SADDW, SADDW2

Signed Add Wide. This instruction adds vector elements of the first source SIMD&FP register to the corresponding vector elements in the lower or upper half of the second source SIMD&FP register, places the results in a vector, and writes the vector to the SIMD&FP destination register.

The SADDW instruction extracts the second source vector from the lower half of the second source register. The SADDW2 instruction extracts the second source vector from the upper half of the second source register.

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.

313029282726252423222120191817161514131211109876543210
0Q001110size1Rm000100RnRd
Uo1

SADDW{2} <Vd>.<Ta>, <Vn>.<Ta>, <Vm>.<Tb>

integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); if size == '11' then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer datasize = 64; integer part = UInt(Q); integer elements = datasize DIV esize; boolean sub_op = (o1 == '1'); boolean unsigned = (U == '1');

Assembler Symbols

2

Is the second and upper half specifier. If present it causes the operation to be performed on the upper 64 bits of the registers holding the narrower elements, and is encoded in Q:

Q 2
0 [absent]
1 [present]
<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<Ta>

Is an arrangement specifier, encoded in size:

size <Ta>
00 8H
01 4S
10 2D
11 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.

<Tb>

Is an arrangement specifier, encoded in size:Q:

size Q <Tb>
00 0 8B
00 1 16B
01 0 4H
01 1 8H
10 0 2S
10 1 4S
11 x RESERVED

Operation

CheckFPAdvSIMDEnabled64(); bits(2*datasize) operand1 = V[n, 2*datasize]; bits(datasize) operand2 = Vpart[m, part, datasize]; bits(2*datasize) result; integer element1; integer element2; integer sum; for e = 0 to elements-1 element1 = Int(Elem[operand1, e, 2*esize], unsigned); element2 = Int(Elem[operand2, e, esize], unsigned); if sub_op then sum = element1 - element2; else sum = element1 + element2; Elem[result, e, 2*esize] = sum<2*esize-1:0>; V[d, 2*datasize] = result;

Operational information

If PSTATE.DIT is 1:


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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