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BSET - Test a bit and set

Operation

[Z] ← ¬(<bit number> OF [destination])
<bit number> OF [destination] ← 1

Syntax

BSET Dn,<ea>
BSET #<data>,<ea>

Attributes

Size byte, longword

Description

A bit in the destination operand is tested and the state of the specified bit is reflected in the condition of the Z-bit of the condition code. After the test, the specified bit is set in the destination. If a data register is the destination then the bit numbering is modulo 32, allowing bit manipulation of all bits in a data register. If a memory location is the destination, a byte is read from that location, the bit operation performed using bit number modulo 8, and the byte written back to the location. Bit zero refers to the least-significant bit. The bit number for this operation may be specified either by an immediate value or dynamically by the contents of a data register.

Condition codes

X N Z V C
- - * - -

Z: set if the bit tested is zero, cleared otherwise.

Destination operand addressing mode for BSET Dn,<ea> form

Dn An (An) (An)+ ‑(An) (d,An) (d,An,Xi) ABS.W ABS.L (d,PC) (d,PC,Xn) imm

Note that data register direct (i.e., Dn) addressing uses a longword operand, while all other modes use a byte operand.

From MOTOROLA M68000 FAMILY Programmer's reference manual. Copyright 1992 by Motorola Inc./NXP. Adapted with permission.