Fujitsu F2MC-8FX manual Index Register IX and Extra Pointer EP

CHAPTER 3 REGISTERS

3.5Index Register (IX) and Extra Pointer (EP)

The index register (IX) and extra pointer (EP) are 16-bit application-specific registers existing in the CPU.

The index register (IX) adds an 8-bit offset value with its sign to generate the address stored by the operand.

The extra pointer (EP) indicates the address stored by the operand.

■Index Register (IX)

Figure 3.5-1indicates the operation of the index register.

Figure 3.5-1 Operation of Index Register (IX)

Before execution			MEMORY	After execution	MEMORY
A	XXXXH	56CFH	A	1234H	56CFH
IX	5678H	56CEH	34H	5678H	56CEH	34H
			IX		56CDH
		56CDH	12H			12H
		56CCH	MOVW A, @IX+55H 5678H+0055H		56CCH
			+	= 56CDH

■Extra Pointer (EP)

Figure 3.5-2shows the operation of the extra pointer.

Figure 3.5-2 Operation of the Extra Pointer (EP)

Before execution			MEMORY	After execution			MEMORY
A	XXXXH	5679H	34H	A	1234H	5679H	34H
EP	5678H	5678H	12H	EP	5678H	5678H	12H
		5677H				5677H
		5676H		MOVW A, @EP		5676H

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