TMS320F280025C: signification "__interrupt" to declare an interrupt

Part Number: TMS320F280025C

Hi,

Here my code run correctly, but what about  "__interrupt"  to delcare an interrupt because my interrupt doesn't work when I don't declare it like this. When __interrupt is absent  "Adc_index = 0" at each loop turn so my buffer isn't complete. 

__interrupt void isr_adc(void)
{
    // Record ADC value
    Vout_samples[Adc_index] = ADC_readResult(VOUT_ADCRESULTREGBASE, VOUT_ADC_SOC_NO);
    Adc_index++;

    if(Adc_index >= SAMPLES)
    {
        Adc_index = 0;
        adc_bufferfull = 1;
    }

    ADC_clearInterruptStatus(ADCC_BASE, VOUT_ADC_INT_NUMBER);                                                       // Clear the interrupt flag

    if(ADC_getInterruptOverflowStatus(ADCC_BASE, VOUT_ADC_INT_NUMBER) == true)                                      // Check if overflow has occurred
    {
        ADC_clearInterruptOverflowStatus(ADCC_BASE, VOUT_ADC_INT_NUMBER);
        ADC_clearInterruptStatus(ADCC_BASE, VOUT_ADC_INT_NUMBER);
    }

    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP1);                                                              // Acknowledge the interrupt
}

For me the interrupt mapping is make by "Interrupt_register(INT_ADCC1, &isr_adc);". There is more than that ?

Thanks,

Damien