18.4 FCCMP

Floating-point Conditional quiet Compare (scalar).

Syntax

FCCMP Hn, Hm, #nzcv, cond ; Half-precision

FCCMP Sn, Sm, #nzcv, cond ; Single-precision

FCCMP Dn, Dm, #nzcv, cond ; Double-precision

Where:

Hn
Is the 16-bit name of the first SIMD and FP source register.
Hm
Is the 16-bit name of the second SIMD and FP source register.
Sn
Is the 32-bit name of the first SIMD and FP source register.
Sm
Is the 32-bit name of the second SIMD and FP source register.
Dn
Is the 64-bit name of the first SIMD and FP source register.
Dm
Is the 64-bit name of the second SIMD and FP source register.
nzcv
Is the flag bit specifier, an immediate in the range 0 to 15, giving the alternative state for the 4-bit NZCV condition flags.
cond
Is one of the standard conditions.

NaNs

The IEEE 754 standard specifies that the result of a comparison is precisely one of <, ==, > or unordered. If either or both of the operands are NaNs, they are unordered, and all three of (Operand1 < Operand2), (Operand1 == Operand2) and (Operand1 > Operand2) are false. This case results in the FPSCR flags being set to N=0, Z=0, C=1, and V=1.

Operation

Floating-point Conditional quiet Compare (scalar). This instruction compares the two SIMD and FP source register values and writes the result to the PSTATE.{N, Z, C, V} flags. If the condition does not pass then the PSTATE.{N, Z, C, V} flags are set to the flag bit specifier.

It raises an Invalid Operation exception only if either operand is a signaling NaN.

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 in the Arm® Architecture Reference Manual Arm®v8, for Arm®v8‑A architecture profile.

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.

flags = if cond then compareQuiet(Vn,Vm) else #nzcv.

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