How i can allocate dynamically memory to a function

[Majidmanzoor]

it is possible that i write program memory with hex code(a complete program) when there is already a program is running.both at diff addresses. its kind of bootloader. but hex code is stored in external EEPROM. using I2c i write that in flash memory.is that works or not?????
2nd thing is that i want to replace a function of a complete program using same idea as above.

 

[arthur0]

Yes, I've done it and it works.
A number of conditions must be fulfilled for this to work:

1. you didn't say which uC you use, but it needs to programmatically be able to write its own flash (I did it on NEC's 78k0, Silabs' 8051 and TI's CC2430);
2. if there's no ROM support for writing the flash, you'll need to write a short routine that you relocate in RAM (not all uC can run code from RAM), since you won't be able to execute code from flash while writing it;
3. the function you're replacing must be completely relocatable, and you might need to redirect all calls to it through a vector at a fixed location (as the interrupt service routines do).

There are a lot of other complications you might run into so you'll need a proper design and to master the linker and its configuration to succeed.

Arthur