FRECPE

Floating-point Reciprocal Estimate. This instruction finds an approximate reciprocal estimate for each vector element in the source SIMD&FP register, places the result in 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 !IsFeatureImplemented(FEAT_FP16) then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); constant integer esize = 16; constant integer datasize = esize; integer elements = 1;

Scalar single-precision and double-precision

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

Vector half precision
(FEAT_FP16)

if !IsFeatureImplemented(FEAT_FP16) then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); constant integer esize = 16; constant integer datasize = 64 << UInt(Q); integer elements = datasize DIV esize;

Vector single-precision and double-precision

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