README.md
1zcbor
2=====
3
4zcbor is a low footprint [CBOR](https://en.wikipedia.org/wiki/CBOR) library in the C language (C++ compatible), tailored for use in microcontrollers.
5It comes with a schema-driven script tool that can validate your data, or even generate code.
6The schema language (CDDL) allows creating very advanced and detailed schemas.
7
8The validation and conversion part of the tool works with YAML and JSON data, in addition to CBOR.
9It can for example validate a YAML file against a schema and convert it into CBOR.
10
11The code generation part of the tool generates C code based on the given schema.
12The generated code performs CBOR encoding and decoding using the C library, while also validating the data against all the rules in the schema.
13
14The schema language used by zcbor is CDDL (Consise Data Definition Language) which is a powerful human-readable data description language defined in [IETF RFC 8610](https://datatracker.ietf.org/doc/rfc8610/).
15
16
17Features
18========
19
20Here are some possible ways zcbor can be used:
21
22 - C code:
23 - As a low-footprint CBOR decoding/encoding library similar to TinyCBOR/QCBOR/NanoCBOR. The library can be used independently of the Python script. ([More information](#cbor-decodingencoding-library))
24 - To generate C code (using the Python script) for validating and decoding or encoding CBOR, for use in optimized or constrained environments, such as microcontrollers. ([More information](#code-generation))
25 - Python script and module ([More information](#python-script-and-module)):
26 - Validate a YAML/JSON file and translate it into CBOR e.g. for transmission.
27 - Validate a YAML/JSON/CBOR file before processing it with some other tool
28 - Decode and validate incoming CBOR data into human-readable YAML/JSON.
29 - As part of a python script that processes YAML/JSON/CBOR files.
30 - Uses the same internal representation used by the PyYAML/json/cbor2 libraries.
31 - Do validation against a CDDL schema.
32 - Create a read-only representation via named tuples (with names taken from the CDDL schema).
33
34
35Getting started
36===============
37
38There are samples in the [samples](samples) directory that demonstrate different ways to use zcbor, both the script tool and the C code.
39
401. The [hello_world sample](samples/hello_world/README.md) is a minimum examples of encoding and decoding using the C library.
412. The [pet sample](samples/pet/README.md) shows a how to use the C library together with generated code, and how to use the script tool to do code generation and data conversion.
42
43The [tests](tests) also demonstrate how to use zcbor in different ways. The [encoding](tests/encode), [decoding](tests/decode), and [unit](tests/unit) tests run using [Zephyr](https://github.com/zephyrproject-rtos/zephyr) (the samples do not use Zephyr).
44
45Should I use code generation or the library directly?
46-----------------------------------------------------
47
48The benefit of using code generation is greater for decoding than encoding.
49This is because decoding is generally more complex than encoding, since when decoding you have to gracefully handle all possible payloads.
50The code generation will provide a number of checks that are tedious to write manually.
51These checks ensure that the payload is well-formed.
52
53
54CBOR decoding/encoding library
55==============================
56
57The CBOR library can be found in [include/](include) and [src/](src) and can be used directly, by including the files in your project.
58If using zcbor with Zephyr, the library will be available when the [CONFIG_ZCBOR](https://docs.zephyrproject.org/latest/kconfig.html#CONFIG_ZCBOR) config is enabled.
59
60The library is also used by generated code. See the the [Code generation](#code-generation) section for more info about code generation.
61
62The C library is C++ compatible.
63
64The zcbor state object
65----------------------
66
67To do encoding or decoding with the library, instantiate a `zcbor_state_t` object, which is most easily done using the `ZCBOR_STATE_*()` macros, look below or in the [hello_world](samples/hello_world/src/main.c) sample for example code.
68
69The `elem_count` member refers to the number of encoded objects in the current list or map.
70`elem_count` starts again when entering a nested list or map, and is restored when exiting.
71
72`elem_count` is one reason for needing "backup" states (the other is to allow rollback of the payload).
73Backups are needed for _decoding_ if there are any lists, maps, or CBOR-encoded strings (`zcbor_bstr_*_decode`) in the data.
74Backups are needed for _encoding_ if there are any lists or maps *and* you are using canonical encoding (`ZCBOR_CANONICAL`), or when using the `zcbor_bstr_*_encode` functions.
75
76```c
77/** Initialize a decoding state (could include an array of backup states).
78 * After calling this, decode_state[0] is ready to be used with the decoding APIs. */
79ZCBOR_STATE_D(decode_state, n, payload, payload_len, elem_count);
80
81/** Initialize an encoding state (could include an array of backup states).
82 * After calling this, encode_state[0] is ready to be used with the encoding APIs. */
83ZCBOR_STATE_E(encode_state, n, payload, payload_len, 0);
84```
85
86Configuration
87-------------
88
89The C library has a few compile-time configuration options.
90These configuration options can be enabled by adding them as compile definitions to the build.
91If using zcbor with Zephyr, use the [Kconfig options](https://github.com/zephyrproject-rtos/zephyr/blob/main/modules/zcbor/Kconfig) instead.
92
93Name | Description
94------------------------- | -----------
95`ZCBOR_CANONICAL` | When encoding lists and maps, do not use indefinite length encoding. Enabling `ZCBOR_CANONICAL` increases code size and makes the encoding library more often use state backups.
96`ZCBOR_VERBOSE` | Print messages on encoding/decoding errors (`zcbor_print()`), and also a trace message (`zcbor_trace()`) for each decoded value, and in each generated function (when using code generation). Requires `printk` as found in Zephyr.
97`ZCBOR_ASSERTS` | Enable asserts (`zcbor_assert()`). When they fail, the assert statements instruct the current function to return a `ZCBOR_ERR_ASSERTION` error. If `ZCBOR_VERBOSE` is enabled, a message is printed.
98`ZCBOR_STOP_ON_ERROR` | Enable the `stop_on_error` functionality. This makes all functions abort their execution if called when an error has already happened.
99`ZCBOR_BIG_ENDIAN` | All decoded values are returned as big-endian. The default is little-endian.
100
101
102Python script and module
103========================
104
105The zcbor.py script can directly read CBOR, YAML, or JSON data and validate it against a CDDL description.
106It can also freely convert the data between CBOR/YAML/JSON.
107It can also output the data to a C file formatted as a byte array.
108
109Invoking zcbor.py from the command line
110---------------------------------------
111
112zcbor.py can be installed via [`pip`](https://pypi.org/project/zcbor/), or alternatively invoked directly from its location in this repo.
113
114Following are some generalized examples for validating, and for converting (which also validates) data from the command line.
115The script infers the data format from the file extension, but the format can also be specified explicitly.
116See `zcbor validate --help` and `zcbor convert --help` for more information.
117
118```sh
119zcbor validate -c <CDDL description file> -t <which CDDL type to expect> -i <input data file>
120zcbor convert -c <CDDL description file> -t <which CDDL type to expect> -i <input data file> -o <output data file>
121```
122
123Or directly from within the repo.
124
125```sh
126python3 <zcbor base>/zcbor/zcbor.py validate -c <CDDL description file> -t <which CDDL type to expect> -i <input data file>
127python3 <zcbor base>/zcbor/zcbor.py convert -c <CDDL description file> -t <which CDDL type to expect> -i <input data file> -o <output data file>
128```
129
130You can see an example of the conversions in [tests/cases/yaml_compatibility.yaml](tests/cases/yaml_compatibility.yaml) and its CDDL file [tests/cases/yaml_compatibility.cddl](tests/cases/yaml_compatibility.cddl).
131
132Importing zcbor in a Python script
133----------------------------------
134
135Importing zcbor gives access to the DataTranslator class which is used to implement the command line conversion features.
136DataTranslator can be used to programmatically perform the translations, or to manipulate the data.
137When accessing the data, you can choose between two internal formats:
138
139 1. The format provided by the [cbor2](https://pypi.org/project/cbor2/), [yaml (PyYAML)](https://pypi.org/project/PyYAML/), and [json](https://docs.python.org/3/library/json.html) packages.
140 This is a format where the serialization types (map, list, string, number etc.) are mapped directly to the corresponding Python types.
141 This format is common between these packages, which makes translation very simple.
142 When returning this format, DataTranslator hides the idiomatic representations for bytestrings, tags, and non-text keys described above.
143 2. A custom format which allows accessing the data via the names from the CDDL description file.
144 This format is implemented using named tuples, and is immutable, meaning that it can be used for inspecting data, but not for changing or creating data.
145
146Making CBOR YAML-/JSON-compatible
147---------------------------------
148
149Since CBOR supports more data types than YAML and JSON, zcbor can optionally use a bespoke format when converting to/from YAML/JSON.
150This is controlled with the `--yaml-compatibility` option to `convert` and `validate`.
151This is relevant when handling YAML/JSON conversions of data that uses the unsupported features.
152The following data types are supported by CBOR, but not by YAML (or JSON which is a subset of YAML):
153
154 1. bytestrings: YAML supports only text strings. In YAML, bytestrings are represented as `{"zcbor_bstr": "<hex-formatted bytestring>"}`, or as `{"zcbor_bstr": <any type>}` if the CBOR bytestring contains CBOR-formatted data, in which the data is decoded into `<any type>`.
155 2. map keys other than text string: In YAML, such key value pairs are represented as `{"zcbor_keyval<unique int>": {"key": <key, not text>, "val": <value>}}`.
156 3. tags: In cbor2, tags are represented by a special type, `cbor2.CBORTag`. In YAML, these are represented as `{"zcbor_tag": <tag number>, "zcbor_tag_val": <tagged data>}`.
157 4. undefined: In cbor2, undefined has its own value `cbor2.types.undefined`. In YAML, undefined is represented as: `["zcbor_undefined"]`.
158
159You can see an example of the conversions in [tests/cases/yaml_compatibility.yaml](tests/cases/yaml_compatibility.yaml) and its CDDL file [tests/cases/yaml_compatibility.cddl](tests/cases/yaml_compatibility.cddl).
160
161
162Code generation
163===============
164
165Code generation is invoked with the `zcbor code` command:
166
167```sh
168zcbor code <--decode or --encode or both> -c <CDDL description file(s)> -t <which CDDL type(s) to expose in the API> --output-cmake <path to place the generated CMake file at>
169zcbor code <--decode or --encode or both> -c <CDDL description file(s)> -t <which CDDL type(s) to expose in the API> --oc <path to the generated C file> --oh <path to the generated header file> --oht <path to the generated types header>
170```
171
172When you call this, zcbor reads the CDDL files and creates C struct types to match the types described in the CDDL.
173It then creates code that uses the C library to decode CBOR data into the structs, and/or encode CBOR from the data in the structs.
174Finally, it takes the "entry types" (`-t`) and creates a public API function for each of them.
175While doing these things, it will make a number of optimizations, e.g. inlining code for small types and removing ununsed functions.
176It outputs the generated code into header and source files and optionally creates a CMake file to build them.
177
178The `zcbor code` command reads one or more CDDL file(s) and generates some or all of these files:
179 - A header file with types (always)
180 - A header file with declarations for decoding functions (if `--decode`/`-d` is specified)
181 - A C file with decoding functions (if `--decode`/`-d` is specified)
182 - A header file with declarations for encoding functions (if `--encode`/`-e` is specified)
183 - A C file with encoding functions (if `--encode`/`-e` is specified)
184 - A CMake file that creates a library with the generated code and the C library (if `--output-cmake` is specified).
185
186CDDL allows placing restrictions on the members of your data.
187Restrictions can be on type (int/string/list/bool etc.), on content (e.g. values/sizes of ints or strings), and repetition (e.g. the number of members in a list).
188The generated code will validate the input, which means that it will check all the restriction set in the CDDL description, and fail if a restriction is broken.
189
190There are tests for the code generation in [tests/decode](tests/decode) and [tests/encode](tests/encode).
191The tests require [Zephyr](https://github.com/zephyrproject-rtos/zephyr) (if your system is set up to build Zephyr samples, the tests should also build).
192
193The generated C code is C++ compatible.
194
195Build system
196------------
197
198When calling zcbor with the argument `--output-cmake <file path>`, a CMake file will be created at that location.
199The generated CMake file creates a target library and adds the generated and non-generated source files as well as required include directories to it.
200This CMake file can then be included in your project's `CMakeLists.txt` file, and the target can be linked into your project.
201This is demonstrated in the tests, e.g. at [tests/decode/test3_simple/CMakeLists.txt](tests/decode/test3_simple/CMakeLists.txt).
202zcbor can be instructed to copy the non-generated sources to the same location as the generated sources with `--copy-sources`.
203
204
205Usage Example
206=============
207
208There are buildable examples in the [samples](samples) directory.
209
210To see how to use the C library directly, see the (hello_world)[samples/hello_world/src/main.c] sample, or the (pet)[samples/pet/src/main.c] sample (look for calls to functions prefixed with `zcbor_`).
211
212To see how to use code generation, see the (pet)[samples/pet/src/main.c] sample.
213
214Look at the (CMakeLists.txt)[samples/pet/CMakeLists.txt] file to see how zcbor is invoked for code generation (and for conversion).
215
216To see how to do conversion, see the (pet)[samples/pet/CMakeLists.txt] sample.
217
218Below are some additional examples of how to invoke zcbor for code generation and for converting/validating
219
220Code generation
221---------------
222
223```sh
224python3 <zcbor base>/zcbor/zcbor.py code -c pet.cddl -d -t Pet --oc pet_decode.c --oh pet_decode.h
225# or
226zcbor code -c pet.cddl -d -t Pet --oc pet_decode.c --oh pet_decode.h
227```
228
229Converting
230----------
231
232Here is an example call for converting from YAML to CBOR:
233
234```sh
235python3 <zcbor base>/zcbor/zcbor.py convert -c pet.cddl -t Pet -i mypet.yaml -o mypet.cbor
236# or
237zcbor convert -c pet.cddl -t Pet -i mypet.yaml -o mypet.cbor
238```
239
240Which takes a yaml structure from mypet.yaml, validates it against the Pet type in the CDDL description in pet.cddl, and writes binary CBOR data to mypet.cbor.
241
242Validating
243----------
244
245Here is an example call for validating a JSON file:
246
247```sh
248python3 <zcbor base>/zcbor/zcbor.py validate -c pet.cddl -t Pet --yaml-compatibility -i mypet.json
249# or
250zcbor validate -c pet.cddl -t Pet --yaml-compatibility -i mypet.json
251```
252
253Which takes the json structure in mypet.json, converts any [yaml-compatible](#making-cbor-yaml-json-compatible) values to their original form, and validates that against the Pet type in the CDDL description in pet.cddl.
254
255
256Running tests
257=============
258
259The tests for the generated code are based on the Zephyr ztest library.
260These tests can be found in [tests/decode](tests/decode) and [tests/encode](tests/encode).
261To set up the environment to run the ztest tests, follow [Zephyr's Getting Started Guide](https://docs.zephyrproject.org/latest/getting_started/index.html), or see the workflow in the [`.github`](.github) directory.
262
263Tests for `convert` and `verify` are implemented with the unittest module.
264These tests can be found in [tests/scripts/test_zcbor.py](tests/scripts/test_zcbor.py).
265In this file there are also tests for code style of all python scripts, using the `pycodestyle` library.
266
267Tests for the docs, samples, etc. can be found in [tests/scripts/test_repo_files.py](tests/scripts/test_repo_files.py).
268
269For running the tests locally, there is [`tests/test.sh`](tests/test.sh) which runs all above tests.
270
271
272Introduction to CDDL
273====================
274
275In CDDL you define types from other types.
276Types can be defined from base types, or from other types you define.
277Types are declared with '`=`', e.g. `Foo = int` which declares the type `Foo` to be an integer, analogous to `typedef int Foo;` in C.
278CDDL defines the following base types (this is not an exhaustive list):
279
280 - `int`: Positive or negative integer
281 - `uint`: Positive integer
282 - `bstr`: Byte string
283 - `tstr`: Text string
284 - `bool`: Boolean
285 - `nil`: Nil/Null value
286 - `float`: Floating point value
287 - `any`: Any single element
288
289CDDL allows creating aggregate types:
290
291 - `[]`: List. Elements don't need to have the same type.
292 - `{}`: Map. Key/value pairs as are declared as `<key> => <value>` or `<key>: <value>`. Note that `:` is also used for labels.
293 - `()`: Groups. Grouping with no enclosing type, which means that e.g. `Foo = [(int, bstr)]` is equivalent to `Foo = [int, bstr]`.
294 - `/`: Unions. Analogous to unions in C. E.g. `Foo = int/bstr/Bar` where Foo is either an int, a bstr, or Bar (some custom type).
295
296Literals can be used instead of the base type names:
297
298 - Number: `Foo = 3`, where Foo is a uint with the additional requirement that it must have the value 3.
299 - Number range: `Foo = -100..100`, where Foo is an int with value between -100 and 100.
300 - Text string: `Foo = "hello"`, where Foo is a tstr with the requirement that it must be "hello".
301 - True/False: `Foo = false`, where Foo is a bool which is always false.
302
303Base types can also be restricted in other ways:
304
305 - `.size`: Works for integers and strings. E.g. `Foo = uint .size 4` where Foo is a uint exactly 4 bytes long.
306 - `.cbor`/`.cborseq`: E.g. `Foo = bstr .cbor Bar` where Foo is a bstr whose contents must be CBOR data decodeable as the Bar type.
307
308An element can be repeated:
309
310 - `?`: 0 or 1 time. E.g. `Foo = [int, ?bstr]`, where Foo is a list with an int possibly followed by a bstr.
311 - `*`: 0 or more times. E.g. `Foo = [*tstr]`, where Foo is a list containing 0 or more tstrs.
312 - `+`: 1 or more times. E.g. `Foo = [+Bar]`.
313 - `x*y`: Between x and y times, inclusive. E.g. `Foo = {4*8(int => bstr)}` where Foo is a map with 4 to 8 key/value pairs where each key is an int and each value is a bstr.
314
315Note that in the zcbor script and its generated code, the number of entries supported via `*` and `+` is affected by the default_max_qty value.
316
317Any element can be labeled with `:`.
318The label is only for readability and does not impact the data structure in any way.
319E.g. `Foo = [name: tstr, age: uint]` is equivalent to `Foo = [tstr, uint]`.
320
321See [pet.cddl](tests/cases/pet.cddl) for CDDL example code.
322
323
324Introduction to CBOR
325====================
326
327CBOR's format is described well on [Wikipedia](https://en.wikipedia.org/wiki/CBOR), but here's a synopsis:
328
329Encoded CBOR data elements look like this.
330
331```
332| Header | Value | Payload |
333| 1 byte | 0, 1, 2, 4, or 8 bytes | 0 - 2^64-1 bytes/elements |
334| 3 bits | 5 bits |
335| Major Type | Additional Info |
336```
337
338The available major types can be seen in `zcbor_major_type_t`.
339
340For all major types, Values 0-23 are encoded directly in the _Additional info_, meaning that the _Value_ field is 0 bytes long.
341If _Additional info_ is 24, 25, 26, or 27, the _Value_ field is 1, 2, 4, or 8 bytes long, respectively.
342
343Major types `pint` (0), `nint` (1), `tag` (6), and `simple` (7) elements have no payload, only _Value_.
344
345 * `pint`: Interpret the _Value_ as a positive integer.
346 * `nint`: Interpret the _Value_ as a positive integer, then multiply by -1 and subtract 1.
347 * `tag`: The _Value_ says something about the next non-tag element.
348 See the [CBOR tag documentation](https://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml) for details.
349 * `simple`: Different _Additional info_ mean different things:
350 * 0-19: Unassigned simple values.
351 * 20: `false` simple value
352 * 21: `true` simple value
353 * 22: `null` simple value
354 * 23: `undefined` simple value
355 * 24: Interpret the _Value_ as a 1 byte simple value. These simple values are currently unassigned.
356 * 25: Interpret the _Value_ as an IEEE 754 float16.
357 * 26: Interpret the _Value_ as an IEEE 754 float32.
358 * 27: Interpret the _Value_ as an IEEE 754 float64.
359 * 31: End of an indefinite-length `list` or `map`.
360
361For `bstr` (2), `tstr` (3), `list` (4), and `map` (5), the _Value_ describes the length of the _Payload_.
362For `bstr` and `tstr`, the length is in bytes, for `list`, the length is in number of elements, and for `map`, the length is in number of key/value element pairs.
363
364For `list` and `map`, sub elements are regular CBOR elements with their own _Header_, _Value_ and _Payload_. `list`s and `map`s can be recursively encoded.
365If a `list` or `map` has _Additional info_ 31, it is "indefinite-length", which means it has an "unknown" number of elements.
366Instead, its end is marked by a `simple` with _Additional info_ 31 (byte value 0xFF).
367
368
369History
370=======
371
372zcbor (then "cddl-gen") was initially conceived as a code generation project.
373It was inspired by the need to securely decode the complex manifest data structures in the [IETF SUIT specification](https://datatracker.ietf.org/doc/draft-ietf-suit-manifest/).
374This is reflected in the fact that there are multiple zcbor tests that use the CDDL and examples from various revisions of that specification.
375Decoding/deserializing data securely requires doing some quite repetitive checks on each data element, to be sure that you are not decoding gibberish.
376This is where code generation could pull a lot of weight.
377Later it was discovered that the CBOR library that was designed to used by generated code could be useful by itself.
378The script was also expanded so it could directly manipulate CBOR data.
379Since CBOR, YAML, and JSON are all represented in roughly the same way internally in Python, it was easy to expand that data manipulation to support YAML and JSON.
380
381Some places where zcbor is currently used:
382- [MCUboot's serial recovery mechanism](https://github.com/mcu-tools/mcuboot/blob/main/boot/boot_serial/src/boot_serial.c)
383- [Zephyr's mcumgr](https://github.com/zephyrproject-rtos/zephyr/blob/main/subsys/mgmt/mcumgr/grp/img_mgmt/src/img_mgmt.c)
384- [Zephyr's LwM2M SenML](https://github.com/zephyrproject-rtos/zephyr/blob/main/subsys/net/lib/lwm2m/lwm2m_rw_senml_cbor.c)
385- [nRF Connect SDK's full modem update mechanism](https://github.com/nrfconnect/sdk-nrf/blob/main/subsys/mgmt/fmfu/src/fmfu_mgmt.c)
386- [nRF Connect SDK's nrf_rpc](https://github.com/nrfconnect/sdk-nrfxlib/blob/main/nrf_rpc/nrf_rpc_cbor.c)
387
388
389Command line documentation
390==========================
391
392Added via `add_helptext.py`
393
394zcbor --help
395------------
396
397```
398usage: zcbor [-h] [--version] {code,validate,convert} ...
399
400Parse a CDDL file and validate/convert between YAML, JSON, and CBOR. Can also
401generate C code for validation/encoding/decoding of CBOR.
402
403positional arguments:
404 {code,validate,convert}
405
406options:
407 -h, --help show this help message and exit
408 --version show program's version number and exit
409
410```
411
412zcbor code --help
413-----------------
414
415```
416usage: zcbor code [-h] -c CDDL [--no-prelude] [-v]
417 [--default-max-qty DEFAULT_MAX_QTY] [--output-c OUTPUT_C]
418 [--output-h OUTPUT_H] [--output-h-types OUTPUT_H_TYPES]
419 [--copy-sources] [--output-cmake OUTPUT_CMAKE] -t
420 ENTRY_TYPES [ENTRY_TYPES ...] [-d] [-e] [--time-header]
421 [--git-sha-header] [-b {32,64}]
422 [--include-prefix INCLUDE_PREFIX] [-s]
423 [--file-header FILE_HEADER]
424
425Parse a CDDL file and produce C code that validates and xcodes CBOR.
426The output from this script is a C file and a header file. The header file
427contains typedefs for all the types specified in the cddl input file, as well
428as declarations to xcode functions for the types designated as entry types when
429running the script. The c file contains all the code for decoding and validating
430the types in the CDDL input file. All types are validated as they are xcoded.
431
432Where a `bstr .cbor <Type>` is specified in the CDDL, AND the Type is an entry
433type, the xcoder will not xcode the string, only provide a pointer into the
434payload buffer. This is useful to reduce the size of typedefs, or to break up
435decoding. Using this mechanism is necessary when the CDDL contains self-
436referencing types, since the C type cannot be self referencing.
437
438This script requires 'regex' for lookaround functionality not present in 're'.
439
440options:
441 -h, --help show this help message and exit
442 -c CDDL, --cddl CDDL Path to one or more input CDDL file(s). Passing
443 multiple files is equivalent to concatenating them.
444 --no-prelude Exclude the standard CDDL prelude from the build. The
445 prelude can be viewed at zcbor/cddl/prelude.cddl in
446 the repo, or together with the script.
447 -v, --verbose Print more information while parsing CDDL and
448 generating code.
449 --default-max-qty DEFAULT_MAX_QTY, --dq DEFAULT_MAX_QTY
450 Default maximum number of repetitions when no maximum
451 is specified. This is needed to construct complete C
452 types. The default_max_qty can usually be set to a
453 text symbol if desired, to allow it to be configurable
454 when building the code. This is not always possible,
455 as sometimes the value is needed for internal
456 computations. If so, the script will raise an
457 exception.
458 --output-c OUTPUT_C, --oc OUTPUT_C
459 Path to output C file. If both --decode and --encode
460 are specified, _decode and _encode will be appended to
461 the filename when creating the two files. If not
462 specified, the path and name will be based on the
463 --output-cmake file. A 'src' directory will be created
464 next to the cmake file, and the C file will be placed
465 there with the same name (except the file extension)
466 as the cmake file.
467 --output-h OUTPUT_H, --oh OUTPUT_H
468 Path to output header file. If both --decode and
469 --encode are specified, _decode and _encode will be
470 appended to the filename when creating the two files.
471 If not specified, the path and name will be based on
472 the --output-cmake file. An 'include' directory will
473 be created next to the cmake file, and the C file will
474 be placed there with the same name (except the file
475 extension) as the cmake file.
476 --output-h-types OUTPUT_H_TYPES, --oht OUTPUT_H_TYPES
477 Path to output header file with typedefs (shared
478 between decode and encode). If not specified, the path
479 and name will be taken from the output header file
480 (--output-h), with '_types' added to the file name.
481 --copy-sources Copy the non-generated source files (zcbor_*.c/h) into
482 the same directories as the generated files.
483 --output-cmake OUTPUT_CMAKE
484 Path to output CMake file. The filename of the CMake
485 file without '.cmake' is used as the name of the CMake
486 target in the file. The CMake file defines a CMake
487 target with the zcbor source files and the generated
488 file as sources, and the zcbor header files' and
489 generated header files' folders as
490 include_directories. Add it to your project via
491 include() in your CMakeLists.txt file, and link the
492 target to your program. This option works with or
493 without the --copy-sources option.
494 -t ENTRY_TYPES [ENTRY_TYPES ...], --entry-types ENTRY_TYPES [ENTRY_TYPES ...]
495 Names of the types which should have their xcode
496 functions exposed.
497 -d, --decode Generate decoding code. Either --decode or --encode or
498 both must be specified.
499 -e, --encode Generate encoding code. Either --decode or --encode or
500 both must be specified.
501 --time-header Put the current time in a comment in the generated
502 files.
503 --git-sha-header Put the current git sha of zcbor in a comment in the
504 generated files.
505 -b {32,64}, --default-bit-size {32,64}
506 Default bit size of integers in code. When integers
507 have no explicit bounds, assume they have this bit
508 width. Should follow the bit width of the architecture
509 the code will be running on.
510 --include-prefix INCLUDE_PREFIX
511 When #include'ing generated files, add this path
512 prefix to the filename.
513 -s, --short-names Attempt to make most generated struct member names
514 shorter. This might make some names identical which
515 will cause a compile error. If so, tweak the CDDL
516 labels or layout, or disable this option. This might
517 also make enum names different from the corresponding
518 union members.
519 --file-header FILE_HEADER
520 Header to be included in the comment at the top of
521 generated C files, e.g. copyright.
522
523```
524
525zcbor validate --help
526---------------------
527
528```
529usage: zcbor validate [-h] -c CDDL [--no-prelude] [-v] -i INPUT
530 [--input-as {yaml,json,cbor,cborhex}] -t ENTRY_TYPE
531 [--default-max-qty DEFAULT_MAX_QTY]
532 [--yaml-compatibility]
533
534Read CBOR, YAML, or JSON data from file or stdin and validate it against a
535CDDL schema file.
536
537options:
538 -h, --help show this help message and exit
539 -c CDDL, --cddl CDDL Path to one or more input CDDL file(s). Passing
540 multiple files is equivalent to concatenating them.
541 --no-prelude Exclude the standard CDDL prelude from the build. The
542 prelude can be viewed at zcbor/cddl/prelude.cddl in
543 the repo, or together with the script.
544 -v, --verbose Print more information while parsing CDDL and
545 generating code.
546 -i INPUT, --input INPUT
547 Input data file. The option --input-as specifies how
548 to interpret the contents. Use "-" to indicate stdin.
549 --input-as {yaml,json,cbor,cborhex}
550 Which format to interpret the input file as. If
551 omitted, the format is inferred from the file name.
552 .yaml, .yml => YAML, .json => JSON, .cborhex => CBOR
553 as hex string, everything else => CBOR
554 -t ENTRY_TYPE, --entry-type ENTRY_TYPE
555 Name of the type (from the CDDL) to interpret the data
556 as.
557 --default-max-qty DEFAULT_MAX_QTY, --dq DEFAULT_MAX_QTY
558 Default maximum number of repetitions when no maximum
559 is specified. It is only relevant when handling data
560 that will be decoded by generated code. If omitted, a
561 large number will be used.
562 --yaml-compatibility Whether to convert CBOR-only values to YAML-compatible
563 ones (when converting from CBOR), or vice versa (when
564 converting to CBOR). When this is enabled, all CBOR
565 data is guaranteed to convert into YAML/JSON. JSON and
566 YAML do not support all data types that CBOR/CDDL
567 supports. bytestrings (BSTR), tags, undefined, and
568 maps with non-text keys need special handling. See the
569 zcbor README for more information.
570
571```
572
573zcbor convert --help
574--------------------
575
576```
577usage: zcbor convert [-h] -c CDDL [--no-prelude] [-v] -i INPUT
578 [--input-as {yaml,json,cbor,cborhex}] -t ENTRY_TYPE
579 [--default-max-qty DEFAULT_MAX_QTY]
580 [--yaml-compatibility] -o OUTPUT
581 [--output-as {yaml,json,cbor,cborhex,c_code}]
582 [--c-code-var-name C_CODE_VAR_NAME]
583 [--c-code-columns C_CODE_COLUMNS]
584
585Parse a CDDL file and validate/convert between CBOR and YAML/JSON. The script
586decodes the CBOR/YAML/JSON data from a file or stdin and verifies that it
587conforms to the CDDL description. The script fails if the data does not
588conform. 'zcbor validate' can be used if only validate is needed.
589
590options:
591 -h, --help show this help message and exit
592 -c CDDL, --cddl CDDL Path to one or more input CDDL file(s). Passing
593 multiple files is equivalent to concatenating them.
594 --no-prelude Exclude the standard CDDL prelude from the build. The
595 prelude can be viewed at zcbor/cddl/prelude.cddl in
596 the repo, or together with the script.
597 -v, --verbose Print more information while parsing CDDL and
598 generating code.
599 -i INPUT, --input INPUT
600 Input data file. The option --input-as specifies how
601 to interpret the contents. Use "-" to indicate stdin.
602 --input-as {yaml,json,cbor,cborhex}
603 Which format to interpret the input file as. If
604 omitted, the format is inferred from the file name.
605 .yaml, .yml => YAML, .json => JSON, .cborhex => CBOR
606 as hex string, everything else => CBOR
607 -t ENTRY_TYPE, --entry-type ENTRY_TYPE
608 Name of the type (from the CDDL) to interpret the data
609 as.
610 --default-max-qty DEFAULT_MAX_QTY, --dq DEFAULT_MAX_QTY
611 Default maximum number of repetitions when no maximum
612 is specified. It is only relevant when handling data
613 that will be decoded by generated code. If omitted, a
614 large number will be used.
615 --yaml-compatibility Whether to convert CBOR-only values to YAML-compatible
616 ones (when converting from CBOR), or vice versa (when
617 converting to CBOR). When this is enabled, all CBOR
618 data is guaranteed to convert into YAML/JSON. JSON and
619 YAML do not support all data types that CBOR/CDDL
620 supports. bytestrings (BSTR), tags, undefined, and
621 maps with non-text keys need special handling. See the
622 zcbor README for more information.
623 -o OUTPUT, --output OUTPUT
624 Output data file. The option --output-as specifies how
625 to interpret the contents. Use "-" to indicate stdout.
626 --output-as {yaml,json,cbor,cborhex,c_code}
627 Which format to interpret the output file as. If
628 omitted, the format is inferred from the file name.
629 .yaml, .yml => YAML, .json => JSON, .c, .h => C code,
630 .cborhex => CBOR as hex string, everything else =>
631 CBOR
632 --c-code-var-name C_CODE_VAR_NAME
633 Only relevant together with '--output-as c_code' or .c
634 files.
635 --c-code-columns C_CODE_COLUMNS
636 Only relevant together with '--output-as c_code' or .c
637 files. The number of bytes per line in the variable
638 instantiation. If omitted, the entire declaration is a
639 single line.
640
641```
642
