user manual

MicroBlaze Processor Reference Guide www.xilinx.com 81

UG081 (v6.0) June 1, 2006 1-800-255-7778

Instructions

bge

Branch if Greater or Equal

Description

Branch if rA is greater or equal to 0, to the instruction locatedin the offset value of rB. The

target of the branch will be the instruction at address PC + rB.

The mnemonic bged will set the D bit. The D bit determines whether there is a branch

delay slot or not. If the D bit is set, it means that there is a delay slot and the instruction

following thebranch (i.e.in the branch delay slot) is allowed tocomplete executionbefore

executingthe targetinstruction.If the Dbit isnot set, itmeans that thereis no delayslot, so

the instruction to be executed after the branch is the target instruction.

Pseudocode

If rA >= 0 then

← PC + rB

else

← PC + 4

if D = 1 then

allow following instruction to complete execution

Registers Altered

• PC

Latency

1 cycle (if branch is not taken)

2 cycles (if branch is taken and the D bit is set)

3 cycles (if branch is taken and the D bit is not set)

Note

A delay slot must not be used by the following: IMM, branch, or break instructions. This

also applies to instructions causing recoverable exceptions (e.g. unalignement), when

hardware exceptions are enabled. Interrupts and external hardware breaks are deferred

until after the delay slot branch has been completed.

bge rA, rB Branch if Greater or Equal

bged rA, rB Branch if Greater or Equal with Delay

1 0 0 1 1 1 D 0 1 0 1 rA rB 0 0 0 0 0 0 0 0 0 0 0

0 6 11 16 21 31