Vector Multiply Subtract Long multiplies elements of a vector by a scalar, and subtracts the products from corresponding elements of the destination vector. The destination vector elements are twice as long as the elements that are multiplied.
For more information about scalars see Advanced SIMD scalars.
Depending on settings in the CPACR, NSACR, and HCPTR registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
| 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 |
| 1 | 1 | 1 | 1 | 0 | 0 | 1 | U | 1 | D | != 11 | Vn | Vd | 0 | 1 | 1 | 0 | N | 1 | M | 0 | Vm | ||||||||||
| size | op | ||||||||||||||||||||||||||||||
if size == '11' then SEE "Related encodings"; if size == '00' || Vd<0> == '1' then UNDEFINED; constant unsigned = (U == '1'); constant add = (op == '0'); constant floating_point = FALSE; constant long_destination = TRUE; constant d = UInt(D:Vd); constant n = UInt(N:Vn); constant regs = 1; constant integer esize = 8 << UInt(size); constant integer elements = 64 DIV esize; integer m; integer index; if size == '01' then m = UInt(Vm<2:0>); index = UInt(M:Vm<3>); if size == '10' then m = UInt(Vm); index = UInt(M);
| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 1 | U | 1 | 1 | 1 | 1 | 1 | D | != 11 | Vn | Vd | 0 | 1 | 1 | 0 | N | 1 | M | 0 | Vm | ||||||||||
| size | op | ||||||||||||||||||||||||||||||
if size == '11' then SEE "Related encodings"; if size == '00' || Vd<0> == '1' then UNDEFINED; constant unsigned = (U == '1'); constant add = (op == '0'); constant floating_point = FALSE; constant long_destination = TRUE; constant d = UInt(D:Vd); constant n = UInt(N:Vn); constant regs = 1; constant integer esize = 8 << UInt(size); constant integer elements = 64 DIV esize; integer m; integer index; if size == '01' then m = UInt(Vm<2:0>); index = UInt(M:Vm<3>); if size == '10' then m = UInt(Vm); index = UInt(M);
Related encodings: See Advanced SIMD data-processing for the T32 instruction set, or Advanced SIMD data-processing for the A32 instruction set.
| <c> |
For encoding A1: see Standard assembler syntax fields. This encoding must be unconditional. |
|
For encoding T1: see Standard assembler syntax fields. |
| <q> |
| <dt> |
Is the data type for the scalar and the elements of the operand vector,
encoded in
|
| <Qd> |
Is the 128-bit name of the SIMD&FP register holding the accumulate vector, encoded in the "D:Vd" field as <Qd>*2. |
| <Dn> |
Is the 64-bit name of the first SIMD&FP source register, encoded in the "N:Vn" field. |
if ConditionPassed() then EncodingSpecificOperations(); CheckAdvSIMDEnabled(); constant FPCR_Type fpcr = StandardFPCR(); constant op2 = Elem[Din[m],index,esize]; constant op2val = Int(op2, unsigned); for r = 0 to regs-1 for e = 0 to elements-1 constant op1 = Elem[Din[n+r],e,esize]; constant op1val = Int(op1, unsigned); if floating_point then fp_addend = (if add then FPMul(op1,op2,fpcr) else FPNeg(FPMul(op1,op2,fpcr), fpcr)); Elem[D[d+r],e,esize] = FPAdd(Elem[Din[d+r],e,esize], fp_addend, fpcr); else constant addend = if add then op1val*op2val else -op1val*op2val; if long_destination then Elem[Q[d>>1],e,2*esize] = Elem[Qin[d>>1],e,2*esize] + addend; else Elem[D[d+r],e,esize] = Elem[Din[d+r],e,esize] + addend;
If CPSR.DIT is 1 and this instruction passes its condition execution check:
Internal version only: isa v01_31, pseudocode v2024-03_rel ; Build timestamp: 2024-03-25T10:05
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