I'm using an 8051 like controller.
In the past I worked with an other micro and his compiler and I was able to reserve a memory zone to place my "not to be initiated" variables.
With the old compiler I could use the following lines in my code:
#pragma memory=dataseg( NOINIT ) unsigned char dummy; #pragma memory=default
to place the variable dummy into the segment NOINIT. Then in the linker control file I could define the segment NOINIT in a chosen memory zone and then in the cstartup I could not initiate that memory zone. In this way I could choose to place variables in two different memory zone and have them zeroed at every reset or not.
Searching in the manual I found the keyword _at_, but it's slight different because in my example I didn't have to care about placing my NOINIT varibles, it was the linker who did it, while with the _at_ keyword I have to care for every variable and be careful not to overlap to an existing one. Is there a way to do what I need with C51 V7.50 and BL51 V5.12? Thanks in advance.
dead easy in assembler have your XDATA in an assembler module and make a .h that has them as extern for your C
Erik
example assembler for 8k RAM. You also need to modify startup.a51 to exclude the clearing
PUBLIC ..... ?XD?mcxdata SEGMENT XDATA RSEG ?XD?mcxdata firstone: ds 0 ....: ds ... lastone: ds 0 ;; these 16 bytes are not cleared by startup @@@@@@@@@@@@@@@ ds (01ff0h -(lastone - firstone)) ......: ds 1 end