static int w1_ds2438_change_config_bit()

in slaves/w1_ds2438.c [137:194]

• 45 lines of code
• 10 McCabe index (conditional complexity)

static int w1_ds2438_change_config_bit(struct w1_slave *sl, u8 mask, u8 value)
{
	unsigned int retries = W1_DS2438_RETRIES;
	u8 w1_buf[3];
	u8 status;
	int perform_write = 0;

	while (retries--) {
		if (w1_reset_select_slave(sl))
			continue;
		w1_buf[0] = W1_DS2438_RECALL_MEMORY;
		w1_buf[1] = 0x00;
		w1_write_block(sl->master, w1_buf, 2);

		if (w1_reset_select_slave(sl))
			continue;
		w1_buf[0] = W1_DS2438_READ_SCRATCH;
		w1_buf[1] = 0x00;
		w1_write_block(sl->master, w1_buf, 2);

		/* reading one byte of result */
		status = w1_read_8(sl->master);

		/* if bit0=1, set a value to a mask for easy compare */
		if (value)
			value = mask;

		if ((status & mask) == value)
			return 0;	/* already set as requested */

		/* changing bit */
		status ^= mask;
		perform_write = 1;

		break;
	}

	if (perform_write) {
		retries = W1_DS2438_RETRIES;
		while (retries--) {
			if (w1_reset_select_slave(sl))
				continue;
			w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
			w1_buf[1] = 0x00;
			w1_buf[2] = status;
			w1_write_block(sl->master, w1_buf, 3);

			if (w1_reset_select_slave(sl))
				continue;
			w1_buf[0] = W1_DS2438_COPY_SCRATCH;
			w1_buf[1] = 0x00;
			w1_write_block(sl->master, w1_buf, 2);

			return 0;
		}
	}
	return -1;
}