1043implicit event structure definition hierarchy presented at Section 6.
fdf2bb05 1044
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1045Multiple declarations of the same field name within a local static scope
1046is not valid. It is however valid to re-use the same field name in
1047different local scopes.
1048
1049Nested static and dynamic scopes form lookup paths. These are used for
1050variant tag and sequence length references. They are used at the variant
1051and sequence definition site to look up the location of the tag field
1052associated with a variant, and to lookup up the location of the length
1053field associated with a sequence.
1054
1055Variants and sequences can refer to a tag field either using a relative
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1056path or an absolute path. The relative path is relative to the scope in
1057which the variant or sequence performing the lookup is located.
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1058Relative paths are only allowed to lookup within the same static scope,
1059which includes its nested static scopes. Lookups targeting parent static
1060scopes need to be performed with an absolute path.
1061
1062Absolute path lookups use the full path including the dynamic scope
1063followed by a "." and then the static scope. Therefore, variants (or
1064sequences) in lower levels in the dynamic scope (e.g. event context) can
1065refer to a tag (or length) field located in upper levels (e.g. in the
1066event header) by specifying, in this case, the associated tag with
1067<stream.event.header.field_name>. This allows, for instance, the event
1068context to define a variant referring to the "id" field of the event
1069header as selector.
1070
284724ae 1071The dynamic scope prefixes are thus:
fdf2bb05 1072
e0d9e2c7 1073 - Trace Packet Header: <trace.packet.header. >,
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1074 - Stream Packet Context: <stream.packet.context. >,
1075 - Event Header: <stream.event.header. >,
1076 - Stream Event Context: <stream.event.context. >,
1077 - Event Context: <event.context. >,
1078 - Event Payload: <event.fields. >.
fdf2bb05 1079
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1080
1081The target dynamic scope must be specified explicitly when referring to
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1082a field outside of the static scope (absolute scope reference). No
1083conflict can occur between relative and dynamic paths, because the
1084keywords "trace", "stream", and "event" are reserved, and thus
1085not permitted as field names. It is recommended that field names
1086clashing with CTF and C99 reserved keywords use an underscore prefix to
1087eliminate the risk of generating a description containing an invalid
1088field name.
fdf2bb05 1089
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1090The information available in the dynamic scopes can be thought of as the
1091current tracing context. At trace production, information about the
1092current context is saved into the specified scope field levels. At trace
1093consumption, for each event, the current trace context is therefore
1094readable by accessing the upper dynamic scopes.
1095
fdf2bb05 1096
6c7226e9 10977.4 TSDL Examples
d285084f 1098
6672e9e1 1099The grammar representing the TSDL meta-data is presented in Appendix C.
7df6b93a 1100TSDL Grammar. This section presents a rather lighter reading that
6672e9e1 1101consists in examples of TSDL meta-data, with template values.
969f30c0 1102
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1103The stream "id" can be left out if there is only one stream in the
1104trace. The event "id" field can be left out if there is only one event
1105in a stream.
1106
5ba9f198 1107trace {
fdf2bb05 1108 major = value; /* Trace format version */
5ba9f198 1109 minor = value;
fdf2bb05 1110 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
58997e9e 1111 byte_order = be OR le; /* Endianness (required) */
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1112 packet.header := struct {
1113 uint32_t magic;
3fde5da1 1114 uint8_t uuid[16];
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1115 uint32_t stream_id;
1116 };
3bf79539 1117};
5ba9f198 1118
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1119stream {
1120 id = stream_id;
fdf2bb05 1121 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
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1122 event.header := event_header_1 OR event_header_2;
1123 event.context := struct {
77a98c82 1124 ...
3bf79539 1125 };
4fa992a5 1126 packet.context := struct {
77a98c82 1127 ...
3bf79539
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1128 };
1129};
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1130
1131event {
980015f9 1132 name = "event_name";
3bf79539 1133 id = value; /* Numeric identifier within the stream */
67f02e24 1134 stream_id = stream_id;
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1135 loglevel.identifier = "loglevel_identifier";
1136 loglevel.value = value;
4fa992a5 1137 context := struct {
fcba70d4
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1138 ...
1139 };
4fa992a5 1140 fields := struct {
80fd2569
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1141 ...
1142 };
3bf79539 1143};
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1144
1145/* More detail on types in section 4. Types */
1146
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1147/*
1148 * Named types:
1149 *
4fa992a5 1150 * Type declarations behave similarly to the C standard.
3d13ef1a
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1151 */
1152
80af8ac6 1153typedef aliased_type_specifiers new_type_declarators;
2152348f 1154
3d13ef1a 1155/* e.g.: typedef struct example new_type_name[10]; */
80fd2569 1156
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1157/*
1158 * typealias
1159 *
1160 * The "typealias" declaration can be used to give a name (including
80af8ac6
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1161 * pointer declarator specifier) to a type. It should also be used to
1162 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1163 * Typealias is a superset of "typedef": it also allows assignment of a
38b8da21 1164 * simple variable identifier to a type.
4fa992a5
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1165 */
1166
1167typealias type_class {
80fd2569 1168 ...
38b8da21 1169} := type_specifiers type_declarator;
2152348f 1170
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1171/*
1172 * e.g.:
4fa992a5 1173 * typealias integer {
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MD
1174 * size = 32;
1175 * align = 32;
1176 * signed = false;
38b8da21 1177 * } := struct page *;
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1178 *
1179 * typealias integer {
1180 * size = 32;
1181 * align = 32;
1182 * signed = true;
38b8da21 1183 * } := int;
3d13ef1a 1184 */
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1185
1186struct name {
3bf79539
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1187 ...
1188};
5ba9f198 1189
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1190variant name {
1191 ...
1192};
1193
a9b83695 1194enum name : integer_type {
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1195 ...
1196};
1197
2152348f 1198
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1199/*
1200 * Unnamed types, contained within compound type fields, typedef or typealias.
1201 */
2152348f 1202
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1203struct {
1204 ...
2152348f 1205}
5ba9f198 1206
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MD
1207struct {
1208 ...
1209} align(value)
1210
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1211variant {
1212 ...
1213}
1214
a9b83695 1215enum : integer_type {
80fd2569 1216 ...
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1217}
1218
1219typedef type new_type[length];
3bf79539 1220
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1221struct {
1222 type field_name[length];
1223}
1224
1225typedef type new_type[length_type];
1226
1227struct {
1228 type field_name[length_type];
1229}
1230
1231integer {
80fd2569 1232 ...
2152348f 1233}
3bf79539 1234
2152348f 1235floating_point {
80fd2569 1236 ...
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MD
1237}
1238
1239struct {
1240 integer_type field_name:size; /* GNU/C bitfield */
1241}
1242
1243struct {
1244 string field_name;
1245}
3bf79539 1246
fcba70d4 1247
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12488. Clocks
1249
1250Clock metadata allows to describe the clock topology of the system, as
1251well as to detail each clock parameter. In absence of clock description,
1252it is assumed that all fields named "timestamp" use the same clock
1253source, which increment once per nanosecond.
1254
1255Describing a clock and how it is used by streams is threefold: first,
1256the clock and clock topology should be described in a "clock"
1257description block, e.g.:
1258
1259enum clocks {
1260 cycle_counter,
1261};
1262
1263clock[cycle_counter] {
1264 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
1265 description = "Local CPU cycle counter";
1266 freq = 1000000000; /* frequency, in Hz */
1267 /* precision in seconds is: 1000 * (1/freq) */
1268 precision = 1000;
1269 /* clock value offset from Jan 01 1970 is: offset * (1/freq) */
1270 offset = 1326476837897235420;
1271};
1272
1273The optional field "uuid" is the unique identifier of the clock. It can
1274be used to correlate different traces that use the same clock. An
1275optional textual description string can be added with the "description"
1276field. The "freq" field is the initial frequency of the clock, in Hz. If
1277the "freq" field is not present, the frequency is assumed to be
12781000000000 (providing clock increment of 1 ns). The optional "precision"
1279field details the uncertainty on the clock measurements, in (1/freq)
1280units. The "offset" field indicates the offset from Jan 01 1970 to the
1281zero of value of the clock, in (1/freq) units. If the "offset" field is
1282not present, it is assigned the 0 value.
1283
1284Secondly, a reference to this clock should be added within an integer
1285type:
1286
1287typealias integer {
1288 size = 64; align = 1; signed = false;
1289 map = clock[cycle_counter].value;
1290} := uint64_ccnt_t;
1291
1292Thirdly, stream declarations can reference the clock they use as a
1293time-stamp source:
1294
1295struct packet_context {
1296 uint64_ccnt_t ccnt_begin;
1297 uint64_ccnt_t ccnt_end;
1298 /* ... */
1299};
1300
1301stream {
1302 /* ... */
1303 event.header := struct {
1304 uint64_ccnt_t timestamp;
1305 /* ... */
1306 }
1307 packet.context := struct packet_context;
1308};
1309
1310For a N-bit integer type referring to a clock, if the integer overflows
1311compared to the N low order bits of the clock prior value, then it is
1312assumed that one, and only one, overflow occurred. It is therefore
1313important that events encoding time on a small number of bits happen
1314frequently enough to detect when more than one N-bit overflow occurs.
1315
1316In a packet context, clock field names ending with "_begin" and "_end"
1317have a special meaning: this refers to the time-stamps at, respectively,
1318the beginning and the end of each packet.
1319
1320
3bf79539 1321A. Helper macros
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MD
1322
1323The two following macros keep track of the size of a GNU/C structure without
1324padding at the end by placing HEADER_END as the last field. A one byte end field
1325is used for C90 compatibility (C99 flexible arrays could be used here). Note
1326that this does not affect the effective structure size, which should always be
1327calculated with the header_sizeof() helper.
1328
1329#define HEADER_END char end_field
1330#define header_sizeof(type) offsetof(typeof(type), end_field)
3bf79539
MD
1331
1332
1333B. Stream Header Rationale
1334
1335An event stream is divided in contiguous event packets of variable size. These
1336subdivisions allow the trace analyzer to perform a fast binary search by time
1337within the stream (typically requiring to index only the event packet headers)
1338without reading the whole stream. These subdivisions have a variable size to
1339eliminate the need to transfer the event packet padding when partially filled
1340event packets must be sent when streaming a trace for live viewing/analysis.
1341An event packet can contain a certain amount of padding at the end. Dividing
1342streams into event packets is also useful for network streaming over UDP and
1343flight recorder mode tracing (a whole event packet can be swapped out of the
1344buffer atomically for reading).
1345
1346The stream header is repeated at the beginning of each event packet to allow
1347flexibility in terms of:
1348
1349 - streaming support,
1350 - allowing arbitrary buffers to be discarded without making the trace
1351 unreadable,
1352 - allow UDP packet loss handling by either dealing with missing event packet
1353 or asking for re-transmission.
1354 - transparently support flight recorder mode,
1355 - transparently support crash dump.
1356
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1357
1358C. TSDL Grammar
fcba70d4 1359
4fa992a5 1360/*
6c7226e9 1361 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
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1362 *
1363 * Inspired from the C99 grammar:
1364 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
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1365 * and c++1x grammar (draft)
1366 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
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MD
1367 *
1368 * Specialized for CTF needs by including only constant and declarations from
1369 * C99 (excluding function declarations), and by adding support for variants,
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1370 * sequences and CTF-specific specifiers. Enumeration container types
1371 * semantic is inspired from c++1x enum-base.
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1372 */
1373
13741) Lexical grammar
1375
13761.1) Lexical elements
1377
1378token:
1379 keyword
1380 identifier
1381 constant
1382 string-literal
1383 punctuator
1384
13851.2) Keywords
1386
1387keyword: is one of
1388
ec4404a7 1389align
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MD
1390const
1391char
2fa70eba 1392clock
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MD
1393double
1394enum
1395event
1396floating_point
1397float
1398integer
1399int
1400long
1401short
1402signed
1403stream
1404string
1405struct
1406trace
3e1e1a78 1407typealias
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MD
1408typedef
1409unsigned
1410variant
1411void
1412_Bool
1413_Complex
1414_Imaginary
1415
1416
14171.3) Identifiers
1418
1419identifier:
1420 identifier-nondigit
1421 identifier identifier-nondigit
1422 identifier digit
1423
1424identifier-nondigit:
1425 nondigit
1426 universal-character-name
1427 any other implementation-defined characters
1428
1429nondigit:
1430 _
1431 [a-zA-Z] /* regular expression */
1432
1433digit:
1434 [0-9] /* regular expression */
1435
14361.4) Universal character names
1437
1438universal-character-name:
1439 \u hex-quad
1440 \U hex-quad hex-quad
1441
1442hex-quad:
1443 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1444
14451.5) Constants
1446
1447constant:
1448 integer-constant
1449 enumeration-constant
1450 character-constant
1451
1452integer-constant:
1453 decimal-constant integer-suffix-opt
1454 octal-constant integer-suffix-opt
1455 hexadecimal-constant integer-suffix-opt
1456
1457decimal-constant:
1458 nonzero-digit
1459 decimal-constant digit
1460
1461octal-constant:
1462 0
1463 octal-constant octal-digit
1464
1465hexadecimal-constant:
1466 hexadecimal-prefix hexadecimal-digit
1467 hexadecimal-constant hexadecimal-digit
1468
1469hexadecimal-prefix:
1470 0x
1471 0X
1472
1473nonzero-digit:
1474 [1-9]
1475
1476integer-suffix:
1477 unsigned-suffix long-suffix-opt
1478 unsigned-suffix long-long-suffix
1479 long-suffix unsigned-suffix-opt
1480 long-long-suffix unsigned-suffix-opt
1481
1482unsigned-suffix:
1483 u
1484 U
1485
1486long-suffix:
1487 l
1488 L
1489
1490long-long-suffix:
1491 ll
1492 LL
1493
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MD
1494enumeration-constant:
1495 identifier
1496 string-literal
1497
1498character-constant:
1499 ' c-char-sequence '
1500 L' c-char-sequence '
1501
1502c-char-sequence:
1503 c-char
1504 c-char-sequence c-char
1505
1506c-char:
1507 any member of source charset except single-quote ('), backslash
1508 (\), or new-line character.
1509 escape-sequence
1510
1511escape-sequence:
1512 simple-escape-sequence
1513 octal-escape-sequence
1514 hexadecimal-escape-sequence
1515 universal-character-name
1516
1517simple-escape-sequence: one of
1518 \' \" \? \\ \a \b \f \n \r \t \v
1519
1520octal-escape-sequence:
1521 \ octal-digit
1522 \ octal-digit octal-digit
1523 \ octal-digit octal-digit octal-digit
1524
1525hexadecimal-escape-sequence:
1526 \x hexadecimal-digit
1527 hexadecimal-escape-sequence hexadecimal-digit
1528
15291.6) String literals
1530
1531string-literal:
1532 " s-char-sequence-opt "
1533 L" s-char-sequence-opt "
1534
1535s-char-sequence:
1536 s-char
1537 s-char-sequence s-char
1538
1539s-char:
1540 any member of source charset except double-quote ("), backslash
1541 (\), or new-line character.
1542 escape-sequence
1543
15441.7) Punctuators
1545
1546punctuator: one of
1547 [ ] ( ) { } . -> * + - < > : ; ... = ,
1548
1549
15502) Phrase structure grammar
1551
1552primary-expression:
1553 identifier
1554 constant
1555 string-literal
1556 ( unary-expression )
1557
1558postfix-expression:
1559 primary-expression
1560 postfix-expression [ unary-expression ]
1561 postfix-expression . identifier
1562 postfix-expressoin -> identifier
1563
1564unary-expression:
1565 postfix-expression
1566 unary-operator postfix-expression
1567
1568unary-operator: one of
1569 + -
1570
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MD
1571assignment-operator:
1572 =
1573
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1574type-assignment-operator:
1575 :=
1576
4fa992a5 1577constant-expression-range:
73d61ac3 1578 unary-expression ... unary-expression
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MD
1579
15802.2) Declarations:
1581
1582declaration:
689e04b4 1583 declaration-specifiers declarator-list-opt ;
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MD
1584 ctf-specifier ;
1585
1586declaration-specifiers:
689e04b4 1587 storage-class-specifier declaration-specifiers-opt
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MD
1588 type-specifier declaration-specifiers-opt
1589 type-qualifier declaration-specifiers-opt
1590
1591declarator-list:
1592 declarator
1593 declarator-list , declarator
1594
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1595abstract-declarator-list:
1596 abstract-declarator
1597 abstract-declarator-list , abstract-declarator
1598
4fa992a5
MD
1599storage-class-specifier:
1600 typedef
1601
1602type-specifier:
1603 void
1604 char
1605 short
1606 int
1607 long
1608 float
1609 double
1610 signed
1611 unsigned
1612 _Bool
1613 _Complex
cfdd51ec 1614 _Imaginary
9dfcfc0f
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1615 struct-specifier
1616 variant-specifier
4fa992a5
MD
1617 enum-specifier
1618 typedef-name
1619 ctf-type-specifier
1620
ec4404a7 1621align-attribute:
73d61ac3 1622 align ( unary-expression )
ec4404a7 1623
4fa992a5 1624struct-specifier:
ec4404a7
MD
1625 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1626 struct identifier align-attribute-opt
4fa992a5
MD
1627
1628struct-or-variant-declaration-list:
1629 struct-or-variant-declaration
1630 struct-or-variant-declaration-list struct-or-variant-declaration
1631
1632struct-or-variant-declaration:
1633 specifier-qualifier-list struct-or-variant-declarator-list ;
eacb16d1 1634 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
6143bab7
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1635 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1636 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
4fa992a5
MD
1637
1638specifier-qualifier-list:
1639 type-specifier specifier-qualifier-list-opt
1640 type-qualifier specifier-qualifier-list-opt
1641
1642struct-or-variant-declarator-list:
1643 struct-or-variant-declarator
1644 struct-or-variant-declarator-list , struct-or-variant-declarator
1645
1646struct-or-variant-declarator:
1647 declarator
73d61ac3 1648 declarator-opt : unary-expression
4fa992a5
MD
1649
1650variant-specifier:
1651 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1652 variant identifier variant-tag
1653
1654variant-tag:
37ab95c3 1655 < unary-expression >
4fa992a5
MD
1656
1657enum-specifier:
1658 enum identifier-opt { enumerator-list }
1659 enum identifier-opt { enumerator-list , }
1660 enum identifier
a9b83695
MD
1661 enum identifier-opt : declaration-specifiers { enumerator-list }
1662 enum identifier-opt : declaration-specifiers { enumerator-list , }
4fa992a5
MD
1663
1664enumerator-list:
1665 enumerator
1666 enumerator-list , enumerator
1667
1668enumerator:
1669 enumeration-constant
8d2d41f7
MD
1670 enumeration-constant assignment-operator unary-expression
1671 enumeration-constant assignment-operator constant-expression-range
4fa992a5
MD
1672
1673type-qualifier:
1674 const
1675
1676declarator:
1677 pointer-opt direct-declarator
1678
1679direct-declarator:
1680 identifier
1681 ( declarator )
1ab22b2a 1682 direct-declarator [ unary-expression ]
4fa992a5 1683
d285084f
MD
1684abstract-declarator:
1685 pointer-opt direct-abstract-declarator
1686
1687direct-abstract-declarator:
1688 identifier-opt
1689 ( abstract-declarator )
1ab22b2a 1690 direct-abstract-declarator [ unary-expression ]
d285084f
MD
1691 direct-abstract-declarator [ ]
1692
4fa992a5 1693pointer:
3b0f8e4d
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1694 * type-qualifier-list-opt
1695 * type-qualifier-list-opt pointer
4fa992a5
MD
1696
1697type-qualifier-list:
1698 type-qualifier
1699 type-qualifier-list type-qualifier
1700
4fa992a5
MD
1701typedef-name:
1702 identifier
1703
17042.3) CTF-specific declarations
1705
1706ctf-specifier:
1707 event { ctf-assignment-expression-list-opt }
1708 stream { ctf-assignment-expression-list-opt }
1709 trace { ctf-assignment-expression-list-opt }
b12919a5
MD
1710 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1711 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
4fa992a5
MD
1712
1713ctf-type-specifier:
1714 floating_point { ctf-assignment-expression-list-opt }
1715 integer { ctf-assignment-expression-list-opt }
1716 string { ctf-assignment-expression-list-opt }
7609d3c7 1717 string
4fa992a5
MD
1718
1719ctf-assignment-expression-list:
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1720 ctf-assignment-expression ;
1721 ctf-assignment-expression-list ctf-assignment-expression ;
4fa992a5
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1722
1723ctf-assignment-expression:
1724 unary-expression assignment-operator unary-expression
1725 unary-expression type-assignment-operator type-specifier
eacb16d1 1726 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
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1727 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1728 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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