user manual

8XC251SA, SB, SP, SQ USER’S MANUAL
A-66
Operation: JB
(PC) ← (PC) + 3
IF (bit) = 1
THEN
(PC) ← (PC) + rel
JBC bit51,rel
JBC bit,rel
Function: Jump if bit is set and clear bit
Description: If the specified bit is one, branch to the specified address; otherwise proceed with the next
instruction. The bit is not cleared if it is already a zero. The branch destination is computed
by adding the signed relative displacement in the third instruction byte to the PC, after incre-
menting the PC to the first byte of the next instruction.
Note: When this instruction is used to test an output pin, the value used as the original data
is read from the output data latch, not the input pin.
Flags:
Example: The accumulator contains 56H (01010110B). After the instruction sequence
JBC ACC.3,LABEL1
JBC ACC.2,LABEL2
the accumulator contains 52H (01010010B) and program execution continues at label
LABEL2.
Variations
JBC bit51,rel
Binary Mode Source Mode
Not Taken Taken Not Taken Taken
Bytes: 33 33
States: 47 47
Hex Code in: Binary Mode = [Encoding]
Source Mode = [Encoding]
Operation: JBC
(PC) ← (PC) + 3
IF (bit51) = 1
THEN
(bit51) ← 0
(PC) ← (PC) + rel
CY AC OV N Z
—————
[Encoding] 0 0 0 1 0 0 0 0 bit addr rel. addr