VHDL component instantiation

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shaiko

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Is it possible to put a component inside a package ?
If so, what is the correct syntax to instatiate it ?
 

shaiko said:
Is it possible to put a component inside a package ?
If so, what is the correct syntax to instatiate it ?
Click to expand...
The best place to put a component is inside a package...in the same file as the entity. So if you have an entity called 'Widget', the entity would be...
Code: 
[LEFT][TABLE="class: vhdl syntaxHighlighter expand"]
[TR]
[TD="colspan: 2"]Code VHDL - [[COLOR=#226c22]expand[/COLOR]][/TD]
[/TR]
[TR="class: li1"]
[TD]
123[/TD]
[TD]
[COLOR=#000080][B]entity[/B][/COLOR] Widget [COLOR=#000080][B]is[/B][/COLOR] ...[COLOR=#000080][B]end[/B][/COLOR] Widget[COLOR=#000066];[/COLOR][/TD]
[/TR]
[/TABLE]
[/LEFT]

You would have a component definition like this...
Code: 
[LEFT][TABLE="class: vhdl syntaxHighlighter expand"]
[TR]
[TD="colspan: 2"]Code VHDL - [[COLOR=#226c22]expand[/COLOR]][/TD]
[/TR]
[TR="class: li1"]
[TD]
123[/TD]
[TD]
[COLOR=#000080][B]component[/B][/COLOR] Widget [COLOR=#000080][B]is[/B][/COLOR] ...[COLOR=#000080][B]end[/B][/COLOR] [COLOR=#000080][B]component[/B][/COLOR] Widget[COLOR=#000066];[/COLOR][/TD]
[/TR]
[/TABLE]
[/LEFT]

Which you could then put into a package like this...

Code: 
[LEFT][TABLE="class: vhdl syntaxHighlighter expand"]
[TR]
[TD="colspan: 2"]Code VHDL - [[COLOR=#226c22]expand[/COLOR]][/TD]
[/TR]
[TR="class: li1"]
[TD]
12345[/TD]
[TD]
[COLOR=#000080][B]package[/B][/COLOR] pkg_Widget    [COLOR=#000080][B]component[/B][/COLOR] Widget [COLOR=#000080][B]is[/B][/COLOR]     ...    [COLOR=#000080][B]end[/B][/COLOR] [COLOR=#000080][B]component[/B][/COLOR] Widget[COLOR=#000066];[/COLOR][COLOR=#000080][B]end[/B][/COLOR] [COLOR=#000080][B]package[/B][/COLOR] pkg_Widget[/TD]
[/TR]
[/TABLE]
[/LEFT]

To use the Widget, you would instantiate it like this....

Code: 
[LEFT][TABLE="class: vhdl syntaxHighlighter expand"]
[TR]
[TD="colspan: 2"]Code VHDL - [[COLOR=#226c22]expand[/COLOR]][/TD]
[/TR]
[TR="class: li1"]
[TD]
123456[/TD]
[TD]
[COLOR=#000080][B]use[/B][/COLOR] [COLOR=#0000ff]work[/COLOR].pkg_Widget.[COLOR=#000080][B]all[/B][/COLOR][COLOR=#000066];[/COLOR]...[COLOR=#000080][B]architecture[/B][/COLOR] rtl [COLOR=#000080][B]of[/B][/COLOR] Use_The_Widget [COLOR=#000080][B]is[/B][/COLOR][COLOR=#000080][B]begin[/B][/COLOR]   The_Widget [COLOR=#000066]:[/COLOR] widget [COLOR=#000080][B]generic[/B][/COLOR] [COLOR=#000080][B]map[/B][/COLOR][COLOR=#000066]([/COLOR]...[COLOR=#000066])[/COLOR] [COLOR=#000080][B]port[/B][/COLOR] [COLOR=#000080][B]map[/B][/COLOR][COLOR=#000066]([/COLOR]...[COLOR=#000066])[/COLOR][COLOR=#000066];[/COLOR][COLOR=#000080][B]end[/B][/COLOR] rtl[COLOR=#000066];[/COLOR][/TD]
[/TR]
[/TABLE]
[/LEFT]

However, an even better way is to not even bother with components. They provide value in only a few specialized cases, for the most part they are just a near duplicate of the entity which then you need to manually make sure they stay the same (i.e. change a signal type, do it in both places; add or subtract a signal, do it in both places). While keeping the component and entity in the same file facilitates making the changes it is still unneeded work. Same example, but this time no component definition, you would instantiate it like this...

Code: 
[LEFT][TABLE="class: vhdl syntaxHighlighter expand"]
[TR]
[TD="colspan: 2"]Code VHDL - [[COLOR=#226c22]expand[/COLOR]][/TD]
[/TR]
[TR="class: li1"]
[TD]
123456[/TD]
[TD]
...[COLOR=#000080][B]architecture[/B][/COLOR] rtl [COLOR=#000080][B]of[/B][/COLOR] Use_The_Widget [COLOR=#000080][B]is[/B][/COLOR][COLOR=#000080][B]begin[/B][/COLOR]   The_Widget [COLOR=#000066]:[/COLOR] [COLOR=#000080][B]entity[/B][/COLOR] [COLOR=#0000ff]work[/COLOR].widget [COLOR=#000080][B]generic[/B][/COLOR] [COLOR=#000080][B]map[/B][/COLOR][COLOR=#000066]([/COLOR]...[COLOR=#000066])[/COLOR] [COLOR=#000080][B]port[/B][/COLOR] [COLOR=#000080][B]map[/B][/COLOR][COLOR=#000066]([/COLOR]...[COLOR=#000066])[/COLOR][COLOR=#000066];[/COLOR][COLOR=#000080][B]end[/B][/COLOR] rtl[COLOR=#000066];[/COLOR][/TD]
[/TR]
[/TABLE]
[/LEFT]

Much simpler, less to go wrong.

Kevin Jennings
 
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