Digital Photo Keychain User Manual

INSTRUCTION DESCRIPTIONS

A - 56 INSTRUCTION SET DETAILS MOTOROLA

Operation: Assembler Syntax:

D[n] ➞ C; BSET #n,X:ea

1 ➞ D[n]

D[n] ➞ C; BSET #n,X:aa

1 ➞ D[n]

D[n] ➞ C; BSET #n,X:pp

1 ➞ D[n]

D[n] ➞ C; BSET #n,Y:ea

1 ➞ D[n]

D[n] ➞ C; BSET #n,Y:aa

1 ➞ D[n]

D[n] ➞ C; BSET #n,Y:pp

1 ➞ D[n]

D[n] ➞ C; BSET #n,D

1 ➞ D[n]

Description: Test the n

bit of the destination operand D, set it, and store the result in

the destination location. The state of the n

bit is stored in the carry bit C of the condition

code register. The bit to be tested is selected by an immediate bit number from 0–23.

This instruction performs a read-modify-write operation on the destination location using

two destination accesses before releasing the bus. This instruction provides a test-and-

set capability which is useful for synchronizing multiple processors using a shared mem-

ory. This instruction can use all memory alterable addressing modes.

Example:

BSET #$0,X:<<$FFE5 ;test and clear bit 14 in I/O Port B Data Reg.

BSET Bit Test and Set

Before Execution After Execution

X:$FFE5

$000000

$0300

$000001