C51: Contents of The ?C_INITSEG Segment

Information in this article applies to:

• C51 any Version
• CX51 any Version

QUESTION

What is the content of segment ?C_INITSEG? In the linker MAP file I have found a segment named ?C_INITSEG. Why is this segment generated and what is the use of this segment?

ANSWER

The ?C_INITSEG segment contains variable initialization information for variables in the memory areas data, idata, pdata, xdata, and far. Entries in this segment are generated when you write C statements like:

  int i = 0x1000;

  void main (void)  {
  }

The contents of the ?C_INITSEG table is used in the INIT.A51 code that runs after the STARTUP.A51 code.

Initialized variables in the memory areas code and far const are directly inserted into the ROM image and do not require an entry in the ?C_INITSEG segment. The same is true for the memory type xdata when you are using the XCROM directive. XCROM directs the compiler to store const xdata variables directly in ROM and suppresses the initialization table entry.

MORE INFORMATION

• Refer to Variable Initialization Code in the Cx51 User's Guide.
• Refer to XCROM in the Cx51 User's Guide.

SEE ALSO

• C51: Modifying the Startup Routines
• C51: Is STARTUP.A51 Required?
• C51: Default Startup and Initialization Code
• C51: Avoiding Startup Initialization of Static Variables

Last Reviewed: Thursday, February 25, 2021