Analog Devices ADSP-BF535 Blackfin, Hardware Reference Manual

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User Mode
3-4 ADSP-BF535 Blackfin Processor Hardware Reference
Protected Resources and Instructions
System resources consist of a subset of the processor registers, all MMRs,
and a subset of protected instructions. These system and core MMRs are
located starting at address 0xFFC0 0000. This region of memory is pro-
tected from User mode access. Attempts to access MMR space in User
mode cause an exception.
A list of protected instructions appears in Table 3-3 . Attempts to issue any
of the protected instructions from User mode causes an exception event.
Table 3-2. Registers Accessible in User Mode
Processor Registers Register Names
Data Registers
R[7:0]
,
A[1:0]
Pointer Registers
P[5:0]
,
SP
,
FP
,
I[3:0]
,
M[3:0]
,
L[3:0]
,
B[3:0]
Sequencer and Status Registers
RETS
,
LC[1:0]
,
LT[1:0]
,
LB[1:0]
,
ASTAT
,
CYCLES
,
CYCLES2
Table 3-3. Protected Instructions
Instruction Description
RTI Return from Interrupt
RTX Return from Exception
RTN Return from NMI
CLI Disable Interrupts
STI Enable Interrupts
RAISE Force Interrupt/Reset
IDLE Idle
RTE Return from Emulation
Causes an exception only if executed outside Emulation mode