RealView® Compilation Tools Assembler Guide 7.2.9. DN and SN

7.2.9. DN and SN

The DN directive defines a name for a specified double-precision VFP register. The names d0-d15 and D0-D15 are predefined for VFPv2 and the names d16-d31 and D16-D31 are predefined for VFPv3.

The SN directive defines a name for a specified single-precision VFP register. The names s0-s31 and S0-S31 are predefined.

Syntax

name DN expr

name SN expr

where:

name: is the name to be assigned to the VFP register. name cannot be the same as any of the predefined names listed in Predefined register and coprocessor names.
expr: evaluates to a double-precision VFP register number from 0 to 15 (VFPv2) or 0 to 31 (VFPv3), or a single-precision VFP register number from 0 to 31 as appropriate.

Usage

Use DN or SN to allocate convenient names to VFP registers, to help you to remember what you use each one for.

Note

Avoid conflicting uses of the same register under different names.

You cannot specify a vector length in a DN or SN directive (see VFP directives and vector notation).

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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