KS57C2308/P2308/C2316/P2316 SAM47 INSTRUCTION SET
5-59
JR — Jump Relative (Very Short)
JR (Continued)
Examples: 1. A short form for a relative jump to label “KK” is the instruction
JR KK
where “KK” must be within the allowed range of current PC–15 to current PC+16. The JR
instruction has in this case the effect of an unconditional JP instruction.
2. In the following instruction sequence, if the instruction “LD WX, #02H” were to be executed in
place of “LD WX,#00H”, the program would jump to 1004H and “JPS CCC” would be
executed. If “LD EA,#03H” were to be executed, the jump would be to1006H and “JPS DDD”
would be executed.
ORG 1000H
JPS AAA
JPS BBB
JPS CCC
JPS DDD
LD WX,#00H ;WX ← 00H
LD EA,WX
ADS WX,EA ;WX ← (WX) + (WX)
JR @WX ;Current PC13–8 (10H) + WX (00H) = 1000H
;Jump to address 1000H and execute JPS AAA
3. Here is another example:
ORG 1100H
LD A,#0H
LD A,#1H
LD A,#2H
LD A,#3H
LD 30H,A ;Address 30H ← A
JPS YYY
XXX LD EA,#00H ;EA ← 00H
JR @EA ;Jump to address 1100H
;Address 30H ← 00H
If “LD EA,#01H” were to be executed in place of “LD EA,#00H”, the program would jump to
1001H and address 30H would contain the value 1H. If “LD EA,#02H” were to be executed,
the jump would be to 1002H and address 30H would contain the value 2H.