# VFCMADDCSH/VFMADDCSH — Complex Multiply and Accumulate Scalar FP16 Values

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.MAP6.W0 57 /r VFCMADDCSH xmm1{k1}{z}, xmm2, xmm3/m32 {er} | A | V/V | AVX512-FP16 | Complex multiply a pair of FP16 values from xmm2 and complex conjugate of xmm3/m32, add to xmm1 and store the result in xmm1 subject to writemask k1. Bits 127:32 of xmm2 are copied to xmm1[127:32].
EVEX.LLIG.F3.MAP6.W0 57 /r VFMADDCSH xmm1{k1}{z}, xmm2, xmm3/m32 {er} | A | V/V | AVX512-FP16 | Complex multiply a pair of FP16 values from xmm2 and xmm3/m32, add to xmm1 and store the result in xmm1 subject to writemask k1. Bits 127:32 of xmm2 are copied to xmm1[127:32].

## Instruction Operand Encoding ¶

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

### Description ¶

This instruction performs a complex multiply and accumulate operation. There are normal and complex conjugate forms of the operation.

The masking for this operation is done on 32-bit quantities representing a pair of FP16 values.

Bits 127:32 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.

Rounding is performed at every FMA (fused multiply and add) boundary. Execution occurs as if all MXCSR exceptions are masked. MXCSR status bits are updated to reflect exceptional conditions.

### Operation ¶

#### VFCMADDCSH dest{k1}, src1, src2 (AVX512) ¶

    IF k1[0] or *no writemask*:
        tmp[0] := dest.fp16[0] + src1.fp16[0] * src2.fp16[0]
        tmp[1] := dest.fp16[1] + src1.fp16[1] * src2.fp16[0]
        // conjugate version subtracts odd final term
        dest.fp16[0] := tmp[0] + src1.fp16[1] * src2.fp16[1]
        dest.fp16[1] := tmp[1] - src1.fp16[0] * src2.fp16[1]
    ELSE IF *zeroing*:
        dest.fp16[0] := 0
        dest.fp16[1] := 0
    DEST[127:32] := src1[127:32] // copy upper part of src1
    DEST[MAXVL-1:128] := 0

#### VFMADDCSH dest{k1}, src1, src2 (AVX512) ¶

    IF k1[0] or *no writemask*:
        tmp[0] := dest.fp16[0] + src1.fp16[0] * src2.fp16[0]
        tmp[1] := dest.fp16[1] + src1.fp16[1] * src2.fp16[0]
        // non-conjugate version subtracts last even term
        dest.fp16[0] := tmp[0] - src1.fp16[1] * src2.fp16[1]
        dest.fp16[1] := tmp[1] + src1.fp16[0] * src2.fp16[1]
    ELSE IF *zeroing*:
        dest.fp16[0] := 0
        dest.fp16[1] := 0
    DEST[127:32] := src1[127:32] // copy upper part of src1
    DEST[MAXVL-1:128] := 0

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

    VFCMADDCSH __m128h _mm_fcmadd_round_sch (__m128h a, __m128h b, __m128h c, const int rounding);

    VFCMADDCSH __m128h _mm_mask_fcmadd_round_sch (__m128h a, __mmask8 k, __m128h b, __m128h c, const int rounding);

    VFCMADDCSH __m128h _mm_mask3_fcmadd_round_sch (__m128h a, __m128h b, __m128h c, __mmask8 k, const int rounding);

    VFCMADDCSH __m128h _mm_maskz_fcmadd_round_sch (__mmask8 k, __m128h a, __m128h b, __m128h c, const int rounding);

    VFCMADDCSH __m128h _mm_fcmadd_sch (__m128h a, __m128h b, __m128h c);

    VFCMADDCSH __m128h _mm_mask_fcmadd_sch (__m128h a, __mmask8 k, __m128h b, __m128h c);

    VFCMADDCSH __m128h _mm_mask3_fcmadd_sch (__m128h a, __m128h b, __m128h c, __mmask8 k);

    VFCMADDCSH __m128h _mm_maskz_fcmadd_sch (__mmask8 k, __m128h a, __m128h b, __m128h c);

    VFMADDCSH __m128h _mm_fmadd_round_sch (__m128h a, __m128h b, __m128h c, const int rounding);

    VFMADDCSH __m128h _mm_mask_fmadd_round_sch (__m128h a, __mmask8 k, __m128h b, __m128h c, const int rounding);

    VFMADDCSH __m128h _mm_mask3_fmadd_round_sch (__m128h a, __m128h b, __m128h c, __mmask8 k, const int rounding);

    VFMADDCSH __m128h _mm_maskz_fmadd_round_sch (__mmask8 k, __m128h a, __m128h b, __m128h c, const int rounding);

    VFMADDCSH __m128h _mm_fmadd_sch (__m128h a, __m128h b, __m128h c);

    VFMADDCSH __m128h _mm_mask_fmadd_sch (__m128h a, __mmask8 k, __m128h b, __m128h c);

    VFMADDCSH __m128h _mm_mask3_fmadd_sch (__m128h a, __m128h b, __m128h c, __mmask8 k);

    VFMADDCSH __m128h _mm_maskz_fmadd_sch (__mmask8 k, __m128h a, __m128h b, __m128h c);

### SIMD Floating-Point Exceptions ¶

Invalid, Underflow, Overflow, Precision, Denormal.

### Other Exceptions ¶

EVEX-encoded instructions, see Table 2-58, “Type E10 Class Exception Conditions.”

Additionally:

#UD | If (dest_reg == src1_reg) or (dest_reg == src2_reg).