Encoding:

COP1

010001

fmt

0

00000

fs

fd

RECIP1

011101

6

5

5

5

5

6

Format: 

RECIP1.fmt

Floating Point Reduced Precision Reciprocal (Sequence Step 1)

RECIP1.S fd,fs

MIPS-3D

Floating Point Reduced Precision Reciprocal (Sequence Step 1)

RECIP1.D fd,fs

MIPS-3D

Floating Point Reduced Precision Reciprocal (Sequence Step 1)

RECIP1.PS fd,fs

MIPS-3D

Floating Point Reduced Precision Reciprocal (Sequence Step 1)

Purpose:

Floating Point Reduced Precision Reciprocal (Sequence Step 1)

Generate a reduced-precision reciprocal of one or two FP values

Description: 

FPR[fd] = 1.0 / FPR[fs]

The reciprocal of the value in FPR fs is approximated and placed in FPR fd. The operand and result are values in format S, D, or PS.

The numeric accuracy of this operation is implementation dependent;it does not meetthe accuracy specified by the

IEEE 754 Floating Point standard. A minimum accuracy of 14 bits is recommended for both the S and D input data formats.

It is implementation dependent whether the result is affected by the current rounding mode in FCSR. This instruction is meant to operate in RN (round to nearest) mode for the best accuracy. It is also meant to operate in the Flush to

Zero (FS=0) mode. In this mode, if the incoming data is in the denormalized range, it is assumed to be zero, and if the output is in the denormalized range, it is forced to zero.

In addition, if the input to this instruction is zero, the output is not infinity, but the maximum normalized value. This property is useful for 3D graphics applications. If the input is infinity, the output is zero.

This instruction is used as the first step of an instruction sequence that can be used to produce a full precision reciprocal value. See the description of RECIP2.fmt for an example of how to use this instruction in a code sequence to produce a full precision reciprocal result.

Restrictions:

is UNPRE-The fields fs and fd must specify FPRs valid for operands oftype fmt.Ifthey are not valid,the result

DICTABLE. The format of the data in the specified operand register fs must be a value in format fmt; if it is not, the

result is UNPREDICTABLE and the value of the operand FPR becomes UNPREDICTABLE.

Operation: 

StoreFPR(fd, fmt, (1.0 / ValueFPR(fs, fmt))ReducedPrecision)

Exceptions:

Coprocessor Unusable, Reserved Instruction

Floating Point Exceptions:

Unimplemented Operation, Invalid Operation, Overflow, Inexact, Underflow, Division-by-zero