SQCVT (four registers)

Multi-vector signed saturating extract narrow

This instruction saturates the signed integer value in each element of the four source vectors to quarter the original source element width, and places the results in the quarter-width destination elements.

This instruction is unpredicated.

Encoding: SME2

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		0	1	1	0	0	1	1	1	1	1	0	0	0				0	0
								sz	op													Zn			N	U	Zd

SQCVT <Zd>.<T>, { <Zn1>.<Tb>-<Zn4>.<Tb> }

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(sz);
constant integer n = UInt(Zn:'00');
constant integer d = UInt(Zd);

Operation

CheckStreamingSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV (4 * esize);
bits(VL) result;

for r = 0 to 3
    constant bits(VL) operand = Z[n+r, VL];
    for e = 0 to elements-1
        constant integer element = SInt(Elem[operand, e, 4 * esize]);
        Elem[result, r*elements + e, esize] = SignedSat(element, esize);

Z[d, VL] = result;

Explanations

<Zd>: Is the name of the destination scalable vector register, encoded in the "Zd" field.
<T>: <Zn1>: Is the name of the first scalable vector register of the source multi-vector group, encoded as "Zn" times 4.
<Tb>: <Zn4>: Is the name of the fourth scalable vector register of the source multi-vector group, encoded as "Zn" times 4 plus 3.