125 lines
2.5 KiB
Markdown
125 lines
2.5 KiB
Markdown
# Schema Format
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_**Supported syntaxes: JSON, XML, YAML**_
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The following description uses the JSON syntax
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For examples in different formats, see [example1.yaml](example1.yaml), [example2.yaml](example2.yaml), [example3.json](example3.json) and [example4.xml](example4.xml).
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## Main layout
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A schema contains a dictionary of structures. There must be at least one defined structure named "main"
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```json
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{
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"structures": {
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"main": {
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...
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},
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"struct1": {
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...
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},
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"struct2": {
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...
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},
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...
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}
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}
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```
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## Structure
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A structure has a given number of bits and one or multiple ranges. Each range of bits can have a name, a description and / or values with special meaning (see [Range](#range)). A range's structure can also depend on another range's value (see [Dependencies](#dependencies))
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The range name (or key) defines the left- and rightmost bits (e.g. 7-4 goes from bit 7 to bit 4). Bits are displayed in big-endian, i.e. the leftmost bit has the highest value.
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```json
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"main": {
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"bits": 8,
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"ranges": {
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"7-4": {
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...
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},
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"3-2": {
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...
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},
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"1": {
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...
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},
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"0": {
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...
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}
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}
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}
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```
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## Range
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A range represents a group of consecutive bits. It can have a name (display in the bit cells), a description (displayed under the structure) and / or values.
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For values depending on other ranges, see [Dependencies](#dependencies).
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> **Note**<br>
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> In YAML, make sure to wrap values in quotes because some values can be interpreted as octal notation (e.g. 010)
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```json
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"3-2": {
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"name": "op",
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"description": "Logical operation",
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"values": {
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"00": "AND",
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"01": "OR",
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"10": "XOR",
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"11": "NAND"
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}
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}
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```
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## Dependencies
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The structure of one range may depend on the value of another. To represent this situation, first indicate on the child range the range on which it depends:
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```json
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"7-4": {
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...
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"depends-on": "0"
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}
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```
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Then, in its values, indicate which structure to use. A description can also be added (displayed above the horizontal dependency arrow)
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```json
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"7-4": {
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...
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"depends-on": "0",
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"values": {
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"0": {
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"description": "immediate value",
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"structure": "immediateValue"
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},
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"1": {
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"description": "value in register",
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"structure": "registerValue"
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}
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}
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}
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```
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Finally, add the sub-structures to the structure dictionary:
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```json
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{
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"structures": {
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"main": {
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...
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},
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"immediateValue": {
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"bits": 4,
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...
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},
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"registerValue": {
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"bits": 4,
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...
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},
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...
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}
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}
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``` |