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Instruction Set Description

4.6.3.36 TSTX

* TSTX.A Test destination address-word

* TSTX.[W] Test destination word

* TSTX.B Test destination byte

TSTX.A dst

Syntax

TSTX dst or TSTX.W dst

TSTX.B dst

Operation dst + 0FFFFFh + 1

dst + 0FFFFh + 1

dst + 0FFh + 1

CMPX.A #0,dst

Emulation

CMPX #0,dst

CMPX.B #0,dst

Description The destination operand is compared with zero. The status bits are set according to the

result. The destination is not affected.

Status Bits N: Set if destination is negative, reset if positive

Z: Set if destination contains zero, reset otherwise

C: Set

V: Reset

Mode Bits OSCOFF, CPUOFF, and GIE are not affected.

Example RAM byte LEO is tested; PC is pointing to upper memory. If it is negative, continue at

LEONEG; if it is positive but not zero, continue at LEOPOS.

TSTX.B LEO ; Test LEO

JN LEONEG ; LEO is negative

JZ LEOZERO ; LEO is zero

LEOPOS ...... ; LEO is positive but not zero

LEONEG ...... ; LEO is negative

LEOZERO ...... ; LEO is zero

255

SLAU144J–December 2004–Revised July 2013 CPUX

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