CNTP (predicate as counter)
Set scalar to count from predicate-as-counter
Counts the number of true elements in the source predicate and places the scalar result in the destination general-purpose register.
Green
False
0
0
1
0
0
1
0
1
1
0
0
0
0
0
1
0
0
0
0
1
CNTP <Xd>, <PNn>.<T>, <vl>
if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then UNDEFINED;
constant integer esize = 8 << UInt(size);
constant integer n = UInt(PNn);
constant integer d = UInt(Rd);
constant integer width = 2 << UInt(vl);
<Xd>
Is the 64-bit name of the destination general-purpose register, encoded in the "Rd" field.
<PNn>
Is the name of the first source scalable predicate register, with predicate-as-counter encoding, encoded in the "PNn" field.
<T>
Is the size specifier,
size
<T>
00
B
01
H
10
S
11
D
<vl>
Is the vl specifier,
if IsFeatureImplemented(FEAT_SVE2p1) then CheckSVEEnabled(); else CheckStreamingSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
constant bits(PL) pred = P[n, PL];
constant bits(PL*4) mask = CounterToPredicate(pred<15:0>, PL*4);
bits(64) sum = Zeros(64);
constant integer limit = elements * width;
for e = 0 to limit-1
if ActivePredicateElement(mask, e, esize) then
sum = sum + 1;
X[d, 64] = sum;