-link some code in RAM paged area(use the FC,FD,FE,and FF RAM pages)
CPU can run code only in "CPU local memory map". See 9S12XEP100 datasheet, Figure 1-2, MC9S12XE100 Global Memory Map. CPU local memory is on the left. CPU program counter register is 16bits wide only, that's 64-k addresses of CPU local memory. CPU runs code in PPAGE-paged/banked memory by mapping 16k memory chunks to PPAGE window in CPU local map at 0x8000-0xBFFF and executing code there. With the help of special CPU instructions, CALL and RTC, which manipulate PPAGE register, you can call routine on PPAGE=y from one PPAGE=x without need to jump to not paged memory. You can't do the same with R-, E- or G-paged memories, you need to switch paged register manually.
The issue that I'm facing is how can I call the functions that are stored in the paged RAM area?I know that for functions placed in the paged flash area, the modifier "@far" in function declaration allows the CALL/RETC instructions to set and restore the PPAGE register, when calling paged functions in flash memory.
But how can a similar mechanism be used for RPAGE register?For calling the functions from paged RAM area I am using a pointer to function table, so at call time I will not
Again, there are no CPU instructions similar to CALL and RTC, that could automatically switch xPAGE register other than PPAGE. You have to set RPAGE manually, then using not paged JSR and RTS you may call and return from routines.
