CCS/MSP430G2553: USCI(SPI) Interrupt and Timer interrupt

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;	// Stop watchdog timer

    init_SMS50();  // init clk,comparator, coresponding PINs
    init_clk();
    initSPI();

    __bis_SR_register(GIE);

    while(1)
	{
    	__no_operation();
	}
}

// cycle counter
#pragma vector=TIMER0_A0_VECTOR
__interrupt void Timer0_A0_Compare(void)
{	TA0CCTL0 &= ~CCIFG; //clear interrupt flag

	 comp_out = BIT0 & CACTL2;  // catch comparator output
	 P2OUT = BIT0 & (~comp_out);  // inverte P2.0 as ~Q
	 NOC ++;  // increment NOC
	 if(comp_out)	NO1++;  //incrment NO1 if Q:HIGH

	 if( NOC == MEASURE_CYCLES)
	 {
		ratio = (float) 100*NO1/NOC;  // save ratio in buffer [%]
		NOC = 0;
		NO1 = 0;
	 }
}


#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0RX_VECTOR))) USCI0RX_ISR (void)
#else
#error Compiler not supported!
#endif
{
	uca0_rx_val = UCA0RXBUF;
	switch(SlaveMode)
	{
		case RX_REG_ADDRESS_MODE:		//prapare for tranmission
			TransmitIndex = 0;
			if(uca0_rx_val == MOISTURE_RATE)
			{
				TXByteCtr  = RATE_LENGTH;
				CopyArray(RATE,TransmitBuffer,RATE_LENGTH);
			}
			else if(uca0_rx_val == MOISTURE_VALUE)
			{
				TXByteCtr  = VALUE_LENGTH;
				CopyArray(VALUE,TransmitBuffer,VALUE_LENGTH);
			}
			SendUCA0Data(TransmitBuffer[TransmitIndex++]);	//transmit first byte
			TXByteCtr--;
			SlaveMode = TX_DATA_MODE;
			break;
		case TX_DATA_MODE:
			if(TXByteCtr > 0)
			{
				SendUCA0Data(TransmitBuffer[TransmitIndex++]);
				TXByteCtr--;
			}
			if(TXByteCtr == 0)
			{
				SlaveMode = IDLE_MODE;
			}
			break;
		case IDLE_MODE:
			SlaveMode = RX_REG_ADDRESS_MODE;
			break;
		default:break;
	}

}