C251: Copying Functions to RAM for Execution

Information in this article applies to:

• C251 Version 2.14 and Later

QUESTION

I wish to copy some C functions to RAM from Flash memory so they can be executed there while I erase my Flash. How can this be achieved? Reassigning a function pointer does not work.

ANSWER

The only way to achieve this is with the following steps:

1. Place your C functions to be copied into a seperate source file and add

   #pragma SRC
   

2. Compile to generate the optimized assembly code for the C functions.
3. Edit the assembly code so the functions are completely relocatable. Absolute addresses must NOT be used.

4. Write a custom copying routine to copy the assembly functions from Flash to RAM.

Reassigning a function pointer will simply make the pointer point to a new area of memory. The function will not be copied.

MORE INFORMATION

• Refer to SRC in the Cx51 User's Guide.

Last Reviewed: Thursday, February 25, 2021