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Fseedr square root fseedr reciprocal approximation – Motorola DSP96002 User Manual

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DSP96002 USER’S MANUAL

MOTOROLA

FSEEDR

Square Root

FSEEDR

Reciprocal Approximation

Operation:

Approximation(1/SQRT(S))

D

Assembler Syntax:

FSEEDR S,D

Description:

Take the contents of the specified source operand S, determine an approximation to sqrt(1.0/S), and store

the result in the destination operand D. The 9 MSBs of the destination significand are determined by using

a lookup ROM. The remaining bits of the significand are zeroed. This instruction is useful for initializing

floating-point square root algorithms.

The table below describes the operation of the FSEEDR instruction:

Source Operand

Result

SNaN or QNaN

QNaN

less than zero

QNaN

+/- zero

+/- zero

+ denormalized

normalized, then FSEEDR approximation

+ normalized

FSEEDR approximation

+ infinity

+ infinity

Input Operand(s) Precision: SEP Floating-Point.

Output Operand Precision: SEP Floating-Point.

CCR Condition Codes:

C

- Not affected.

V

- Not affected.

Z

- Set if result is zero. Cleared otherwise.

N

- Set if result is negative. Cleared otherwise.

I

- Set if result is infinity. Cleared otherwise.

LR

- Not affected.

R

- Not affected.

A

- Not affected.