Question

The linker is reporting multiply defined errors for an inline function.

I have the following code in a header file:

struct Port_Pin
{
    volatile uint32_t *     port_addr_set_value;    //!< Writing the pin value here sets the pin to high.
    volatile uint32_t *     port_addr_clr_value;    //!< Writing the pin value to this port clears the pin to low.
    volatile uint32_t *     port_addr_read_value;   //!< Address to read pin value.
    volatile uint32_t *     port_addr_enable;       //!< Writing the pin value here enables the pin (for reading or writing).
    volatile uint32_t *     port_addr_disable;      //!< Writing the pin value here disables the pin.
    volatile uint32_t *     port_addr_dir_output;   //!< Writing the pin value here sets the pin as an output.
    volatile uint32_t *     port_addr_dir_input;    //!< Writing the pin value here sets the pin as an input.
    unsigned int            pin_bit_position;       //!< Zero based, where position zero is first bit position.
};

inline void
Write_Port_Pin(const struct Port_Pin *  p_port,
               uint8_t                  bit)
{
    volatile uint32_t * port_addr = 0;
    port_addr = ((bit & 1) == 0) ? p_port->port_addr_clr_value
        : p_port->port_addr_set_value;
    *port_addr = 1 << p_port->pin_bit_position;
    return;
}

I include the header file in more than one source (.c) file.

I would like to have the above function pasted inline wherever it is called.
Is there a technique for this without have multiple definitions of the function in each source file that is included? If yes, please provide example.

I need the performance optimization for an embedded platform.
Are compilers or linkers smart enough to inline functions when they are defined in other translation units?

I am using Green Hills compiler, 4.2.4 on an embedded ARM9 platform. Assume pre-2000 C language standard. This is C code not C++.

Answer 1

inline is just a suggestion, not a command. However, in general compilers are smart enough to do the right thing ( and Green Hills has a good reputation in so far as optimizations go ).

Make the function ‘static inline’, which will prevent the compiler from making the symbol exportable. That should fix your multiple definition link errors… the linker is complaining that the same function is exported from several source modules.