Stereo System User Manual

MOTOROLA DSP96002 USER’S MANUAL A - 63

BTST Bit Test BTST

Operation:

S{n} → C

Assembler Syntax:

BTST #bit,X: ea

BTST #bit,X: aa

BTST #bit,X: pp

BTST #bit,Y: ea

BTST #bit,Y: aa

BTST #bit,Y: pp

BTST #bit,S

Description:

The nth bit of the source operand is tested and the state of the nth bit is reflected in the C condition code

bit. All memory alterable addressing modes may be used. Register Direct, Absolute Short and I/O Short

addressing may also be used.

The bit to be tested is selected by an immediate bit number 0-31. When used with the appropriate rotate

instructions, this instruction is useful for serial to parallel conversions.

If the system stack register SSH is specified as a source operand, the system stack pointer SP is postdec-

remented by 1 after SSH is read.

CCR Condition Codes:

C - Set if bit tested is set. Cleared otherwise.

V - Not affected.

Z - Not affected.

N - Not affected.

I - Not affected.

LR - Not affected.

–

R - Not affected.

A - Not affected.

ER Status Bits: Not affected.

IER Flags: Not affected.