VGETMANTPD—Extract Float64 Vector of Normalized Mantissas from Float64 Vector

Instruction Operand Encoding

Description

Convert double-precision floating values in the source operand (the second operand) to DP FP values with the mantissa normalization and sign control specified by the imm8 byte. The converted results are written to the destination operand (the first operand) using writemask k1. The normalized mantissa is specified by interv (imm8[1:0]) and the sign control (sc) is specified by bits 3:2 of the immediate byte.

The destination operand is a ZMM/YMM/XMM register updated under the writemask. The source operand can be a ZMM/YMM/XMM register, a 512/256/128-bit memory location, or a 512/256/128-bit vector broadcasted from a 64-bit memory location.

For each input DP FP value x, The conversion operation is:

GetMant(x) = ±2^k|x.significand|

where: 1 <= |x.significand| < 2

Unbiased exponent k depends on the interval range defined by interv and whether the exponent of the source is even or odd. The sign of the final result is determined by sc and the source sign.

If interv != 0 then k = -1, otherwise K = 0. The encoded value of imm8[1:0] and sign control are shown in

Each converted DP FP result is encoded according to the sign control, the unbiased exponent k (adding bias) and a mantissa normalized to the range specified by interv.

The GetMant() function follows Table 5-9 when dealing with floating-point special numbers.

This instruction is writemasked, so only those elements with the corresponding bit set in vector mask register k1 are computed and stored into the destination. Elements in zmm1 with the corresponding bit clear in k1 retain their previous values.

Note: EVEX.vvvv is reserved and must be 1111b; otherwise instructions will #UD.

Table 5-9. GetMant() Special Float Values Behavior

Operation

GetNormalizeMantissaDP(SRC[63:0], SignCtrl[1:0], Interv[1:0])
{
// Extracting the SRC sign, exponent and mantissa fields
Dst.sign (cid:197) SignCtrl[0] ? 0 : Src[63];
// Get sign bit
Dst.exp (cid:197) SRC[62:52];
; Get original exponent value
Dst.fraction (cid:197) SRC[51:0];; Get original fraction value
ZeroOperand (cid:197) (Dst.exp = 0) AND (Dst.fraction = 0);
DenormOperand (cid:197) (Dst.exp = 0h) AND (Dst.fraction != 0);
InfiniteOperand (cid:197) (Dst.exp = 07FFh) AND (Dst.fraction = 0);
NaNOperand (cid:197) (Dst.exp = 07FFh) AND (Dst.fraction != 0);
// Check for NAN operand
IF (NaNOperand)
    {
    IF (SRC = SNaN) {Set #IE;}
        Return QNAN(SRC);
        }
        // Check for Zero and Infinite operands
        IF ((ZeroOperand) OR (InfiniteOperand)
            {
            Dst.exp (cid:197) 03FFh;
            // Override exponent with BIAS
            Return ((Dst.sign<<63) | (Dst.exp<<52) | (Dst.fraction));
            }
            // Check for negative operand (including -0.0)
            IF ((Src[63] = 1) AND SignCtrl[1])
                {
                Set #IE;
                Return QNaN_Indefinite;
                }
                // Checking for denormal operands
                IF (DenormOperand)
                    {
                    IF (MXCSR.DAZ=1) Dst.fraction (cid:197) 0;// Zero out fraction
                        ELSE
                        {
                        // Jbit is the hidden integral bit. Zero in case of denormal operand.
                        Src.Jbit (cid:197) 0;
                        // Zero Src Jbit
                        Dst.exp (cid:197) 03FFh;
                        // Override exponent with BIAS
                        WHILE (Src.Jbit = 0) {
                        // normalize mantissa
                        Src.Jbit (cid:197) Dst.fraction[51];
                        // Get the fraction MSB
                        Dst.fraction (cid:197) (Dst.fraction << 1);
                        // Start normalizing the mantissa
                        Dst.exp-- ;
                        // Adjust the exponent
                        }
                        SET #DE;
                        // Set DE bit
                        }
                        }
                        // At this point, Dst.fraction is normalized.
                        // Checking for exponent response
                        Unbiased.exp (cid:197) Dst.exp – 03FFh;
                        // subtract the bias from exponent
                        IsOddExp (cid:197) Unbiased.exp[0];
                        // recognized unbiased ODD exponent
                        SignalingBit (cid:197) Dst.fraction[51];
                        CASE (interv[1:0])
                        00: Dst.exp (cid:197) 03FFh;
                        // This is the bias
                        01: Dst.exp (cid:197) (IsOddExp) ? 03FEh : 03FFh;
                        // either bias-1, or bias
                        10: Dst.exp (cid:197) 03FEh;
                        // bias-1
                        11: Dst.exp (cid:197) (SignalingBit) ? 03FEh : 03FFh;
                        // either bias-1, or bias
                        ESCA
                        // At this point Dst.exp has the correct result. Form the final destination
                        DEST[63:0] (cid:197) (Dst.sign << 63) OR (Dst.exp << 52) OR (Dst.fraction);
                        Return (DEST);
                        }
                        SignCtrl[1:0] (cid:197) IMM8[3:2];
                        Interv[1:0] (cid:197) IMM8[1:0];

(KL, VL) = (2, 128), (4, 256), (8, 512)
FOR j (cid:197) 0 TO KL-1
    i (cid:197) j * 64
    IF k1[j] OR *no writemask*
        THEN
        IF (EVEX.b = 1) AND (SRC *is memory*)
            THEN
            DEST[i+63:i] (cid:197)(cid:3)GetNormalizedMantissaDP(SRC[63:0], sc, interv)
            ELSE
            DEST[i+63:i] (cid:197)(cid:3)GetNormalizedMantissaDP(SRC[i+63:i], sc, interv)
        FI;
        ELSE
        IF *merging-masking*
            ; merging-masking
            THEN *DEST[i+63:i] remains unchanged*
            ELSE
            ; zeroing-masking
            DEST[i+63:i] (cid:197) 0
        FI
    FI;
ENDFOR
DEST[MAX_VL-1:VL] (cid:197) 0

Intel C/C++ Compiler Intrinsic Equivalent

VGETMANTPD __m512d _mm512_getmant_pd( __m512d a, enum intv, enum sgn);
VGETMANTPD __m512d _mm512_mask_getmant_pd(__m512d s, __mmask8 k, __m512d a, enum intv, enum sgn);
VGETMANTPD __m512d _mm512_maskz_getmant_pd( __mmask8 k, __m512d a, enum intv, enum sgn);
VGETMANTPD __m512d _mm512_getmant_round_pd( __m512d a, enum intv, enum sgn, int r);
VGETMANTPD __m512d _mm512_mask_getmant_round_pd(__m512d s, __mmask8 k, __m512d a, enum intv, enum sgn, int r);
VGETMANTPD __m512d _mm512_maskz_getmant_round_pd( __mmask8 k, __m512d a, enum intv, enum sgn, int r);
VGETMANTPD __m256d _mm256_getmant_pd( __m256d a, enum intv, enum sgn);
VGETMANTPD __m256d _mm256_mask_getmant_pd(__m256d s, __mmask8 k, __m256d a, enum intv, enum sgn);
VGETMANTPD __m256d _mm256_maskz_getmant_pd( __mmask8 k, __m256d a, enum intv, enum sgn);
VGETMANTPD __m128d _mm_getmant_pd( __m128d a, enum intv, enum sgn);
VGETMANTPD __m128d _mm_mask_getmant_pd(__m128d s, __mmask8 k, __m128d a, enum intv, enum sgn);
VGETMANTPD __m128d _mm_maskz_getmant_pd( __mmask8 k, __m128d a, enum intv, enum sgn);

SIMD Floating-Point Exceptions

Denormal, Invalid

Other Exceptions

See Exceptions Type E2.