BL51: Warning L16 (Uncalled Segment, Ignored for Overlay)

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Information in this article applies to:

• C51 All Versions

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QUESTION

My simple project has two modules, a C and an Assembly module. I am trying to call one of the C functions from within the assembly module, but each time I build the project I get:

 WARNING 16 : UNCALLED SEGMENT - IGNORED FOR OVERLAY PROCESS.

I have already checked the knowledgebase and have seen several articles relating to this warning, but they don't help. How do I fix this problem?

ANSWER

The following is a solution should accomplish what you are trying to do:

Test.c

void foo(void);    // C function declaration

extern void FOO_CALLER(void);  // referencing a function
                                                     // defined elsewhere - C style

void main(void)
{
   FOO_CALLER();

   while(1);
}

void foo(void)    // C function definition
{
}

Asm_Test.asm

NAME ASMTEST       ; module name

EXTRN CODE (foo)    ; referencing a function defined
                                   ; elsewhere - assembly style

?PR?TSEG?ASM_TEST SEGMENT CODE
PUBLIC  FOO_CALLER     ; assembly routine declaration

RSEG ?PR?TSEG?ASM_TEST
using   0

FOO_CALLER:        ; assembly routine definition
        call foo

   RET
   END

CAUSE

The reason you may be receiving this warning is that although you have an assembly module that calls a C function, the assembly module itself is not being called by anything.

RESOLUTION

As illustrated above, you have to define a routine in your assembly module that calls the C function. The assembly routine then must be called from main or some other function that is called from main in C. Note that programs must have a "main" routine and in this example, the "main" routine is in the C module.

See the Attached Files section below to download an example project.

The actual code for the assembly module was generated using the SRC pragma.

MORE INFORMATION

• Refer to Warning L16 in the BL51 User's Guide.
• Refer to Warning L16 in the LX51 User's Guide.

SEE ALSO

• BL51: Warning 16 (Uncalled Segment, Ignored for Overlay Process)
• BL51: WARNING 16 (UNCALLED SEGMENT, IGNORED FOR OVERLAY ...)
• BL51: Warning 16 (Uncalled Segment...) for Called Function
• BL51: Interrupt Generates Warning 16 (Uncalled Segment)
• RTX51 TINY: Warning 16 (Uncalled Segment)
• BL51: Warning L16 (Uncalled Segment) ?C_INITSEG
• C51: Calling Assembly Routines from C
• GENERAL: Turning off Warnings

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ATTACHED FILES

Request the files attached to this knowledgebase article.

Last Reviewed: Thursday, February 25, 2021

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