# VCVTSD2SH — Convert Low FP64 Value to an FP16 Value

Instruction En Bit Mode Flag Support Instruction En Bit Mode Flag Support 64/32 CPUID Feature Instruction En Bit Mode Flag CPUID Feature Instruction En Bit Mode Flag Op/ 64/32 CPUID Feature Instruction En Bit Mode Flag 64/32 CPUID Feature Instruction En Bit Mode Flag CPUID Feature Instruction En Bit Mode Flag Op/ 64/32 CPUID Feature |  | Support |  | Description
--- | --- | --- | --- | ---
EVEX.LLIG.F2.MAP5.W1 5A /r VCVTSD2SH xmm1{k1}{z}, xmm2, xmm3/m64 {er} | A | V/V | AVX512-FP16 | Convert the low FP64 value in xmm3/m64 to an FP16 value and store the result in the low element of xmm1 subject to writemask k1. Bits 127:16 of xmm2 are copied to xmm1[127:16].

## Instruction Operand Encoding ¶

Op/En | Tuple | Operand 1 | Operand 2 | Operand 3 | Operand 4
--- | --- | --- | --- | --- | ---
A | Scalar | ModRM:reg (w) | VEX.vvvv (r) | ModRM:r/m (r) | N/A

### Description ¶

This instruction converts the low FP64 value in the second source operand to an FP16 value, and stores the result in the low element of the destination operand.

When the conversion is inexact, the value returned is rounded according to the rounding control bits in the MXCSR register.

Bits 127:16 of the destination operand are copied from the corresponding bits of the first source operand. Bits MAXVL-1:128 of the destination operand are zeroed. The low FP16 element of the destination is updated according to the writemask.

### Operation ¶

#### VCVTSD2SH dest, src1, src2 ¶

    IF *SRC2 is a register* and (EVEX.b = 1):
        SET_RM(EVEX.RC)
    ELSE:
        SET_RM(MXCSR.RC)
    IF k1[0] OR *no writemask*:
        DEST.fp16[0] := Convert_fp64_to_fp16(SRC2.fp64[0])
    ELSE IF *zeroing*:
        DEST.fp16[0] := 0
    // else dest.fp16[0] remains unchanged
    DEST[127:16] := SRC1[127:16]
    DEST[MAXVL-1:128] := 0

### Intel C/C++ Compiler Intrinsic Equivalent ¶

    VCVTSD2SH __m128h _mm_cvt_roundsd_sh (__m128h a, __m128d b, const int rounding);

    VCVTSD2SH __m128h _mm_mask_cvt_roundsd_sh (__m128h src, __mmask8 k, __m128h a, __m128d b, const int rounding);

    VCVTSD2SH __m128h _mm_maskz_cvt_roundsd_sh (__mmask8 k, __m128h a, __m128d b, const int rounding);

    VCVTSD2SH __m128h _mm_cvtsd_sh (__m128h a, __m128d b);

    VCVTSD2SH __m128h _mm_mask_cvtsd_sh (__m128h src, __mmask8 k, __m128h a, __m128d b);

    VCVTSD2SH __m128h _mm_maskz_cvtsd_sh (__mmask8 k, __m128h a, __m128d b);

### SIMD Floating-Point Exceptions ¶

Invalid, Underflow, Overflow, Precision, Denormal.

### Other Exceptions ¶

EVEX-encoded instructions, see Table 2-47, “Type E3 Class Exception Conditions.”