Samsung S3F80JB manual JR Jump Relative, Example Given The carry flag = 1 and Labelx = 1FF7H

INSTRUCTION SETS3F80JB

JR — Jump Relative

JRcc,dst

Operation: If cc is true, PC ← PC + dst

If the condition specified by the condition code (cc) is true, the relative address is added to the program counter and control passes to the statement whose address is now in the program counter; otherwise, the instruction following the JR instruction is executed. (See list of condition codes).

The range of the relative address is +127, –128, and the original value of the program counter is taken to be the address of the first instruction byte following the JR statement.

Flags: No flags are affected.

Format:

(1)

cc opc dst

Bytes	Cycles	Opcode	Addr Mode
		(Hex)	dst
2	6	ccB	RA
		cc = 0 to F

NOTE: In the first byte of the two-byte instruction format, the condition code and the opcode are each four bits.

Example: Given: The carry flag = "1" and LABEL_X = 1FF7H:

JR C,LABEL_X → PC = 1FF7H

If the carry flag is set (that is, if the condition code is true), the statement "JR C,LABEL_X" will pass control to the statement whose address is now in the PC. Otherwise, the program instruction following the JR would be executed.

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