UUNPK

Unpack and zero-extend multi-vector elements

This instruction unpacks elements from one or two source vectors and then zero-extends them to place in elements of twice their size within the two or four destination vectors.

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	0	1	0	1	1	1	1	0	0	0										1
								size														Zn					Zd				U

UUNPK { <Zd1>.<T>-<Zd2>.<T> }, <Zn>.<Tb>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer n = UInt(Zn);
constant integer d = UInt(Zd:'0');
constant integer nreg = 2;
constant boolean unsigned = TRUE;

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	1	0	1	0	1	1	1	1	0	0	0					0				0	1
								size														Zn					Zd				U

UUNPK { <Zd1>.<T>-<Zd4>.<T> }, { <Zn1>.<Tb>-<Zn2>.<Tb> }

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
if size == '00' then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer n = UInt(Zn:'0');
constant integer d = UInt(Zd:'00');
constant integer nreg = 4;
constant boolean unsigned = TRUE;

Operation

CheckStreamingSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
constant integer hsize = esize DIV 2;
constant integer sreg = nreg DIV 2;
array [0..3] of bits(VL) results;

for r = 0 to sreg-1
    constant bits(VL) operand = Z[n+r, VL];
    for i = 0 to 1
        for e = 0 to elements-1
            constant bits(hsize) element = Elem[operand, i*elements + e, hsize];
            Elem[results[2*r+i], e, esize] = Extend(element, esize, unsigned);

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

Explanations

<Zd1>: For the "Two registers" variant: is the name of the first scalable vector register of the destination multi-vector group, encoded as "Zd" times 2.
<Zd1>: For the "Four registers" variant: is the name of the first scalable vector register of the destination multi-vector group, encoded as "Zd" times 4.
<T>: <Zd2>: Is the name of the second scalable vector register of the destination multi-vector group, encoded as "Zd" times 2 plus 1.
<Zn>: Is the name of the source scalable vector register, encoded in the "Zn" field.
<Tb>: <Zd4>: Is the name of the fourth scalable vector register of the destination multi-vector group, encoded as "Zd" times 4 plus 3.
<Zn1>: Is the name of the first scalable vector register of the source multi-vector group, encoded as "Zn" times 2.
<Zn2>: Is the name of the second scalable vector register of the source multi-vector group, encoded as "Zn" times 2 plus 1.

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.