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Solving L107 _DATA_GROUP Overflows

Jeffery Bahr

This is only my second project with Keil, so I am not an expert, but I have Please read the manual'ed. :) The code I'm working on was released by the manufacturer of the system, which includes an embedded 8051. The original code worked, but was poorly written and lacked functionality. As I am making changes, I find that I hit CODE and DATA overflows. I can solve CODE overflows by moving code to other code banks and simplifying things. DATA overflows are a little more difficult.

The Memory Model is "Small: variables in DATA" and the Code Rom Size is "Large: 64K program". I'd prefer not to mess with these, as I have to give the code back working and reasonably like how I got it. The main source file (which is not overlayed) has a small allocation of RAM/dataspace, most of it being used by the ROM code that I can't modify. I've gotten rid of local variables and used XDATA wherever possible. Suddenly, after days of development (and probably 100 builds), I've overflowed DATA by 9 bytes somehow.

*** ERROR L107: ADDRESS SPACE OVERFLOW
    SPACE:   DATA
    SEGMENT: _DATA_GROUP_
    LENGTH:  0009H

My RAM map looks like:

            * * * * * * *   D A T A   M E M O R Y   * * * * * * *
            REG     0000H     0008H     ABSOLUTE     "REG BANK 0"
            DATA    0008H     0018H     ABSOLUTE
            BIT     0020H.0   000FH.5   ABSOLUTE
            BIT     002FH.5   0000H.2   UNIT         _BIT_GROUP_
                    002FH.7   0000H.1                *** GAP ***
            DATA    0030H     0045H     ABSOLUTE
            IDATA   0075H     0006H     UNIT         ?ID?RAMPROG
                    007BH     0001H                  *** GAP ***
            DATA    007CH     0002H     ABSOLUTE
            DATA    007EH     0002H     ABSOLUTE
            IDATA   0080H     0043H     ABSOLUTE
                    00C3H     000DH                  *** GAP ***
            IDATA   00D0H     0030H     ABSOLUTE

I'm assuming that the ABSOLUTE DATA allocations are for C function arguments and local variables -- except that I have now very little/few of either. In fact, the module's compiler output says:

MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =   8573    ----
   CONSTANT SIZE    =    284    ----
   XDATA SIZE       =   ----      16
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----      10
   IDATA SIZE       =      6    ----
   BIT SIZE         =   ----       2
END OF MODULE INFORMATION.

which actually shows less DATA, IDATA and CONSTANTs used than when I first started. So I guess the question is:

1. If I've eliminated EVERY SINGLE local variable in the code, and
2. Reduced the C function parameters to just a small number, all BYTE data types.

what's left to do to eliminate the DATA overflow?

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