Subtract with carry long (bottom)
Subtract the even-numbered elements of the first source vector and the inverted 1-bit carry from the least-significant bit of the odd-numbered elements of the second source vector from the even-numbered elements of the destination and accumulator vector. The 1-bit carry output is placed in the corresponding odd-numbered element of the destination vector.
| 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 |
| 0 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | sz | 0 | Zm | 1 | 1 | 0 | 1 | 0 | 0 | Zn | Zda | ||||||||||||
| T | |||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 32 << UInt(sz); constant integer n = UInt(Zn); constant integer m = UInt(Zm); constant integer da = UInt(Zda);
| <Zda> |
Is the name of the third source and destination scalable vector register, encoded in the "Zda" field. |
| <T> |
Is the size specifier,
encoded in
|
| <Zn> |
Is the name of the first source scalable vector register, encoded in the "Zn" field. |
| <Zm> |
Is the name of the second source scalable vector register, encoded in the "Zm" field. |
CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer pairs = VL DIV (esize * 2); constant bits(VL) operand = Z[n, VL]; constant bits(VL) carries = Z[m, VL]; bits(VL) result = Z[da, VL]; for p = 0 to pairs-1 constant bits(esize) element1 = Elem[result, 2*p + 0, esize]; constant bits(esize) element2 = Elem[operand, 2*p + 0, esize]; constant bit carry_in = Elem[carries, 2*p + 1, esize]<0>; (res, nzcv) = AddWithCarry(element1, NOT(element2), carry_in); carry_out = nzcv<1>; Elem[result, 2*p + 0, esize] = res; Elem[result, 2*p + 1, esize] = ZeroExtend(carry_out, esize); Z[da, VL] = result;
If FEAT_SVE2 is implemented or FEAT_SME is implemented, then if PSTATE.DIT is 1:
This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is constrained unpredictable:
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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