Re: [avr-gcc-list] inline vs. #define

[E. Weddington]

On 25 Mar 2003 at 13:23, Andreas Trenkwalder wrote:

> Hi,
> 
> How are inline functions handled by avr-gcc?
> 
> if i use 
> #define i2c_wait() while (!(TWCR & _BV(TWINT)))
> 
> avr-size says: 
> text     data     bss     dec     hex filename
> 388         0       1     389     185 i2c.elf
> 
> 
> instead if i use 
> inline void i2c_wait(void) 
> {
>  while (!(TWCR & _BV(TWINT)));
> }
> 
> avr-size output looks like
> text     data     bss     dec     hex filename
> 398         0       1     399     18f i2c.elf
> 
> Why is there a difference in size?

Take a look at the mixed C and assembly listing. You'll see that 
functions incur an overhead with prolog and epilog code. Inlined 
functions don't have this overhead.

Eric