PCAP_ADC_MAXQ
pcap->adc_head = (pcap->adc_head + 1) & (PCAP_ADC_MAXQ - 1);
pcap->adc_tail = (pcap->adc_tail + 1) & (PCAP_ADC_MAXQ - 1);
for (i = 0; i < PCAP_ADC_MAXQ; i++)
struct pcap_adc_request *adc_queue[PCAP_ADC_MAXQ];