Variable Blend Packed Single-Precision Floating-Point Values

Encoding

EncodingOperand 1Operand 2Operand 3Operand 4
rmModRM.reg[rw]ModRM.r/m[r]XMM0
rvmbModRM.reg[w]VEX.vvvv[r]ModRM.r/m[r]imm8(4..7)

Description

The (V)BLENDVPS instruction conditionally moves single-precision floating-point values from the two source operands. From the control operand, each bit, if cleared, will move from the first source operand, and, if set, will move from the second source operand. The result is stored in the destination operand.

This instruction, despite being named as if it operates on floating-point numbers, will work on 64 bit integers as well.

All forms except the legacy SSE one will zero the upper (untouched) bits.

Operation

public void BLENDVPS(SimdF32 dest, SimdF32 src)
{
    // if `XMM0.Bit[n]` is 0, `dest` will be copied into itself (i.e. nothing happens)
    if (XMM0.Bit[0])
        dest[0] = src[0];
    if (XMM0.Bit[1])
        dest[1] = src[1];
    if (XMM0.Bit[2])
        dest[2] = src[2];
    if (XMM0.Bit[3])
        dest[3] = src[3];
    // dest[4..] is unmodified
}

void VBLENDVPS_Vex(SimdF32 dest, SimdF32 src1, SimdF32 src2, SimdF32 mask, int kl)
{
    for (int n = 0; n < kl; n++)
        dest[n] = mask.Bit[n] ? src2[n] : src1[n];
    dest[kl..] = 0;
}
public void VBLENDVPS_Vex128(SimdF32 dest, SimdF32 src1, SimdF32 src2, SimdF32 mask) =>
    VBLENDVPS_Vex(dest, src1, src2, mask, 4);
public void VBLENDVPS_Vex256(SimdF32 dest, SimdF32 src1, SimdF32 src2, SimdF32 mask) =>
    VBLENDVPS_Vex(dest, src1, src2, mask, 8);

Intrinsics

Exceptions

SIMD Floating-Point

None.

Other Exceptions

VEX Encoded Form: See Type 4 Exception Conditions.

#UD
  • If VEX.W is not 0.