Bxx - Conditionnal jumps

Affected Flags
C	V	N	Z

bxx

: branch if xx condition is meet

Conditional jump instructions change the processor execution flow when conditions are meet. The conditions depends on the status flags which reflects the result of the last instruction affecting flags. So, the conditional instructions will react depending on the result of the last instruction. All these branch instructions uses relative jump coded in 16 bits format. So, these can be used to jump to a location from -32768 to +32767 from the instruction located after the jump instruction. The relative jump mean your code can be relocated without problems. Use jmp if you want to jump to a more distant destination.

Forms and variants

Form	Effect
beq #label	Branch if equal(z=1)
bne #label	Branch if not equal (z=0)
bcc #label	Branch if carry clear (c=0)
bcs #label	Branch if carry set (c=1)
bvc #label	Branch if overflow clear (v=0)
bvs #label	Branch if overflow set (v=0)
bpl #label	Branch if negative clear(n=1)
bmi #label	Branch if negative set (n=0)
bhi #label	Branch if higher (C=1, Z=0)
bhs #label	Branch if higher or same (C=1, same as bcs)
bls #label	Branch if lower or same (C=0 && Z=1)
blo #label	Branch if lower ( c=0, same as bcc )
bhi.s #label	Signed Branch if higher ( z=0 && n==v)
bhs.s #label	Signed Branch if higher or same (n==v)
bls.s #label	Signed Branch if lower or same (z==1 && n!=v)
blo.s #label	Signed Branch if lower (n!=v)
bso #label	Branch if shift overflow (c!=n)
bra #label	Branch in all cases

Instruction encoding

S = Number of the register containing shift count
D = Shifted register number

Instruction	Op Code	Cycles	Encoding
beq #16BitsSignedValue	1C	8	00011100 IIIIIIII IIIIIIII
bne #16BitsSignedValue	1D	8	00011101 IIIIIIII IIIIIIII
bcc #16BitsSignedValue	5E	8	01011110 IIIIIIII IIIIIIII
bcs #16BitsSignedValue	5F	8	01011111 IIIIIIII IIIIIIII
bvc #16BitsSignedValue	5C	8	01011100 IIIIIIII IIIIIIII
bvs #16BitsSignedValue	5D	8	01011101 IIIIIIII IIIIIIII
bmi #16BitsSignedValue	1F	8	00011111 IIIIIIII IIIIIIII
bpl #16BitsSignedValue	1E	8	00011110 IIIIIIII IIIIIIII
bhi #16BitsSignedValue	9C	8	10011100 IIIIIIII IIIIIIII
bhs #16BitsSignedValue	9D	8	10011101 IIIIIIII IIIIIIII
bls #16BitsSignedValue	9E	8	10011110 IIIIIIII IIIIIIII
blo #16BitsSignedValue	9F	8	10011111 IIIIIIII IIIIIIII
bhi.s #16BitsSignedValue	DC	8	11011100 IIIIIIII IIIIIIII
bhs.s #16BitsSignedValue	DD	8	11011101 IIIIIIII IIIIIIII
bls.s #16BitsSignedValue	DE	8	11011110 IIIIIIII IIIIIIII
blo.s #16BitsSignedValue	DF	8	11011111 IIIIIIII IIIIIIII
bso #16BitsSignedValue	20	8	00100000 IIIIIIII IIIIIIII
bra #16BitsSignedValue	60	8	01100000 IIIIIIII IIIIIIII

Code Examples

// Example : Todo...

Bxx - Conditionnal jumps

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