static int perf_rdr_read_ubuf()

in kernel/perf.c [656:699]

• 35 lines of code
• 8 McCabe index (conditional complexity)

static int perf_rdr_read_ubuf(uint32_t	rdr_num, uint64_t *buffer)
{
	uint64_t	data, data_mask = 0;
	uint32_t	width, xbits, i;
	const struct rdr_tbl_ent *tentry;

	tentry = perf_rdr_get_entry(rdr_num);
	if ((width = tentry->width) == 0)
		return 0;

	/* Clear out buffer */
	i = tentry->num_words;
	while (i--) {
		buffer[i] = 0;
	}

	/* Check for bits an even number of 64 */
	if ((xbits = width & 0x03f) != 0) {
		data_mask = 1;
		data_mask <<= (64 - xbits);
		data_mask--;
	}

	/* Grab all of the data */
	i = tentry->num_words;
	while (i--) {

		if (perf_processor_interface == ONYX_INTF) {
			data = perf_rdr_shift_in_U(rdr_num, width);
		} else {
			data = perf_rdr_shift_in_W(rdr_num, width);
		}
		if (xbits) {
			buffer[i] |= (data << (64 - xbits));
			if (i) {
				buffer[i-1] |= ((data >> xbits) & data_mask);
			}
		} else {
			buffer[i] = data;
		}
	}

	return 1;
}