UMAXV
Unsigned maximum across vector
This instruction compares all the
vector elements in the source SIMD&FP register,
and writes the largest of the values
as a scalar to the destination SIMD&FP register.
All the values in this instruction are unsigned integer values.
Depending on the settings in the CPACR_EL1,
CPTR_EL2, and CPTR_EL3 registers,
and the current Security state and Exception level,
an attempt to execute the instruction might be trapped.
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
1
0
1
1
1
0
1
1
0
0
0
0
1
0
1
0
1
0
UMAXV <V><d>, <Vn>.<T>
if size:Q == '100' then UNDEFINED;
if size == '11' then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer esize = 8 << UInt(size);
constant integer datasize = 64 << UInt(Q);
constant integer elements = datasize DIV esize;
constant boolean unsigned = TRUE;
<V>
Is the destination width specifier,
size
<V>
00
B
01
H
10
S
11
RESERVED
<d>
Is the number of the SIMD&FP destination register, encoded in the "Rd" field.
<Vn>
Is the name of the SIMD&FP source register, encoded in the "Rn" field.
<T>
Is an arrangement specifier,
size
Q
<T>
00
0
8B
00
1
16B
01
0
4H
01
1
8H
10
0
RESERVED
10
1
4S
11
x
RESERVED
CheckFPAdvSIMDEnabled64();
constant bits(datasize) operand = V[n, datasize];
integer max = Int(Elem[operand, 0, esize], unsigned);
for e = 1 to elements-1
constant integer element = Int(Elem[operand, e, esize], unsigned);
max = Max(max, element);
V[d, esize] = max<esize-1:0>;