static int __init isapnp_isolate()

in isapnp/core.c [280:345]

• 63 lines of code
• 13 McCabe index (conditional complexity)

static int __init isapnp_isolate(void)
{
	unsigned char checksum = 0x6a;
	unsigned char chksum = 0x00;
	unsigned char bit = 0x00;
	int data;
	int csn = 0;
	int i;
	int iteration = 1;

	isapnp_rdp = 0x213;
	if (isapnp_isolate_rdp_select() < 0)
		return -1;

	while (1) {
		for (i = 1; i <= 64; i++) {
			data = read_data() << 8;
			udelay(250);
			data = data | read_data();
			udelay(250);
			if (data == 0x55aa)
				bit = 0x01;
			checksum =
			    ((((checksum ^ (checksum >> 1)) & 0x01) ^ bit) << 7)
			    | (checksum >> 1);
			bit = 0x00;
		}
		for (i = 65; i <= 72; i++) {
			data = read_data() << 8;
			udelay(250);
			data = data | read_data();
			udelay(250);
			if (data == 0x55aa)
				chksum |= (1 << (i - 65));
		}
		if (checksum != 0x00 && checksum == chksum) {
			csn++;

			isapnp_write_byte(0x06, csn);
			udelay(250);
			iteration++;
			isapnp_wake(0x00);
			isapnp_set_rdp();
			udelay(1000);
			write_address(0x01);
			udelay(1000);
			goto __next;
		}
		if (iteration == 1) {
			isapnp_rdp += RDP_STEP;
			if (isapnp_isolate_rdp_select() < 0)
				return -1;
		} else if (iteration > 1) {
			break;
		}
__next:
		if (csn == 255)
			break;
		checksum = 0x6a;
		chksum = 0x00;
		bit = 0x00;
	}
	isapnp_wait();
	isapnp_csn_count = csn;
	return csn;
}