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| <title>ConstantField - ARM Machine Readable Schema - 2.7.4</title> |
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| <div class="col-md-6 pull-left"><h1>AARCHMRS Schema <small>2.7.4</small></h1></div> |
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| <h2> |
| <span class="title-namespace">Fields.</span><span class=" title-type">ConstantField</span> |
| |
| <!-- if oneOf is set, then type is ignored --> |
| <span class="type">object</span> |
| </h2> |
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| |
| <div class="static-markdown"><p>This field represents a <code>RO</code> constant field with a specific value. For example a 4 |
| bit constant field <code>'0101'</code>.</p></div> |
| </div> |
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| <div> |
| <!-- A simple object --> |
| <h3 class="type">object</h3> |
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| <table class="table table-hover properties"> |
| <thead> |
| <tr> |
| <th class="col-md-4">Properties</th> |
| <th class="col-md-4">Type</th> |
| <th class="col-md-4">Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| |
| <!-- properties --> |
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| |
| <tr id="/properties/_meta" class="property"> |
| <th class="col-md-4"> |
| <a href="#/properties/_meta">_meta</a> |
| </th> |
| <td class="col-md-4"> |
| <a href="../Meta_schema.html" class="schema_link">Meta</a> |
| </td> |
| <td class="col-md-4"> |
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| <div> |
| See |
| <a href="../Meta_schema.html" class="schema_link">Meta</a> |
| for more information. |
| </div> |
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| </td> |
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| |
| <tr id="/properties/_type" class="property"> |
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| <a href="#/properties/_type">_type</a> |
| </th> |
| <td class="col-md-4"> |
| </td> |
| <td class="col-md-4"> |
| <dl> |
| <dt>Enum</dt> |
| <dd> |
| <code>Fields.ConstantField</code> |
| </dd> |
| </dl> |
| |
| |
| |
| </td> |
| </tr> |
| |
| <tr id="/properties/access" class="property"> |
| <th class="col-md-4"> |
| <a href="#/properties/access">access</a> |
| </th> |
| <td class="col-md-4"> |
| <a href="../Traits/HasFieldAccess_schema.html#/definitions/access" class="schema_link">Traits.HasFieldAccess</a> |
| </td> |
| <td class="col-md-4"> |
| <div><p>Constant fields are by nature <code>RO</code> in an implementation. |
| This means that once implemented, the value cannot be changed. However in some cases, |
| software reads may return another value.</p> |
| <p>For example, a constant value with the value of <code>1</code> may have a |
| Read-As-Zero accessor (RAZ), meaning that even though the value is set to |
| <code>1</code> software must interpret it as <code>0</code>.</p> |
| <p>Note:</p> |
| <ul> |
| <li>The write counterpart of the access must always be <code>WI</code> as |
| <code>ConstantFields</code> are not writable.</li> |
| <li>If the value of access is set to null (or omitted), then |
| <code>RO/WI</code> is implied.</li> |
| </ul></div> |
| |
| <div> |
| See |
| <a href="../Traits/HasFieldAccess_schema.html#/definitions/access" class="schema_link">definitions.access</a> in |
| <a href="../Traits/HasFieldAccess_schema.html#/definitions/access" class="schema_link">Traits.HasFieldAccess</a> |
| for more information. |
| </div> |
| |
| <div> |
| <b>Default</b> |
| <pre class="schema-json"><code class="language-json">null</code></pre> |
| </div> |
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| </td> |
| </tr> |
| |
| <tr id="/properties/description" class="property"> |
| <th class="col-md-4"> |
| <a href="#/properties/description">description</a> |
| </th> |
| <td class="col-md-4"> |
| <a href="../Traits/HasDescription_schema.html#/definitions/description" class="schema_link">Traits.HasDescription</a> |
| </td> |
| <td class="col-md-4"> |
| |
| <div> |
| See |
| <a href="../Fields/Field_schema.html#/properties/description" class="schema_link">properties.description</a> in |
| <a href="../Fields/Field_schema.html#/properties/description" class="schema_link">Fields.Field</a> |
| for more information. |
| </div> |
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| </td> |
| </tr> |
| |
| <tr id="/properties/name" class="property"> |
| <th class="col-md-4"> |
| <a href="#/properties/name">name</a> |
| </th> |
| <td class="col-md-4"> |
| <ul class="inline list-type"> |
| <li class="inline type">string</li> |
| <li class="inline type">null</li> |
| </ul> |
| </td> |
| <td class="col-md-4"> |
| |
| <div> |
| See |
| <a href="../Fields/Field_schema.html#/properties/name" class="schema_link">properties.name</a> in |
| <a href="../Fields/Field_schema.html#/properties/name" class="schema_link">Fields.Field</a> |
| for more information. |
| </div> |
| |
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| </td> |
| </tr> |
| |
| <tr id="/properties/rangeset" class="property"> |
| <th class="col-md-4"> |
| <a href="#/properties/rangeset">rangeset<sup>◊</sup></a> |
| </th> |
| <td class="col-md-4"> |
| <a href="../Rangeset_schema.html" class="schema_link">Rangeset</a> |
| </td> |
| <td class="col-md-4"> |
| |
| <div> |
| See |
| <a href="../Fields/Field_schema.html#/properties/rangeset" class="schema_link">properties.rangeset</a> in |
| <a href="../Fields/Field_schema.html#/properties/rangeset" class="schema_link">Fields.Field</a> |
| for more information. |
| </div> |
| |
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| </td> |
| </tr> |
| |
| <tr id="/properties/value" class="property"> |
| <th class="col-md-4"> |
| <a href="#/properties/value">value<sup>◊</sup></a> |
| </th> |
| <td class="col-md-4"> |
| <div><span class="type Xof">oneOf</span> [</div> |
| |
| |
| |
| |
| <div class="items-oneOf"> |
| <a href="../Values/Value_schema.html" class="schema_link">Values.Value</a> |
| </div> |
| <div class="items-oneOf"> |
| <a href="../Values/ImplementationDefined_schema.html" class="schema_link">Values.ImplementationDefined</a> |
| </div> |
| |
| |
| <div>]</div> |
| </td> |
| <td class="col-md-4"> |
| <div><p>The constant value of this ConstantField, which can be:</p> |
| <ul> |
| <li>A single <code>Value</code> (or string) such as <code>'0000'</code></li> |
| <li>An IMPLEMENTATION DEFINED value, which:<ul> |
| <li>can be open ended to any value that fits within the size of this field.</li> |
| <li>or restricted to a set of allowed constraints defined by the architecture.</li> |
| </ul> |
| </li> |
| </ul></div> |
| |
| <div> |
| |
| <!-- Can be one of following objects --> |
| |
| |
| <div class="item-type"> |
| <span><span class="type Xof">oneOf</span> <a class="title-type" href="../Values/Value_schema.html">Values.Value</a></span> |
| |
| |
| </div> |
| <div class="item-type"> |
| <span><span class="type Xof">oneOf</span> <a class="title-type" href="../Values/ImplementationDefined_schema.html">Values.ImplementationDefined</a></span> |
| |
| |
| </div> |
| |
| </div> |
| |
| |
| <h5>Examples</h5> |
| <div> |
| <pre class="schema-json"><code class="language-json">{ |
| "_type": "Values.Value", |
| "value": "'00'", |
| "meaning": "A defined constant value with a custom meaning" |
| }</code></pre> |
| <pre class="schema-json"><code class="language-json">{ |
| "_type": "Values.ImplementationDefined", |
| "constraints": { |
| "'00'": "A possible value chosen by an implementation.", |
| "'01'": "A second possible value chosen by an implementation." |
| } |
| }</code></pre> |
| </div> |
| |
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| |
| </td> |
| </tr> |
| |
| |
| <!-- patternProperties --> |
| |
| <!-- object property attributes --> |
| <tr> |
| <td colspan="3"> |
| <dl> |
| <dt>Additional Properties</dt> |
| <dd>Not Allowed</dd> |
| </dl> |
| </td> |
| </tr> |
| |
| <tr> |
| <td colspan="3"> |
| <dl> |
| <dt>◊ Required</dt> |
| <dd>Properties marked with ◊ are required properties.</dd> |
| </dl> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| |
| |
| |
| |
| <!-- array, and it has described items --> |
| </div> |
| |
| |
| <h5>Examples</h5> |
| <div> |
| <pre class="schema-json"><code class="language-json">{ |
| "_type": "Fields.ConstantField", |
| "name": "C1", |
| "rangeset": [ |
| { |
| "_type": "Range", |
| "start": 0, |
| "width": 2 |
| } |
| ], |
| "description": { |
| "_type": "Description", |
| "after": null, |
| "before": "A constant field that does not change its value during runtime" |
| }, |
| "value": { |
| "_type": "Values.Value", |
| "value": "'00'", |
| "meaning": null |
| } |
| }</code></pre> |
| <pre class="schema-json"><code class="language-json">{ |
| "_type": "Fields.ConstantField", |
| "name": "C2", |
| "rangeset": [ |
| { |
| "_type": "Range", |
| "start": 0, |
| "width": 2 |
| } |
| ], |
| "description": { |
| "_type": "Description", |
| "after": null, |
| "before": "Constant value with possible architecture values which must be configured during an implementation" |
| }, |
| "value": { |
| "_type": "Values.ImplementationDefined", |
| "constraints": { |
| "_type": "Valuesets.Values", |
| "values": [ |
| { |
| "_type": "Values.Value", |
| "value": "'00'", |
| "meaning": "A possible value chosen by an implementation." |
| }, |
| { |
| "_type": "Values.Value", |
| "value": "'01'", |
| "meaning": "A second possible value chosen by an implementation." |
| } |
| ] |
| } |
| } |
| }</code></pre> |
| </div> |
| |
| |
| |
| |
| </div> |
| |
| <div class="row schema"> |
| <h3>Schema <small><a href="http://json-schema.org/draft-04/schema#">http://json-schema.org/draft-04/schema#</a></small></h3> |
| <pre class="schema-json"><code class="language-json">{ |
| "additionalProperties": false, |
| "info": [ |
| [ |
| "This field represents a `RO` constant field with a specific value. For example a 4", |
| "bit constant field `'0101'`." |
| ] |
| ], |
| "properties": { |
| "_meta": { |
| "$ref": "../Meta.json" |
| }, |
| "_type": { |
| "enum": [ |
| "Fields.ConstantField" |
| ] |
| }, |
| "name": { |
| "see": "../Fields/Field.json", |
| "type": [ |
| "string", |
| "null" |
| ] |
| }, |
| "rangeset": { |
| "see": "../Fields/Field.json", |
| "$ref": "../Rangeset.json" |
| }, |
| "value": { |
| "info": [ |
| "The constant value of this ConstantField, which can be:", |
| [ |
| " - A single `Value` (or string) such as `'0000'`", |
| " - An IMPLEMENTATION DEFINED value, which:", |
| " - can be open ended to any value that fits within the size of this field.", |
| " - or restricted to a set of allowed constraints defined by the architecture." |
| ] |
| ], |
| "oneOf": [ |
| { |
| "$ref": "../Values/Value.json" |
| }, |
| { |
| "$ref": "../Values/ImplementationDefined.json" |
| } |
| ], |
| "examples": [ |
| { |
| "_type": "Values.Value", |
| "value": "'00'", |
| "meaning": "A defined constant value with a custom meaning" |
| }, |
| { |
| "_type": "Values.ImplementationDefined", |
| "constraints": { |
| "'00'": "A possible value chosen by an implementation.", |
| "'01'": "A second possible value chosen by an implementation." |
| } |
| } |
| ] |
| }, |
| "access": { |
| "default": null, |
| "$ref": "../Traits/HasFieldAccess.json#/definitions/access", |
| "info": [ |
| [ |
| "Constant fields are by nature `RO` in an implementation. ", |
| "This means that once implemented, the value cannot be changed. However in some cases,", |
| "software reads may return another value." |
| ], |
| [ |
| "For example, a constant value with the value of `1` may have a ", |
| "Read-As-Zero accessor (RAZ), meaning that even though the value is set to ", |
| "`1` software must interpret it as `0`." |
| ], |
| "Note:", |
| [ |
| " - The write counterpart of the access must always be `WI` as ", |
| " `ConstantFields` are not writable.", |
| " - If the value of access is set to null (or omitted), then ", |
| " `RO/WI` is implied." |
| ] |
| ] |
| }, |
| "description": { |
| "$ref": "../Traits/HasDescription.json#/definitions/description", |
| "see": "../Fields/Field.json" |
| } |
| }, |
| "required": [ |
| "value", |
| "rangeset" |
| ], |
| "title": "ConstantField", |
| "type": "object", |
| "examples": [ |
| { |
| "_type": "Fields.ConstantField", |
| "name": "C1", |
| "rangeset": [ |
| { |
| "_type": "Range", |
| "start": 0, |
| "width": 2 |
| } |
| ], |
| "description": { |
| "_type": "Description", |
| "after": null, |
| "before": "A constant field that does not change its value during runtime" |
| }, |
| "value": { |
| "_type": "Values.Value", |
| "value": "'00'", |
| "meaning": null |
| } |
| }, |
| { |
| "_type": "Fields.ConstantField", |
| "name": "C2", |
| "rangeset": [ |
| { |
| "_type": "Range", |
| "start": 0, |
| "width": 2 |
| } |
| ], |
| "description": { |
| "_type": "Description", |
| "after": null, |
| "before": "Constant value with possible architecture values which must be configured during an implementation" |
| }, |
| "value": { |
| "_type": "Values.ImplementationDefined", |
| "constraints": { |
| "_type": "Valuesets.Values", |
| "values": [ |
| { |
| "_type": "Values.Value", |
| "value": "'00'", |
| "meaning": "A possible value chosen by an implementation." |
| }, |
| { |
| "_type": "Values.Value", |
| "value": "'01'", |
| "meaning": "A second possible value chosen by an implementation." |
| } |
| ] |
| } |
| } |
| } |
| ], |
| "$schema": "http://json-schema.org/draft-04/schema#" |
| }</code></pre> |
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