C51: Stack and Reentrant Stack Symbolic Names

Information in this article applies to:

• C51

QUESTION

I wish to perform some debugging on my project and in order to set watchpoints I need to know the symbolic names given to the system stack and reentrant stack pointers. What are they?

ANSWER

The system stack is actually an SFR with the name SP.

The symbolic name of the reentrant stack depends on which memory model you are using:

• Small: ?C_IBP
• Compact: ?C_PBP
• Large: ?C_XBP

You will be able to set watchpoints on these symbols to watch the system stack and reentrant stack pointers. If your debugging software allows it you may be able to do such things as stop execution when the stack pointer reaches the top of IDATA or the system and reentrant stack pointers point to the same location, thus detecting stack overflows.

MORE INFORMATION

• Refer to Reentrant Functions in the Cx51 User's Guide.

SEE ALSO

• C51: Checking for Stack Underflow at Runtime
• C51: Calculating Stack Size
• C51: Stack Pointer Initialization in Startup Code
• C51: Locating the Stack after IDATA Variables
• C51: Stack Usage

Last Reviewed: Thursday, February 25, 2021