Samsung S3C8275X - Manual (Page 182)

INSTRUCTION SET S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X
6-48
JR
— Jump Relative
JR cc,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)
Bytes Cycles Opcode
(Hex)
Addr Mode
dst
cc | opc 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.