Arm VERSION 1.2 Manual do Utilizador descarregar pdf (Página 254)

100

101

Vector Floating-point Programming

6.7.1 FABS, FCPY, and FNEG

Floating-point copy, absolute value, and negate.

These instructions can be scalar, vector, or mixed (see Vector and scalar operations on

page 6-7).

Syntax

<op><precision>{cond} Fd, Fm

where:

<op>

must be one of

FCPY

FABS

, or

FNEG

must be either

for single-precision, or

for double-precision.

cond

is an optional condition code (see VFP and condition codes on

page 6-8).

is the VFP register for the result.

is the VFP register holding the operand.

The precision of

and

must match the precision specified in

Usage

The

FCPY

instruction copies the contents of

into

The

FABS

instruction takes the contents of

, clears the sign bit, and places the result in

. This gives the absolute value.

The

FNEG

instruction takes the contents of

, changes the sign bit, and places the result

. This gives the negation of the value.

If the operand is a NaN, the sign bit is determined in each case as above, but no

exception is produced.

Exceptions

None of these instructions can produce any exceptions.

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