Count Register (Ctr) - IBM PowerPC 405GP User Manual

Table 3-2. PPC40SGP SPRs
Function Register Access Page
Configuration CCRO Privileged 4-11
Branch Control
CTR User 3-7
LR User 3-8
DAC1 DAC2
I
Privileged 12-14
DBCRO
DBCR1 I
Privileged 12-9
Debug DBSR
Privileged
12-12
DVC1 DVC2
I
Privileged 12-15
IAC1
IAC2
IIAC3 IIAC4
Privileged
12-14
ICDBDR Privileged 4-14
Fixed-point Exception XER
User 3-8
SPRGO
SPRG1 ISPRG2 ISPRG3
Privileged 3-11
General-Purpose SPR SPRG4
SPRG5 ISPRG6 ISPRG7 User read, privileged write
3-11
USPRGO User 3-11
DEAR Privileged 10-34
ESR Privileged 10-31
Interrupts and Exceptions EVPR
Privileged 10-31
SRRO
SRR1
I
Privileged 10-29
SRR2 SRR3
I
Privileged 10-30
Processor Version PVR Privileged, read-only 3-12
DCCR Privileged 6-17
DCWR Privileged 6-17
ICCR Privileged 6-17
Storage Attribute Control SGR
Privileged 6-17
SLER Privileged 6-17
SUOR Privileged 6-17
TBL TBU
j
Privileged, write-only 11-2
Timer Facilities
PIT Privileged 11-2
TCR Privileged 11-9
TSR Privileged 11-8
Zone Protection ZPR Privileged 6-13
3.3.2.1 Count Register (CTR)
The eTR is written from a GPR using mtspr. The eTR contents can be used as a loop count that is
decremented and tested by some branch instructions. Alternatively, the eTR contents can specify a
target address for the bcctr instruction, enabling branching to any address.
The eTR is in the user programming model.
Preliminary Programming Model 3-7