CONDITIONAL BRANCH INSTRUCTIONS

CJNE

The CJNE instruction compares the first two operands and branches to the specified destination if their values are not equal. If the values are the same, execution continues with the next instruction.

format	example	Operation	Opcode/ Encoding	Flags affected	Byte	Cycles
CJNE @Rn, #immd,offset	CJNE @R1, #24h,label	PC=PC+3 If (Rn) <>#data PC=PC+offset If(Rn) <#data C=1 Else C=0	1011011n, #imm 8-bit, offset	C	3	2
CJNE A, #data, offset	CJNE A, #01h, label	PC=PC+3 If A <> #immd PC=PC+offset If A<#immd C=1 Else C=0	10110100, #immd, offset	C	3	2
CJNE A, direct, offset	CJNE A, 60h, label	PC=PC+3 If A<> (direct) PC=PC+offset If A < (direct) C=1 Else C=0	10110101, direct 8-bit adder, offset	C	3	2
CJNE Rn, #immd, offset	CJNE R6, #12h, label	PC=PC+3 If Rn <> immediate PC=PC + offset If Rn < immd C=1 Else C=0	10111nnn, #immd 8-bit, offset	C	3	2

 DJNZ

The DJNZ instruction decrements the byte indicated by the first operand and, if the resulting value is not zero, branches to the address specified in the second operand.

format	example	Operation	Opcode/ Encoding	Flags affected	Byte	Cycles
DJNZ direct, offset	DJNZ 40h,label	PC PC+2 (direct)=(direct)-1 If (direct)<>0 PC=PC+offset	11010101, direct addr 8-bit, offset 8-bit	none	3	2
DJNZ Rn, offset	DJNZ R6, Label	PC=PC+2 Rn=Rn-1 If Rn<>0 PC=PC+offset	11011nnn, offset 8-bit	none	2	2

JB

The JB instruction branches to the address specified in the second operand if the value of the bit specified in the first operand is 1. The bit that is tested is not modified. No flags are affected by this instruction.

format	example	Operation	Opcode/Encoding	Flags affected	Byte	Cycles
JB bit, offset	JB P1.2, label	PC=PC+3 If (bit)=1 PC=PC+offset	00100000, bit, offset	none	3	2

JNB

The JNB instruction branches to the specified address if the specified bit operand has a value of 0. Otherwise, execution continues with the next instruction. No flags are affected by this instruction.

format	example	Operation	Opcode/Encoding	Flags affected	Byte	Cycles
JNB bit, offset	JNB P1.3, label	PC=PC+3 If (bit)=0 PC=PC+offset	00100000, bit, offset	none	3	2

JBC

The JBC Jump to branch address if Bit set, clear bit after branch

JBC bit, offset

PC=PC+3

If bit set

then

Jump to specified address if bit is set

clear the bit after

else

continue normal execution
Note
When this instruction is used to modify an output port, the value used as the port data is read from the output data latch, not the input pins of the port.

format	example	Operation	Opcode/Encoding	Flags affected	Byte	Cycles
JBC bit, offset	JBC P1.2, 44h	PC=PC+3 If (bit)=1 (bit)=0 PC=PC+offset	00010000, bit, offset	none	3	2

JC

Jump if carry bit in PSW is set

If not set; execution continues with the next instruction.

No flags are affected by this instruction.

format	example	Operation	Opcode/Encoding	Flags affected	Byte	Cycles
JC  offset	JC label	PC=PC+2 If  C=1 PC=PC+offset	01000000,  offset	none	2	2

JNC

Jump if carry not set (i.e. carry clear)

Otherwise, execution continues with the next instruction.

No flags are affected by this instruction.

format	example	Operation	Opcode/Encoding	Flags affected	Byte	Cycles
JNC  offset	JC label	PC=PC+2 If  C=0 PC=PC+offset	01010000,  offset	none	2	2

JZ

Jump if result in Accumulator is zero

Otherwise, the next instruction is executed.

Neither the accumulator nor any flags are modified by this instruction.

format	example	Operation	Opcode/Encoding	Flags affected	Byte	Cycles
JZ offset	JZ label	PC=PC+2 If  A=0 PC=PC+offset	01100000,  offset	none	2	2

JNZ

The JNZ instruction transfers control to the specified address if the value in the accumulator is not 0. If the accumulator has a value of 0, the next instruction is executed. Neither the accumulator nor any flags are modified by this instruction.

format	example	Operation	Opcode/ Encoding	Flags affected	Byte	Cycles
JNZ offset	JNZ label	PC=PC+2 If  A< >0 PC=PC+offset	01110000,  offset	none	2	2