Subtract with Carry, setting flags, subtracts a register value and the value of NOT (Carry flag) from a register value, and writes the result to the destination register. It updates the condition flags based on the result.
This instruction is used by the alias NGCS.
| 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 |
| sf | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | Rm | 0 | 0 | 0 | 0 | 0 | 0 | Rn | Rd | ||||||||||||
| op | S | ||||||||||||||||||||||||||||||
integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer datasize = if sf == '1' then 64 else 32; boolean sub_op = (op == '1'); boolean setflags = (S == '1');
| <Wd> |
Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field. |
| <Wn> |
Is the 32-bit name of the first general-purpose source register, encoded in the "Rn" field. |
| <Wm> |
Is the 32-bit name of the second general-purpose source register, encoded in the "Rm" field. |
| <Xd> |
Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field. |
| <Xn> |
Is the 64-bit name of the first general-purpose source register, encoded in the "Rn" field. |
| <Xm> |
Is the 64-bit name of the second general-purpose source register, encoded in the "Rm" field. |
| Alias | Is preferred when |
|---|---|
| NGCS | Rn == '11111' |
bits(datasize) result; bits(datasize) operand1 = X[n]; bits(datasize) operand2 = X[m]; bits(4) nzcv; if sub_op then operand2 = NOT(operand2); (result, nzcv) = AddWithCarry(operand1, operand2, PSTATE.C); if setflags then PSTATE.<N,Z,C,V> = nzcv; X[d] = result;
If PSTATE.DIT is 1:
Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41
Copyright © 2010-2021 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.