SQDMULH (multiple and single vector)

Multi-vector signed saturating doubling multiply high by vector

This instruction multiplies then doubles the corresponding signed elements of the two or four first source vectors and the signed elements of the second source vector, and destructively places the most significant half of the result in the corresponding elements of the two or four first source vectors. Each result element is saturated to the N-bit element's signed integer range -2(N-1) to (2(N-1))-1.

This instruction is unpredicated.

Encoding: Two registers

Variants: FEAT_SME2 (ARMv9.3)

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
1	1	0	0	0	0	0	1			1	0					1	0	1	0	0	1	0	0	0	0	0					0
								size				Zm															Zdn				op

SQDMULH { <Zdn1>.<T>-<Zdn2>.<T> }, { <Zdn1>.<T>-<Zdn2>.<T> }, <Zm>.<T>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer dn = UInt(Zdn:'0');
constant integer m = UInt('0':Zm);
constant integer nreg = 2;

Encoding: Four registers

Variants: FEAT_SME2 (ARMv9.3)

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
1	1	0	0	0	0	0	1			1	0					1	0	1	0	1	1	0	0	0	0	0				0	0
								size				Zm															Zdn				op

SQDMULH { <Zdn1>.<T>-<Zdn4>.<T> }, { <Zdn1>.<T>-<Zdn4>.<T> }, <Zm>.<T>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer dn = UInt(Zdn:'00');
constant integer m = UInt('0':Zm);
constant integer nreg = 4;

Operation

CheckStreamingSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
array [0..3] of bits(VL) results;

for r = 0 to nreg-1
    constant bits(VL) operand1 = Z[dn+r, VL];
    constant bits(VL) operand2 = Z[m, VL];
    for e = 0 to elements-1
        constant integer element1 = SInt(Elem[operand1, e, esize]);
        constant integer element2 = SInt(Elem[operand2, e, esize]);
        constant integer res = 2 * element1 * element2;
        Elem[results[r], e, esize] = SignedSat(res >> esize, esize);

for r = 0 to nreg-1
    Z[dn+r, VL] = results[r];

Explanations

<Zdn1>: For the "Two registers" variant: is the name of the first scalable vector register of the destination and first source multi-vector group, encoded as "Zdn" times 2.
<Zdn1>: For the "Four registers" variant: is the name of the first scalable vector register of the destination and first source multi-vector group, encoded as "Zdn" times 4.
<T>: <Zdn2>: Is the name of the second scalable vector register of the destination and first source multi-vector group, encoded as "Zdn" times 2 plus 1.
<Zm>: Is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field.
<Zdn4>: Is the name of the fourth scalable vector register of the destination and first source multi-vector group, encoded as "Zdn" times 4 plus 3.

Operational Notes

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.