Filter
Top Products
Architecture
86
n NIS (Non-maskable Interrupt Status)
This bit is set to 1 when a Non-maskable interrupt occurs at the same time as a debug
exception. In this case the Status, Cause, EPC and BadVAddr registers assume their usual
status after the occurrence of a Non-maskable interrupt, but the address in DEPC is not the
non-maskable interrupt exception vector address (0xBFC0 0000).
Instead, 0xBFC0 0000 is put in DEPC by the debug exception handler software, after which
processing returns directly from the debug exception to the Non-maskable interrupt handler.
n OES (Other Exceptions Status)
This bit is set to 1 when an exception other than reset, NmI or UTLB Refill occurs at the same
time as a debug exception. In this case the Status, Cause, EPC and BadVAddr registers
assume their usual status after the occurrence of such an exception, but the address in DEPC
will not be the other exception vector address. Instead, 0xBFC0 0180 (if the Status register
BEV bit is 1) or 0x8000 0080 (if BEV is 0) is put in DEPC by the debug exception handler
software, after which processing returns directly from the debug exception to the other
exception handler.
(Note: Only one of bits NIS, or OES is set, according to the priority of exceptions.)
n TLF (TLB Exception Flag)
This bit is set to 1 when a TLB-related exception (TLB Refill, UTLB Refill, Mod) occurs for
the immediately preceding load or store instruction while a debug exception handler is running
(DM bit = 1).
(Note: A check should be made as to whether a TLB-related exception has occurred or not each
time access is made to the user area data.)
n BsF (Bus Error Exception Flag)
This bit is set to 1 when a bus error exception occurs for a load or store instruction while a
debug exception handler is running (DM bit = 1). It is cleared by writing 0 to it.
n SSt (Single Step) (0 at reset)
This bit indicates whether the single step debug function is enabled (set to 1) or disabled
(cleared to 0). The function is disabled when the DM bit is set to 1, i.e., while a debug
exception handler is running. This bit is a read/write bit.
n DBp (bit 1)
Set to 1 to indicate a Debug Breakpoint exception.