Fill From Lowest Set Bit

Encoding

Description

The BLSFILL instruction sets, from the source operand, all cleared bits up to the lowest set bit. The result is stored in the destination operand.

The operand size is always 32 bits if not in Long Mode. In other words, XOP.W1 is treated as XOP.W0 outside Long Mode.

Operation

public void BLSFILL(ref U32 dest, U32 src)
{
    dest = src | (src - 1);
}

public void BLSFILL(ref U64 dest, U64 src)
{
    dest = src | (src - 1);
}

Flags Affected

CF (carry flag)

Set according to the result.

PF (parity flag)

Set according to the result.

AF (auxiliary flag)

Set according to the result.

ZF (zero flag)

Set according to the result.

SF (sign flag)

Set according to the result.

OF (overflow flag)

Set according to the result.

Intrinsics

Exceptions

SIMD Floating-Point

Other Exceptions