Analog Devices ADSP-BF53x Blackfin Reference page 122

User Mode
case of an interrupt routine, if the service routine is interruptible, the
return address is stored on the stack. For this case, the address can be
found by popping the value from the stack into
loaded, the
RTI
Note the stack pop is optional. If the
pushed/popped, then the interrupt service routine becomes
non-interruptible, because the return address is not saved on the
stack.
The processor remains in User mode until one of these events occurs:
• An interrupt, NMI, or exception event invokes Supervisor mode.
• An emulation event invokes Emulation mode.
• A reset event invokes the Reset state.
Table 3-4. Return Instructions That Can Invoke User Mode
Current Process Activity
Interrupt Service Routine
Exception Service Routine
Nonmaskable Interrupt
Service Routine
Emulation Service Routine
3-6 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
instruction can be issued.
Return Instruction to Use
RTI
RTX
RTN
RTE
. Once
RETI RETI
register is not
RETI
Execution Resumes at
Address in This Register
RETI
RETX
RETN
RETE
has been