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DN and SN

12.23 DN and SN

The DN and SN directives define names for VFP registers.

Syntax

name directive expr{.type}
where:
name
is the name to be assigned to the extension register. name cannot be the same as any of the predefined names.
directive
is DN or SN.
expr
Can be:
  • An expression that evaluates to a number in the range:
    • 0-15 if you are using DN in VFPv2.
    • 0-31 otherwise.
  • A predefined register name, or a register name that has already been defined in a previous directive.
type
is any VFP datatype.
type is Extended notation.

Usage

Use DN or SN to allocate convenient names to extension registers, to help you to remember what you use each one for.
The DN directive defines a name for a specified 64-bit extension register.
The SN directive defines a name for a specified single-precision VFP register.

Note

Avoid conflicting uses of the same register under different names.
You cannot specify a vector length in a DN or SN directive.

Examples

energy  DN  6   ; defines energy as a symbol for VFP double-precision register 6
mass    SN  16  ; defines mass as a symbol for VFP single-precision register 16
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