FMULX (by element)

Floating-point Multiply extended (by element). This instruction multiplies the floating-point values in the vector elements in the first source SIMD&FP register by the specified floating-point value in the second source SIMD&FP register, places the results in a vector, and writes the vector to the destination SIMD&FP register.

If one value is zero and the other value is infinite, the result is 2.0. In this case, the result is negative if only one of the values is negative, otherwise the result is positive.

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 idxdsize = if H == '1' then 128 else 64; integer n = UInt(Rn); integer m = UInt(Rm); integer d = UInt(Rd); integer index = UInt(H:L:M); integer esize = 16; integer datasize = esize; integer elements = 1; boolean mulx_op = (U == '1');

Scalar, single-precision and double-precision

integer idxdsize = if H == '1' then 128 else 64; integer index; bit Rmhi = M; case sz:L of when '0x' index = UInt(H:L); when '10' index = UInt(H); when '11' UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rmhi:Rm); integer esize = 32 << UInt(sz); integer datasize = esize; integer elements = 1; boolean mulx_op = (U == '1');

Vector, half-precision
(FEAT_FP16)

if !HaveFP16Ext() then UNDEFINED; integer idxdsize = if H == '1' then 128 else 64; integer n = UInt(Rn); integer m = UInt(Rm); integer d = UInt(Rd); integer index = UInt(H:L:M); integer esize = 16; integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize; boolean mulx_op = (U == '1');

Vector, single-precision and double-precision

integer idxdsize = if H == '1' then 128 else 64; integer index; bit Rmhi = M; case sz:L of when '0x' index = UInt(H:L); when '10' index = UInt(H); when '11' UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rmhi: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; boolean mulx_op = (U == '1');