BRKA

Break after first true condition

Sets destination predicate elements up to and including the first active and true source element to true, then sets subsequent elements to false.

Inactive elements in the destination predicate register remain unmodified or are set to zero, depending on whether merging or zeroing predication is selected. Does not set the condition flags.

Encoding: Not setting the condition flags

Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

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
0	0	1	0	0	1	0	1	0	0	0	1	0	0	0	0	0	1					0
								B	S									Pg					Pn				M	Pd

BRKA <Pd>.B, <Pg>/<ZM>, <Pn>.B

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 8;
constant integer g = UInt(Pg);
constant integer n = UInt(Pn);
constant integer d = UInt(Pd);
constant boolean merging = (M == '1');
constant boolean setflags = FALSE;

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
constant bits(PL) mask = P[g, PL];
constant bits(PL) operand = P[n, PL];
constant bits(PL) operand2 = if merging then P[d, PL] else Zeros(PL);
boolean break = FALSE;
bits(PL) result;
constant integer psize = esize DIV 8;

for e = 0 to elements-1
    constant boolean element = ActivePredicateElement(operand, e, esize);
    if ActivePredicateElement(mask, e, esize) then
        constant bit pbit = if !break then '1' else '0';
        Elem[result, e, psize] = ZeroExtend(pbit, psize);
        break = break || element;
    elsif merging then
        constant bit pbit = PredicateElement(operand2, e, esize);
        Elem[result, e, psize] = ZeroExtend(pbit, psize);
    else
        Elem[result, e, psize] = ZeroExtend('0', psize);

if setflags then
    PSTATE. = PredTest(mask, result, esize);
P[d, PL] = result;

Explanations

<Pd>: Is the name of the destination scalable predicate register, encoded in the "Pd" field.
<Pg>: Is the name of the governing scalable predicate register, encoded in the "Pg" field.
<ZM>: <Pn>: Is the name of the source scalable predicate register, encoded in the "Pn" field.