Extended branch mnemonics that incorporate the bo field and a partial bi field

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The extended branch mnemonics instruction format when the BO field and BI field are incorporated.

When the BO field and a partial BI field are incorporated, the instruction format is one of the following:

  • mnemonic BIF, target_addr
  • mnemonic target_addr

where the BIF operand specifies the CR field number (0-7) and the target_addr operand specifies the target address. If CR0 is used, the BIF operand can be omitted.

Based on the bits definition in the CR field, the following set of codes has been defined for the most common combinations of branch conditions:

Branch Code Meaning
lt less than *
eq equal to *
gt greater than *
so summary overflow *
le less than or equal to * (not greater than)
ge greater than or equal to * (not less than)
ne not equal to *
ns not summary overflow *
nl not less than
ng not greater than
z zero
nu not unordered (after floating-point comparison)
nz not zero
un unordered (after floating-point comparison)

The assembler supports six encoding values for the BO operand:

  • Branch if condition true (BO=12):
    POWER® family PowerPC®
    bxx bxx
    bxxa bxxa
    bxxl bxxl
    bxxla bxxla
    bxxr bxxlr
    bxxrl bxxlrl
    bxxc bxxctr
    bxxcl bxxctrl
    where xx specifies a BI operand branch code of lt, gt, eq, so, z, or un.
  • Branch if condition false (BO=04):
    POWER® family PowerPC®
    bxx bxx
    bxxa bxxa
    bxxl bxxl
    bxxla bxxla
    bxxr bxxlr
    bxxrl bxxlrl
    bxxc bxxctr
    bxxcl bxxctrl
    where xx specifies a BI operand branch code of ge, le, ne, ns, nl, ng, nz, or nu.
  • Decrement CTR, then branch if CTR is nonzero and condition is true (BO=08):
    • bdnxx
    where xx specifies a BI operand branch code of lt, gt, eq, or so (marked by an * (asterisk) in the Branch Code list).
  • Decrement CTR, then branch if CTR is nonzero and condition is false (BO=00):
    • bdnxx
    where xx specifies a BI operand branch code of le, ge, ne, or ns (marked by an * (asterisk) in the Branch Code list).
  • Decrement CTR, then branch if CTR is zero and condition is true (BO=10):
    • bdzxx
    where xx specifies a BI operand branch code of lt, gt, eq, or so (marked by an * (asterisk) in the Branch Code list).
  • Decrement CTR, then branch if CTR is zero and condition is false (BO=02):
    • bdzxx
    where xx specifies a BI operand branch code of le, ge, ne, or ns (marked by an * (asterisk) in the Branch Code list).