ARM R4F Computer Hardware User Manual


 
Cycle Timings and Interlock Behavior
ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 14-5
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14.1.5 Assembler language syntax
The syntax used throughout this chapter is unified assembler and the timings apply to ARM and
Thumb instructions.
Early Reg The specified registers are required at the start of the Ex1 stage. Add one cycle to the Result Latency
of the instruction producing this register.
Very Early Reg The specified registers are required at the start of the Iss stage. Add two cycles to the Result Latency
of the instruction producing this register, or one cycle if the instruction producing this register is an
LDM
,
LDR
,
LDRD
,
LDREX
, or
LDRT
. The lower Result Latency does not apply if this register is the base register of
the load instruction producing this register, or if the load instruction is an
LDRB
,
LDRBT
,
LDRH
,
LDRSB
, or
LDRSH
.
Interlock There is a data dependency between two instructions in the pipeline, resulting in the Iss stage being
stalled until the processor resolves the dependency.
Table 14-1 Definition of cycle timing terms (continued)
Term Description