Data Space - Revision history

Mefistotelis: typo

2020-06-10T18:54:15Z

typo

← Older revision		Revision as of 18:54, 10 June 2020
Line 13:		Line 13:
	Offsets of specific items within ''data space'' block do not change when values within data are modified. This means that any variable size values (ie. strings) are not stored directly in the continuous ''data space'', but are allocated separately and ''data space'' only contains pointer to the real data. This means that data space is size invariant, as long as Type Map remains unchanged.		Offsets of specific items within ''data space'' block do not change when values within data are modified. This means that any variable size values (ie. strings) are not stored directly in the continuous ''data space'', but are allocated separately and ''data space'' only contains pointer to the real data. This means that data space is size invariant, as long as Type Map remains unchanged.

	''Data space'' of a [[VI\|VI file]] can be viewed in detail within [[Heap ~~Peak~~]] window.		''Data space'' of a [[VI\|VI file]] can be viewed in detail within [[Heap Peek]] window.

	[[Category:LabVIEW internals\|LV internal]]		[[Category:LabVIEW internals\|LV internal]]
	[[Category:LabVIEW internals]]		[[Category:LabVIEW internals]]

Mefistotelis: ref to heap peek

2020-06-10T18:53:51Z

ref to heap peek

← Older revision		Revision as of 18:53, 10 June 2020
Line 12:		Line 12:

	Offsets of specific items within ''data space'' block do not change when values within data are modified. This means that any variable size values (ie. strings) are not stored directly in the continuous ''data space'', but are allocated separately and ''data space'' only contains pointer to the real data. This means that data space is size invariant, as long as Type Map remains unchanged.		Offsets of specific items within ''data space'' block do not change when values within data are modified. This means that any variable size values (ie. strings) are not stored directly in the continuous ''data space'', but are allocated separately and ''data space'' only contains pointer to the real data. This means that data space is size invariant, as long as Type Map remains unchanged.

			''Data space'' of a [[VI\|VI file]] can be viewed in detail within [[Heap Peak]] window.

	[[Category:LabVIEW internals\|LV internal]]		[[Category:LabVIEW internals\|LV internal]]
	[[Category:LabVIEW internals]]		[[Category:LabVIEW internals]]

Mefistotelis: paragraph on invariant ds

2020-06-10T18:51:56Z

paragraph on invariant ds

← Older revision		Revision as of 18:51, 10 June 2020
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	Some of the types stored in ''Data Space'' are not linked directly to user created code, and are LV internal data instead. For example, the data space always contains a block of 51 integer values - these are settings internal to LabVIEW, called [[DSInit Table]]. It also contains a list of [[DCO]]s - objects which contain selected properties of controls and indicators from [[Front Panel]], and are retained even when FP is removed form VI file.		Some of the types stored in ''Data Space'' are not linked directly to user created code, and are LV internal data instead. For example, the data space always contains a block of 51 integer values - these are settings internal to LabVIEW, called [[DSInit Table]]. It also contains a list of [[DCO]]s - objects which contain selected properties of controls and indicators from [[Front Panel]], and are retained even when FP is removed form VI file.

			Offsets of specific items within ''data space'' block do not change when values within data are modified. This means that any variable size values (ie. strings) are not stored directly in the continuous ''data space'', but are allocated separately and ''data space'' only contains pointer to the real data. This means that data space is size invariant, as long as Type Map remains unchanged.

	[[Category:LabVIEW internals\|LV internal]]		[[Category:LabVIEW internals\|LV internal]]
	[[Category:LabVIEW internals]]		[[Category:LabVIEW internals]]

Mefistotelis: refs

2020-06-10T18:43:12Z

refs

← Older revision		Revision as of 18:43, 10 June 2020
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	Longer explanation:		Longer explanation:
	* Like in all languages, you can define [[Data type\|data types]] in [[LabVIEW]]. You don't need any action to define boolean - you just place the [[control]] which uses it, and ''data type'' is added automatically. But compound types, like Clusters and Arrays - these you need to define manually.		* Like in all languages, you can define [[Data type\|data types]] in [[LabVIEW]]. You don't need any action to define [[Boolean data type\|boolean]] - you just place the [[control]] which uses it, and ''data type'' is added automatically. But compound types, like [[Cluster data type\|Clusters]] and Arrays - these you need to define manually.
	* LV stores all [[Data type\|data types]] used within a [[VI]] in form of [[Type descriptor\|Type Descriptors]] ('''TD'''s). There is a table of these in every VI file.		* LV stores all [[Data type\|data types]] used within a [[VI]] in form of [[Type descriptor\|Type Descriptors]] ('''TD'''s). There is a table of these in every VI file.
	* When an instance of data type is required - real variable needs to be created - the '''TD''' is added to '''Type Map'''. Type Map is just another table, which maps TDs into Data Space. That '''Type Map Entry''' is a confirmation that there is an area reserved in ''Data Space'' for the variable, and it also points to the specific place where data starts.		* When an instance of data type is required - real variable needs to be created - the '''TD''' is added to '''Type Map'''. Type Map is just another table, which maps TDs into Data Space. That '''Type Map Entry''' is a confirmation that there is an area reserved in ''Data Space'' for the variable, and it also points to the specific place where data starts.
Line 10:		Line 10:

	Some of the types stored in ''Data Space'' are not linked directly to user created code, and are LV internal data instead. For example, the data space always contains a block of 51 integer values - these are settings internal to LabVIEW, called [[DSInit Table]]. It also contains a list of [[DCO]]s - objects which contain selected properties of controls and indicators from [[Front Panel]], and are retained even when FP is removed form VI file.		Some of the types stored in ''Data Space'' are not linked directly to user created code, and are LV internal data instead. For example, the data space always contains a block of 51 integer values - these are settings internal to LabVIEW, called [[DSInit Table]]. It also contains a list of [[DCO]]s - objects which contain selected properties of controls and indicators from [[Front Panel]], and are retained even when FP is removed form VI file.

			[[Category:LabVIEW internals\|LV internal]]
			[[Category:LabVIEW internals]]

Mefistotelis: initial page

2020-06-10T18:39:11Z

initial page

New page

'''Data Space''' is a continuous block of memory, existing for each [[VI|VI file]], which stores values of instantiated [[data type]]s.

''Data Space'' contains filling for all data elements. The data elements are instances of [[data type]]s defined by [[Type descriptor]]s. Type map is used to assign place in ''Data Space'' for [[Type descriptor]]s.

Longer explanation:
* Like in all languages, you can define [[Data type|data types]] in [[LabVIEW]]. You don't need any action to define boolean - you just place the [[control]] which uses it, and ''data type'' is added automatically. But compound types, like Clusters and Arrays - these you need to define manually.
* LV stores all [[Data type|data types]] used within a [[VI]] in form of [[Type descriptor|Type Descriptors]] ('''TD'''s). There is a table of these in every VI file.
* When an instance of data type is required - real variable needs to be created - the '''TD''' is added to '''Type Map'''. Type Map is just another table, which maps TDs into Data Space. That '''Type Map Entry''' is a confirmation that there is an area reserved in ''Data Space'' for the variable, and it also points to the specific place where data starts.
* ''Data Space'' is a continuous block of memory, which consists only of data. Reading ''Data Space'' requires information of what is stored where - so Type Map Entries are required to give meaning to the binary values stored in Data Space.

Some of the types stored in ''Data Space'' are not linked directly to user created code, and are LV internal data instead. For example, the data space always contains a block of 51 integer values - these are settings internal to LabVIEW, called [[DSInit Table]]. It also contains a list of [[DCO]]s - objects which contain selected properties of controls and indicators from [[Front Panel]], and are retained even when FP is removed form VI file.