Multiple call to segment warning

I am checking the m51 file. I never really studied the map file before, so please help me out here.

The warnings happen when I set optimizer level > 1, which means it is data overlaying causing the problem.

Here is some section of overlay map:

?PR?SPICOMMISR?SPI_COM_CC
>> --- +--> ?CO?SPI_COM_CC

?CO?SPI_COM_CC
>> --- +--> ?PR?SSPIPSE?SPIHANDLERS_CC

?PR?_NVMWRITE?NVMEM_CC
>> 0BH +--> ?CO?NVMEM_CC

So the first one is that Spi ISR call my constant lookup table in code space? What does the second one mean? C51Startup calls main and C_INITSEG (which call ?CO?SENSOR_CC)

So if multiple routines need to access constant in code space, will that cause "Multiple call to segment" warning?

Thanks,

I am checking the m51 file. I never really studied the map file before, so please help me out here.

The warnings happen when I set optimizer level > 1, which means it is data overlaying causing the problem.

Here is some section of overlay map:

?PR?SPICOMMISR?SPI_COM_CC
>> --- +--> ?CO?SPI_COM_CC

?CO?SPI_COM_CC
>> --- +--> ?PR?SSPIPSE?SPIHANDLERS_CC

?PR?_NVMWRITE?NVMEM_CC
>> 0BH +--> ?CO?NVMEM_CC

So the first one is that Spi ISR call my constant lookup table in code space? What does the second one mean? C51Startup calls main and C_INITSEG (which call ?CO?SENSOR_CC)

So if multiple routines need to access constant in code space, will that cause "Multiple call to segment" warning?

Thanks,

one more difference, I did a compile with optimizer set to be 1 then I search ?SPICOMMISR? in the map file.

I find that SPICOMMISR show up in XDATA memory section besides CODE MEMORY and OVERLAY MAP:
XDATA 066FH 0001H UNIT ?XD?SPICOMMISR?SPI_COM_CC

And optimizer set > 1, SPICOMMISR only show up in CODE MEMORY and OVERLAY MAP area. So I guess the data overlaying process move ISR out of xdata space, and somehow mess up other stuff?

Did you take a look at http://www.keil.com/support/man/docs/c51/c51_xf_recursivecode.htm ?

Jon

I don't quite understand that example, but this time I tried to exclude one segment from overlaying analysis and it worked!
thank you!
And last question: how to disable multiple segments from overlaying analysis?
My warnings are:

*** WARNING L15: MULTIPLE CALL TO SEGMENT
    SEGMENT: ?PR?SSPIPSE?SPIHANDLERS_CC
    CALLER1: ?PR?SPICOMMISR?SPI_COM_CC
    CALLER2: ?C_C51STARTUP
*** WARNING L15: MULTIPLE CALL TO SEGMENT
    SEGMENT: ?PR?_NVMWRITE?NVMEM_CC
    CALLER1: ?PR?SPICOMMISR?SPI_COM_CC
    CALLER2: ?C_C51STARTUP

I finally figure it out. Thanks all for the help.
From the link Jon provide, it says:
"automatic overlay analysis cannot be successfully accomplished when references are made via pointers to functions. "

I do have function call via pointer, although I use exactly same method to handle my UART command and the compiler never has any problem with that...

Anyway, once I specific exclude segment from overlaying analysis, the warnings are all gone.

Thanks,

Anyway, once I specific exclude segment from overlaying analysis, the warnings are all gone.

With the scarce resources of the '51 overlaying analysis is almost mandatory for any project greater than blinky. Get rid of the function pointer instead. You may get by without overlaying analysis for now, but some day you may see "data space overflow" and at that time a restructuring, that should be easy now, may be a 'project'.

Erik

Or...

Simply add the function called via pointer into the call tree where it belongs.

Jon

Simply add the function called via pointer into the call tree where it belongs.

What do you mean by that? Is that also through linker settings in Keil?

what I have in my code is this, I define typedef struct:

typedef struct {
        UINT8 Num_Input_Byte;
        void (*cmdFunc)(void);
} cSpiInputStruct_T;

After I receive information from SPI, I check the header then in my super loop, I have this:

void SPIProcess(void)
{
        if (SpiCmdReady)
        {
                cSpiInputTbl[SpiCmdIdx].cmdFunc();
                SpiCmdReady = FALSE;
        }
}

I am using similar method to handle UART command too and never have any problem there.

What do you mean by that? Is that also through linker settings in Keil?

Yes. Take a look at the linker manual. There is an entire chapter devoted to this topic.

www.keil.com/.../bl51_ol_manipulations.htm

Jon