topic Why is rtlib.bss above __bss_addr = .; in the LCF in Digital Signal Controllers

Why is rtlib.bss above __bss_addr = .; in the LCF

j___ — Fri, 29 Jun 2018 21:12:11 GMT

I have noticed in the DSC LCF and documentation examples, that rtlib.bss and rtlib.bss.lo is above the pointer for the RAM copy routine. See excerpt from demo project below. Also, see this in the documentation at:

Targeting MC56F83xx/DSP5685x Controllers, page 137. There are many more examples in the documents.

Why is this?

How does it get copied to RAM?

Regards,

-----------------------------------------------------------------------------------

        .ApplicationData :
        {
              # save space for the pROM data copy
              . = __xRAM_data_start + __data_size;

              # .bss sections
              * (rtlib.bss.lo)       #<<---- rtlib.bss above waterline marker\pointer
              * (rtlib.bss)                 #<<---- rtlib.bss above waterline marker\pointer
              . = ALIGN(4);
              F_Xbss_start_addr = .; #<<---- Marker\Address\Pointer to bss Start
              _START_BSS = .;
              * (.bss.char)         # used if "Emit Separate Char Data Section" enabled
              * (.bss)
              _END_BSS   = .;
              F_Xbss_length = _END_BSS - _START_BSS;

/* Setup the HEAP address */

-----------------------------------------------------------------------------------

Re: Why is rtlib.bss above __bss_addr = .; in the LCF

xiangjun_rong — Tue, 03 Jul 2018 06:08:29 GMT

Hi, Jim,

As you know that the MSL_C_56800E.lib and Runtime_56800E.lib are integrated in the project, so the LCF file has to allocate space for them.

We provide the source code for the library, pls refer to the directory:

C:\Program Files (x86)\Freescale\CodeWarrior for DSC56800E v8.3\M56800E Support

Hope it can help you

Xiangjun Rong

Re: Why is rtlib.bss above __bss_addr = .; in the LCF

j___ — Tue, 03 Jul 2018 14:06:33 GMT

This does not answer the question.

Yes, of course, the LCF has to allocate space for them. BUT, it can do that whether it is above or below ". = __xRAM_data_start + __data_size;". Why is it always above ". = __xRAM_data_start + __data_size;". And, because it is above that, how does it get copied out?

Re: Why is rtlib.bss above __bss_addr = .; in the LCF

xiangjun_rong — Wed, 04 Jul 2018 03:04:12 GMT

Hi, Jim,

Regarding the line in LCF ". = __xRAM_data_start + __data_size;", it just allocate memory space with __data_size bytes. For example if the original address __xRAM_data_start is 0x1000, and the __data_size is 0x200, after the line, the current address . is 0x1200.

Hope it can help you

xiangjun rong