CNT

Count bits

This instruction counts the number of binary one bits in the value of the source register, and writes the result to the destination register.

Integer class

(FEAT_CSSC)

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
sf	1	0	1	1	0	1	0	1	1	0	0	0	0	0	0	0	0	0	1	1	1	Rn					Rd
		S									opcode2					opcode

32-bit encoding

(sf == 0)

CNT <Wd>, <Wn>

64-bit encoding

(sf == 1)

CNT <Xd>, <Xn>

Decode (all encodings)

if !IsFeatureImplemented(FEAT_CSSC) then EndOfDecode(Decode_UNDEF); constant integer datasize = 32 << UInt(sf); constant integer d = UInt(Rd); constant integer n = UInt(Rn);

Assembler Symbols

<Wd>	Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field.

<Wn>	Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field.

<Xd>	Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.

<Xn>	Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field.

Operation

constant bits(datasize) operand1 = X[n, datasize]; constant integer result = BitCount(operand1); X[d, datasize] = result<datasize-1:0>;

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.

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CNT