Renesas TM V.3.20A Especificaciones descargar pdf (Pagina 94)

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Renesas Technology, Tools FAQs

Last Updated: August 7, 2000

Document Number: 01051268_e

I upgraded the NC30WA with a version later than V.3.20 Release 1, and then I started getting a warning. I am concerned that there

may be something wrong in my program.

This warning indicates that the compiler successfully compiled your C program but the object codes may cause a malfunction. The

following describes the two types of warning messages, the reasons they are issued, and the possible problems that may occur.

Warning(ccom): invalid return type

This warning indicates that the return value of a function may be unknown. This will not cause any problems if the return

value is not used in the caller function. But if the return value is used, you need to make sure that an undetermined return

value won't cause a problem in your program.

Warning(ccom): assignment from const pointer to non-const pointer

This warning indicates you are trying to do an "implicit variable type conversion", to input [constant far pointer to the

constants] to [far pointer to the variable] which the compiler thinks it is invalid. If the CPU executes the above operation, the

CPU may perform a write-operation at the address indicating a constant area. Therefore, the compiler sends a warning to you

to make sure a write-operation does not happen at the destination address indicated by the subject pointer.

To prevent this message from being generated, input the pointer after executing the type conversion (cast) on the constant pointer.

[Program Example with Cast Execution]

uchar *addr;

uchar offset;

const uchar * const d_fig[] =

{

000,001,002,003

}

func()

{

addr = (uchar *)d_fig[offset];

}

[Program Example with Warning Generation]

uchar *addr;

uchar offset;

const uchar * const d_fig[] =

{

000,001,002,003

}

func()

{

addr = d_fig[offset]; /* The warning is generated */

}

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