TEQ (register)

Test Equivalence (register) performs a bitwise exclusive-OR operation on a register value and an optionally-shifted register value. It updates the condition flags based on the result, and discards the result.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1

313029282726252423222120191817161514131211109876543210
!= 111100010011Rn(0)(0)(0)(0)imm5stype0Rm
cond

Rotate right with extend (imm5 == 00000 && stype == 11)

TEQ{<c>}{<q>} <Rn>, <Rm>, RRX

Shift or rotate by value (!(imm5 == 00000 && stype == 11))

TEQ{<c>}{<q>} <Rn>, <Rm> {, <shift> #<amount>}

n = UInt(Rn); m = UInt(Rm); (shift_t, shift_n) = DecodeImmShift(stype, imm5);

T1

15141312111098765432101514131211109876543210
111010101001Rn(0)imm31111imm2stypeRm

Rotate right with extend (imm3 == 000 && imm2 == 00 && stype == 11)

TEQ{<c>}{<q>} <Rn>, <Rm>, RRX

Shift or rotate by value (!(imm3 == 000 && imm2 == 00 && stype == 11))

TEQ{<c>}{<q>} <Rn>, <Rm> {, <shift> #<amount>}

n = UInt(Rn); m = UInt(Rm); (shift_t, shift_n) = DecodeImmShift(stype, imm3:imm2); if n == 15 || m == 15 then UNPREDICTABLE; // Armv8-A removes UNPREDICTABLE for R13

For more information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors.

Assembler Symbols

<c>

See Standard assembler syntax fields.

<q>

See Standard assembler syntax fields.

<Rn>

For encoding A1: is the first general-purpose source register, encoded in the "Rn" field. The PC can be used, but this is deprecated.

For encoding T1: is the first general-purpose source register, encoded in the "Rn" field.

<Rm>

For encoding A1: is the second general-purpose source register, encoded in the "Rm" field. The PC can be used, but this is deprecated.

For encoding T1: is the second general-purpose source register, encoded in the "Rm" field.

<shift>

Is the type of shift to be applied to the second source register, encoded in stype:

stype <shift>
00 LSL
01 LSR
10 ASR
11 ROR
<amount>

For encoding A1: is the shift amount, in the range 1 to 31 (when <shift> = LSL or ROR) or 1 to 32 (when <shift> = LSR or ASR) encoded in the "imm5" field as <amount> modulo 32.

For encoding T1: is the shift amount, in the range 1 to 31 (when <shift> = LSL or ROR) or 1 to 32 (when <shift> = LSR or ASR), encoded in the "imm3:imm2" field as <amount> modulo 32.

Operation

if ConditionPassed() then EncodingSpecificOperations(); (shifted, carry) = Shift_C(R[m], shift_t, shift_n, PSTATE.C); result = R[n] EOR shifted; PSTATE.N = result<31>; PSTATE.Z = IsZeroBit(result); PSTATE.C = carry; // PSTATE.V unchanged

Operational information

If CPSR.DIT is 1, this instruction has passed its condition execution check, and does not use R15 as either its source or destination:


Internal version only: isa v01_31, pseudocode v2023-06_rel, sve v2023-06_rel ; Build timestamp: 2023-07-04T18:06

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