Motorola M68000 User Manual download pdf (Page 54)

Integer Instructions

MOTOROLA M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL 4-13

ADDX Add Extended ADDX

(M68000 Family)

Operation: Source + Destination + X → Destination

Assembler ADDX Dy,Dx

Syntax: ADDX – (Ay), – (Ax)

Attributes: Size = (Byte, Word, Long)

Description: Adds the source operand and the extend bit to the destination operand and

stores the result in the destination location. The operands can be addressed in two

different ways:

1. Data register to data register—The data registers specified in the instruction

contain the operands.

2. Memory to memory—The address registers specified in the instruction address

the operands using the predecrement addressing mode.

The size of the operation can be specified as byte, word, or long.

Condition Codes:

X — Set the same as the carry bit.

N — Set if the result is negative; cleared otherwise.

Z — Cleared if the result is nonzero; unchanged otherwise.

V — Set if an overﬂow occurs; cleared otherwise.

C — Set if a carry is generated; cleared otherwise.

NOTE

Normally, the Z condition code bit is set via programming before

the start of an operation. This allows successful tests for zero

results upon completion of multiple-precision operations.

XNZVC

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Motorola M68000 User Manual Page 54