CSEL -- A64

This instruction writes the value of the first source register to the destination register if the condition is TRUE. If the condition is FALSE, it writes the value of the second source register to the destination register.

Decode for all variants of this encoding

let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm); let datasize : integer{} = 32 << UInt(sf); let condition : bits(4) = cond;

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 first general-purpose source register, encoded in the "Rn" field.

<Wm>	Is the 32-bit name of the second general-purpose source register, encoded in the "Rm" field.

<cond>

Is one of the standard conditions, encoded in the standard way, and encoded in cond:

cond	<cond>
0000	EQ
0001	NE
0010	CS
0011	CC
0100	MI
0101	PL
0110	VS
0111	VC
1000	HI
1001	LS
1010	GE
1011	LT
1100	GT
1101	LE
1110	AL
1111	NV

<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 first general-purpose source register, encoded in the "Rn" field.

<Xm>	Is the 64-bit name of the second general-purpose source register, encoded in the "Rm" field.

Operation

var result : bits(datasize); if ConditionHolds(condition) then result = X{datasize}(n); else result = X{datasize}(m); end; X{datasize}(d) = result;

Operational information

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

2026-03_rel 2026-03-26 20:48:11

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	0	0	1	1	0	1	0	1	0	0	Rm					cond				0	0	Rn					Rd
	op	S																			o2

CSEL

Encoding for the 32-bit variant

Encoding for the 64-bit variant

Decode for all variants of this encoding

Assembler Symbols

Operation

Operational information