cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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xfs_bit.c (2233B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
      4 * All Rights Reserved.
      5 */
      6#include "xfs.h"
      7#include "xfs_log_format.h"
      8#include "xfs_bit.h"
      9
     10/*
     11 * XFS bit manipulation routines, used in non-realtime code.
     12 */
     13
     14/*
     15 * Return whether bitmap is empty.
     16 * Size is number of words in the bitmap, which is padded to word boundary
     17 * Returns 1 for empty, 0 for non-empty.
     18 */
     19int
     20xfs_bitmap_empty(uint *map, uint size)
     21{
     22	uint i;
     23
     24	for (i = 0; i < size; i++) {
     25		if (map[i] != 0)
     26			return 0;
     27	}
     28
     29	return 1;
     30}
     31
     32/*
     33 * Count the number of contiguous bits set in the bitmap starting with bit
     34 * start_bit.  Size is the size of the bitmap in words.
     35 */
     36int
     37xfs_contig_bits(uint *map, uint	size, uint start_bit)
     38{
     39	uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
     40	uint result = 0;
     41	uint tmp;
     42
     43	size <<= BIT_TO_WORD_SHIFT;
     44
     45	ASSERT(start_bit < size);
     46	size -= start_bit & ~(NBWORD - 1);
     47	start_bit &= (NBWORD - 1);
     48	if (start_bit) {
     49		tmp = *p++;
     50		/* set to one first offset bits prior to start */
     51		tmp |= (~0U >> (NBWORD-start_bit));
     52		if (tmp != ~0U)
     53			goto found;
     54		result += NBWORD;
     55		size -= NBWORD;
     56	}
     57	while (size) {
     58		if ((tmp = *p++) != ~0U)
     59			goto found;
     60		result += NBWORD;
     61		size -= NBWORD;
     62	}
     63	return result - start_bit;
     64found:
     65	return result + ffz(tmp) - start_bit;
     66}
     67
     68/*
     69 * This takes the bit number to start looking from and
     70 * returns the next set bit from there.  It returns -1
     71 * if there are no more bits set or the start bit is
     72 * beyond the end of the bitmap.
     73 *
     74 * Size is the number of words, not bytes, in the bitmap.
     75 */
     76int xfs_next_bit(uint *map, uint size, uint start_bit)
     77{
     78	uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
     79	uint result = start_bit & ~(NBWORD - 1);
     80	uint tmp;
     81
     82	size <<= BIT_TO_WORD_SHIFT;
     83
     84	if (start_bit >= size)
     85		return -1;
     86	size -= result;
     87	start_bit &= (NBWORD - 1);
     88	if (start_bit) {
     89		tmp = *p++;
     90		/* set to zero first offset bits prior to start */
     91		tmp &= (~0U << start_bit);
     92		if (tmp != 0U)
     93			goto found;
     94		result += NBWORD;
     95		size -= NBWORD;
     96	}
     97	while (size) {
     98		if ((tmp = *p++) != 0U)
     99			goto found;
    100		result += NBWORD;
    101		size -= NBWORD;
    102	}
    103	return -1;
    104found:
    105	return result + ffs(tmp) - 1;
    106}