_mm_reduce_round_sd
Classification
AVX-512, Miscellaneous, CPUID Test: AVX512DQ
Header File
immintrin.h
Instruction
VREDUCESD xmm, xmm, xmm {sae}, imm8
Synopsis
 _mm_reduce_round_sd(__m128d a, __m128d b, int imm8, int sae);
Description
Extract the reduced argument of the lower double-precision (64-bit) floating-point element in "b" by the number of bits specified by "imm8", store the result in the lower element of "dst", and copy the upper element from "a" to the upper element of "dst". [round_imm_note][sae_note]
Operation
DEFINE ReduceArgumentPD(src1[63:0], imm8[7:0]) {
	m[63:0] := FP64(imm8[7:4]) // number of fraction bits after the binary point to be preserved
	tmp[63:0] := POW(2.0, -m) * ROUND(POW(2.0, m) * src1[63:0], imm8[3:0])
	tmp[63:0] := src1[63:0] - tmp[63:0]
	IF IsInf(tmp[63:0])
		tmp[63:0] := FP64(0.0)
	FI
	RETURN tmp[63:0]
}
dst[63:0] := ReduceArgumentPD(b[63:0], imm8[7:0])
dst[127:64] := a[127:64]
dst[MAX:128] := 0