System Debug Reference Manual (32650-90888)

188 Chapter5
System Debug Command Specifications Fx-LOG
LEV
LEV
Sets the current environment to the specified stack level in the stack markers.
Syntax
LEV [ number ]
LEV [ number ] [ interrupt_level ]
The LEV command changes the current environment to the environment at the specified
stack level.
All commands accurately reflect the register values that are in effect a level change.
Windows also reflect the new level values.
If the CONTINUE or SS command in Debug is issued after changing levels, an implicit LEV 0
is performed.
If any error is encountered during a level change, the environment is automatically set to
stack level 0.
The following algorithm is used to set level
n on the CM stack:
WHILE lev <> desired level DO
Get previous stack marker.
Set Q based on delta-Q in marker.
Set S to Q-4.
Set X based on X in marker.
Set STATUS based on status marker.
Set CMPC based on status and P offset in marker.
Set CIR based on fetch from new value of CMPC.
The following algorithm is used to set level
n on the NM stack:
Get current frame info (based on unwind info);
WHILE lev <> desired level DO
Restore entry save registers (based on frame unwind info);
Get previous frame (based on unwind info);
IF frame is an interrupt stack marker (ISM) THEN
— Restore RP, SP, DP, SR4, SR5, SR0, PCQ from the ISM
ELSE
— Set RP, SP, DP, SR4, to new values from the stack;
— Restore call save registers (based on unwind info);