eor

Exclusive OR (A32)

EOR{S}<c> <Rd>, <Rn>, <Rm> {, <shift>}

Performs bitwise XOR.

Pseudocode Operation

result ← Rn XOR (Rm shifted by shift_amount)
Rd ← result
if S == 1 then
  N ← result[31]
  Z ← (result == 0)
  C ← shifter_carry_out
else
  condition_flags unchanged

Example

EOR r0, r1, r2

Encoding

Binary Layout

cond

31:28

0000

27:24

001

23:21

19:16

15:12

imm5

11:7

stype

6:5

3:0

Format Data Proc

Opcode 0x00200000

Extension A32 (Base)

Operands

Rd
Destination general-purpose register
Rn
First source / base general-purpose register
Rm
Second source / offset general-purpose register

Other forms of eor

eor Bitwise Exclusive OR (Immediate)
eor Bitwise Exclusive OR (Register)
eor Vector Bitwise Exclusive OR
eor SVE Bitwise Exclusive OR (Predicated)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction	ISA	Bit pattern
0x02200000	EOR{<c>}{<q>} {<Rd>,} <Rn>, #<const>	A32	cond \| 0010 \| 001 \| 0 \| Rn \| Rd \| imm12
0xF0800000	EOR{<c>}{<q>} {<Rd>,} <Rn>, #<const>	T32	11110 \| i \| 0 \| 0100 \| 0 \| Rn \| 0 \| imm3 \| Rd \| imm8
0x00200060	EOR{<c>}{<q>} {<Rd>,} <Rn>, <Rm>, RRX	A32	cond \| 0000 \| 001 \| 0 \| Rn \| Rd \| 00000 \| 11 \| 0 \| Rm
0x00200000	EOR{<c>}{<q>} {<Rd>,} <Rn>, <Rm> {, <shift> #<amount>}	A32	cond \| 0000 \| 001 \| 0 \| Rn \| Rd \| imm5 \| stype \| 0 \| Rm
0x4040	EOR<c>{<q>} {<Rdn>,} <Rdn>, <Rm>	T32	010000 \| 0001 \| Rm \| Rdn
0xEA800030	EOR{<c>}{<q>} {<Rd>,} <Rn>, <Rm>, RRX	T32	1110101 \| 0100 \| 0 \| Rn \| 0 \| 000 \| Rd \| 00 \| 11 \| Rm
0xEA800000	EOR<c>.W {<Rd>,} <Rn>, <Rm>	T32	1110101 \| 0100 \| 0 \| Rn \| 0 \| imm3 \| Rd \| imm2 \| stype \| Rm
0x00200010	EOR{<c>}{<q>} {<Rd>,} <Rn>, <Rm>, <shift> <Rs>	A32	cond \| 0000 \| 001 \| 0 \| Rn \| Rd \| Rs \| 0 \| stype \| 1 \| Rm

Description

Bitwise Exclusive-OR (register) performs a bitwise exclusive-OR of a register value and an optionally-shifted register value, and writes the result to the destination register. If the destination register is not the PC, the EORS 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:

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    (shifted, carry) = Shift_C(R[m], shift_t, shift_n, PSTATE.C);
    result = R[n] EOR shifted;
    if d == 15 then          // Can only occur for A32 encoding
        if setflags then
            ALUExceptionReturn(result);
        else
            ALUWritePC(result);
    else
        R[d] = result;
        if setflags then
            PSTATE.N = result<31>;
            PSTATE.Z = IsZeroBit(result);
            PSTATE.C = carry;
            // PSTATE.V unchanged

eor