FMUL (indexed)

Floating-point multiply by indexed elements

Multiply all floating-point elements within each 128-bit segment of the first source vector by the specified element in the corresponding second source vector segment. The results are placed in the corresponding elements of the destination vector.

The elements within the second source vector are specified using an immediate index which selects the same element position within each 128-bit vector segment. The index range is from 0 to one less than the number of elements per 128-bit segment. This instruction is unpredicated.

Encoding: Half-precision

Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	0	0		1						0	0	1	0	0	0
									i3h		i3l		Zm							o2		Zn					Zd

FMUL <Zd>.H, <Zn>.H, <Zm>.H[<imm>]

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 16;
constant integer index = UInt(i3h:i3l);
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer d = UInt(Zd);

Encoding: Single-precision

Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	0	1	0	1						0	0	1	0	0	0
								size			i2		Zm							o2		Zn					Zd

FMUL <Zd>.S, <Zn>.S, <Zm>.S[<imm>]

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 32;
constant integer index = UInt(i2);
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer d = UInt(Zd);

Encoding: Double-precision

Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	0	1	1	1						0	0	1	0	0	0
								size			i1	Zm								o2		Zn					Zd

FMUL <Zd>.D, <Zn>.D, <Zm>.D[<imm>]

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 64;
constant integer index = UInt(i1);
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer d = UInt(Zd);

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
constant integer eltspersegment = 128 DIV esize;
constant bits(VL) op1 = Z[n, VL];
constant bits(VL) op2 = Z[m, VL];
bits(VL) result;

for e = 0 to elements-1
    constant integer segmentbase = e - (e MOD eltspersegment);
    constant integer s = segmentbase + index;
    constant bits(esize) elem2 = Elem[op2, s, esize];
    constant bits(esize) elem1 = Elem[op1, e, esize];
    Elem[result, e, esize] = FPMul(elem1, elem2, FPCR);

Z[d, VL] = result;

Explanations

<Zd>: Is the name of the destination scalable vector register, encoded in the "Zd" field.
<Zn>: Is the name of the first source scalable vector register, encoded in the "Zn" field.
<Zm>: For the "Half-precision" and "Single-precision" variants: is the name of the second source scalable vector register Z0-Z7, encoded in the "Zm" field.
<Zm>: For the "Double-precision" variant: is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field.
<imm>: For the "Half-precision" variant: is the immediate index, in the range 0 to 7, encoded in the "i3h:i3l" fields.
<imm>: For the "Single-precision" variant: is the immediate index, in the range 0 to 3, encoded in the "i2" field.
<imm>: For the "Double-precision" variant: is the immediate index, in the range 0 to 1, encoded in the "i1" field.