6 tst and teq – ARM VERSION 1.2 User Manual
Page 146
ARM Instruction Reference
4-36
Copyright © 2000, 2001 ARM Limited. All rights reserved.
ARM DUI 0068B
4.3.6
TST and TEQ
Test and Test Equivalence.
Syntax
TST{cond} Rn, Operand2
TEQ{cond} Rn, Operand2
where:
cond
is an optional condition code (see Conditional execution on page 4-4).
Rn
is the ARM register holding the first operand.
Operand2
is a flexible second operand. See Flexible second operand on page 4-24
for details of the options.
Usage
These instructions test the value in a register against
Operand2
. They update the
condition flags on the result, but do not place the result in any register.
The
TST
instruction performs a bitwise AND operation on the value in
Rn
and the value
of
Operand2
. This is the same as a
ANDS
instruction, except that the result is discarded.
The
TEQ
instruction performs a bitwise Exclusive OR operation on the value in
Rn
and
the value of
Operand2
. This is the same as a
EORS
instruction, except that the result is
discarded.
Condition flags
These instructions:
•
update the N and Z flags according to the result
•
can update the C flag during the calculation of
Operand2
(see Flexible second
•
do not affect the V flag.
Use of r15
If you use r15 as
Rn
, the value used is the address of the instruction plus 8.
You cannot use r15 for any operand in any data processing instruction that has a
register-controlled shift (see Flexible second operand on page 4-24).