UHADD
Unsigned halving add
This instruction adds corresponding unsigned integer values
from the two source SIMD&FP registers, shifts each result right one bit,
places the results into a vector,
and writes the vector to the destination
SIMD&FP register.
The results are
truncated. For rounded results, see URHADD.
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
0
0
0
0
0
1
UHADD <Vd>.<T>, <Vn>.<T>, <Vm>.<T>
if size == '11' then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
constant integer esize = 8 << UInt(size);
constant integer datasize = 64 << UInt(Q);
constant integer elements = datasize DIV esize;
<Vd>
Is the name of the SIMD&FP destination register, encoded in the "Rd" field.
<T>
Is an arrangement specifier,
size
Q
<T>
00
0
8B
00
1
16B
01
0
4H
01
1
8H
10
0
2S
10
1
4S
11
x
RESERVED
<Vn>
Is the name of the first SIMD&FP source register, encoded in the "Rn" field.
<Vm>
Is the name of the second SIMD&FP source register, encoded in the "Rm" field.
CheckFPAdvSIMDEnabled64();
constant bits(datasize) operand1 = V[n, datasize];
constant bits(datasize) operand2 = V[m, datasize];
bits(datasize) result;
integer element1;
integer element2;
integer sum;
for e = 0 to elements-1
element1 = UInt(Elem[operand1, e, esize]);
element2 = UInt(Elem[operand2, e, esize]);
sum = (element1 + element2) >> 1;
Elem[result, e, esize] = sum<esize-1:0>;
V[d, datasize] = result;