<= R13 = R13_svc
R14 = R14_svc
This SWI sets the processor to Supervisor mode. Interrupt and Fast Interrupt status is unaltered. Note that SWI calls while in SVC mode will alter R14, and will use R13 as stack.
To return to User mode call OS_LeaveOS which is present from RISC OS 5, or via the CallASWI module. Using this SWI has the advantage of triggering callbacks on the way back out of the kernel, but if neither of these are options, the following is safe to use in 26 or 32 bit mode:
TEQ PC,PC ; Determine 26 or 32 bit mode
MSREQ CPSR_c,#&10 ; Sets USR32 system
TEQNEP PC,#0 ; Sets USR26 mode, also idempotent so works round StrongARM MSR bug
NOP ; Workaround ARMv2 banked register access after TEQP bug
See PRM 1, page 140.
[sh-index] Back to list of manuals
|
| |
