Datasheet

Chapter 2. ColdFire Core 2-23
Features and Enhancements
Figure 2-1. ColdFire Enhanced Pipeline
2.1.2.1 Instruction Fetch Pipeline (IFP)
Because the fetch and execution pipelines are decoupled by an eight-instruction FIFO
buffer, the IFP can prefetch instructions before the OEP needs them, minimizing stalls.
2.1.2.1.1 Branch Acceleration
Because the IFP and the OEP are decoupled by the instruction buffer, the increased depth
of the IFP is generally hidden from the OEP’s instruction execution. The one exception is
change-of-flow instructions such as unconditional branches or jumps, subroutine calls, and
taken conditional branches. To minimize the effects of the increased depth of the IFP, the
prefetched instruction stream is monitored for change-of-flow opcodes. When certain types
of change-of-flow instructions are detected, the target instruction address is calculated, and
fetching immediately begins in the target stream.
Instruction
Instruction
FIFO
Decode & Select,
Address
Data[31:0]
Instruction
Fetch Cycle 2
Instruction
IAG
IC1
IC2
IED
IB
DSOC
AGEX
Address [31:0]
Instruction Buffer
Address
Generation
Fetch Cycle 1
Early Decode
Generation,
Execute
Operand Fetch
Operand
Execution
Pipeline
Instruction
Fetch
Pipeline
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eescale S
emiconduct
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