FRSQRTS

Floating-point Reciprocal Square Root Step. This instruction multiplies corresponding floating-point values in the vectors of the two source SIMD&FP registers, subtracts each of the products from 3.0, divides these results by 2.0, places the results into a vector, and writes the vector to the destination SIMD&FP register.

This instruction can generate a floating-point exception. Depending on the settings in FPCR, the exception results in either a flag being set in FPSR, or a synchronous exception being generated. For more information, see Floating-point exception traps.

Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.

It has encodings from 4 classes: Scalar half precision , Scalar single-precision and double-precision , Vector half precision and Vector single-precision and double-precision

Scalar half precision
(FEAT_FP16)

if !HaveFP16Ext() then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer esize = 16; integer datasize = esize; integer elements = 1;

Scalar single-precision and double-precision

integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer esize = 32 << UInt(sz); integer datasize = esize; integer elements = 1;

Vector half precision
(FEAT_FP16)

if !HaveFP16Ext() then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer esize = 16; integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize;

Vector single-precision and double-precision

integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); if sz:Q == '10' then UNDEFINED; integer esize = 32 << UInt(sz); integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize;