Reverse Subtract with Carry (immediate) subtracts a register value and the value of NOT (Carry flag) from an immediate value, and writes the result to the destination register.
If the destination register is not the PC, the RSCS variant of the instruction updates the condition flags based on the result.
The field descriptions for <Rd> identify the encodings where the PC is permitted as the destination register. ARM deprecates any use of these encodings. However, when the destination register is the PC:
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 |
!= 1111 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | S | Rn | Rd | imm12 | ||||||||||||||||||||
cond |
d = UInt(Rd); n = UInt(Rn); setflags = (S == '1'); imm32 = A32ExpandImm(imm12);
<c> |
<q> |
<Rn> |
Is the general-purpose source register, encoded in the "Rn" field. The PC can be used, but this is deprecated. |
<const> |
An immediate value. See Modified immediate constants in A32 instructions for the range of values. |
if ConditionPassed() then EncodingSpecificOperations(); (result, nzcv) = AddWithCarry(NOT(R[n]), imm32, PSTATE.C); if d == 15 then if setflags then ALUExceptionReturn(result); else ALUWritePC(result); else R[d] = result; if setflags then PSTATE.<N,Z,C,V> = nzcv;
Internal version only: isa v00_79, pseudocode v34.2 ; Build timestamp: 2017-12-19T15:42
Copyright © 2010-2017 ARM Limited or its affiliates. All rights reserved. This document is Non-Confidential.