CSEL
Conditional select
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.
If PSTATE.DIT is 1:
The execution time of this instruction is independent of:
The values of the data supplied in any of its registers.
The values of the NZCV flags.
The response of this instruction to asynchronous exceptions does not vary based on:
The values of the data supplied in any of its registers.
The values of the NZCV flags.
0
0
1
1
0
1
0
1
0
0
0
0
0
CSEL <Wd>, <Wn>, <Wm>, <cond>
1
CSEL <Xd>, <Xn>, <Xm>, <cond>
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
constant integer datasize = 32 << UInt(sf);
constant bits(4) condition = cond;
<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
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.
bits(datasize) result;
if ConditionHolds(condition) then
result = X[n, datasize];
else
result = X[m, datasize];
X[d, datasize] = result;