LUTI4 (two registers)
Lookup table read with 4-bit indexes
Copy 8-bit, 16-bit or 32-bit elements from ZT0 to two destination vectors using packed 4-bit indices from a segment of the source vector register. A segment corresponds to a portion of the source vector that is consumed in order to fill the destination vector. The segment is selected by the vector segment index modulo the total number of segments.
This instruction is unpredicated.
S1: Green, S2: Amber
False
SM_1_only
It has encodings from 2 classes:
Consecutive
and
Strided
1
1
0
0
0
0
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1
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0
0
0
LUTI4 { <Zd1>.<T>-<Zd2>.<T> }, ZT0, <Zn>[<index>]
if !HaveSME2() then UNDEFINED;
if size == '11' then UNDEFINED;
constant integer esize = 8 << UInt(size);
integer isize = 4;
integer n = UInt(Zn);
integer dstride = 1;
integer d = UInt(Zd:'0');
integer imm = UInt(i2);
constant integer nreg = 2;
1
1
0
0
0
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0
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LUTI4 { <Zd1>.<T>, <Zd2>.<T> }, ZT0, <Zn>[<index>]
if !HaveSME2p1() then UNDEFINED;
if size == '10' || size == '11' then UNDEFINED;
constant integer esize = 8 << UInt(size);
integer isize = 4;
integer n = UInt(Zn);
integer dstride = 8;
integer d = UInt(D:'0':Zd);
integer imm = UInt(i2);
constant integer nreg = 2;
<Zd1>
For the consecutive variant: is the name of the first destination scalable vector register of a multi-vector sequence, encoded as "Zd" times 2.
<Zd1>
For the strided variant: is the name of the first destination scalable vector register Z0-Z7 or Z16-Z23 of a multi-vector sequence, encoded as "D:'0':Zd".
<T>
For the consecutive variant: is the size specifier,
size
<T>
00
B
01
H
10
S
11
RESERVED
<T>
For the strided variant: is the size specifier,
<Zd2>
For the consecutive variant: is the name of the second destination scalable vector register of a multi-vector sequence, encoded as "Zd" times 2 plus 1.
<Zd2>
For the strided variant: is the name of the second destination scalable vector register Z8-Z15 or Z24-Z31 of a multi-vector sequence, encoded as "D:'1':Zd".
<Zn>
Is the name of the source scalable vector register, encoded in the "Zn" field.
<index>
Is the vector segment index, in the range 0 to 3, encoded in the "i2" field.
CheckStreamingSVEEnabled();
CheckSMEZT0Enabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
integer segments = esize DIV (isize * nreg);
integer segment = imm MOD segments;
bits(VL) indexes = Z[n, VL];
bits(512) table = ZT0[512];
for r = 0 to nreg-1
integer base = (segment * nreg + r) * elements;
bits(VL) result = Z[d, VL];
for e = 0 to elements-1
integer index = UInt(Elem[indexes, base+e, isize]);
Elem[result, e, esize] = Elem[table, index, 32]<esize-1:0>;
Z[d, VL] = result;
d = d + dstride;