warningをとる（外す）には

../ADCm328P.c:231:1: warning: control reaches end of non-void function

warning:が出るのですが、どの様にしたらとれますか？

mainの中にb16toLED();を記述すると、とれるのですが。

int b16toLED()
{
unsigned char tbup,tblow,msk,n;
msk = 0x01;

tbup=0xAA; tblow=0x55;

for(n=0;n<8;n++)// 0 1 2 3 4 5 6 7
{
tblow = tblow>>n;//0111 0111-->0011 1011

if(tblow &= msk)
{
PORTB |= _BV(0);//b0=1

PORTB &= ~_BV(1);//Clk ↓
PORTB |= _BV(1); //Clk ↑
}
else
{
PORTB &= ~_BV(0);//b0=0

PORTB &= ~_BV(1);//Clk ↓
PORTB |= _BV(1); //Clk ↑
}
tblow = tblow >> 1 ;
}//n=0 --> n<8
}

//***************************
int main(void)
{

port_init();//

unsigned int BADC0,BADC1,BADC2,BADC3,BADC4,BADC5;
//------------------------------------

while(1)
{

while( (ADCSRA & 0x40) != 0 );// Wait Conversion End (ADSC=0 ?) 0b0100 0000

ADMUX = 0x00;// REFS1 REFS0 ADLR ----- MUX3_ MUX2_ MUX1_ MUX0_ ref=AREF ADLR=0(Right)

_delay_us(1);

ADCSRA = 0xC0;// ADEN_ ADSC_ ADATE ADIF_ ADIE_ ADOS2 ADPS1 ADPS0 ADEN=1,ADSC=1 ADC0 Start ADC

while( (ADCSRA & 0x40) != 0 );// Wait Conversion End (ADSC=0 ?) 0b0100 0000

//* ADSC=0 *
BADC0 = ADC;

b16toLED();
}
}