5.6.9 Comparison of resource types

It is generally clear from the context whether a piece of state that an instance exposes is an init-time parameter, a run-time parameter, or a register. If it is unclear, see the following table.

In this table, if the criterion is true, the value can be modeled as shown, reading from left to right:

Table 5-3 Comparison of resource types

Criterion

Init-time parameter Run-time parameter Register
Is configurable at initialization time. yes yes no
Is modifiable at runtime. no yes yes
Is modifiable at runtime and generally does not change at runtime except when the user changes it. no yes usually no
Can change spontaneously, that is, without a parameter write, at runtime. no no yes
Is an architectural register. no no potentially
Has a reset value. no no yes
Is reset during simulation reset. no no yes
Corresponds to a design-time parameter of the hardware. yes no no
Corresponds to a hardware register. no no potentially
Can be modified by program code. no no usually yes
Is artificial, not present in the hardware. yes yes usually no
Can have fields. no no yes
Is organized into groups. no no yes
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