View source for Data Space

'''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 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.
* 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.

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