10b61f8a4SDave Chinner // SPDX-License-Identifier: GPL-2.0
21cfc4a9cSDave Chinner /*
31cfc4a9cSDave Chinner * Copyright (c) 2000-2005 Silicon Graphics, Inc.
41cfc4a9cSDave Chinner * All Rights Reserved.
51cfc4a9cSDave Chinner */
61cfc4a9cSDave Chinner #include "xfs.h"
71cfc4a9cSDave Chinner #include "xfs_log_format.h"
85f213ddbSDarrick J. Wong #include "xfs_bit.h"
91cfc4a9cSDave Chinner
101cfc4a9cSDave Chinner /*
111cfc4a9cSDave Chinner * XFS bit manipulation routines, used in non-realtime code.
121cfc4a9cSDave Chinner */
131cfc4a9cSDave Chinner
141cfc4a9cSDave Chinner /*
151cfc4a9cSDave Chinner * Return whether bitmap is empty.
161cfc4a9cSDave Chinner * Size is number of words in the bitmap, which is padded to word boundary
171cfc4a9cSDave Chinner * Returns 1 for empty, 0 for non-empty.
181cfc4a9cSDave Chinner */
191cfc4a9cSDave Chinner int
xfs_bitmap_empty(uint * map,uint size)201cfc4a9cSDave Chinner xfs_bitmap_empty(uint *map, uint size)
211cfc4a9cSDave Chinner {
221cfc4a9cSDave Chinner uint i;
231cfc4a9cSDave Chinner
241cfc4a9cSDave Chinner for (i = 0; i < size; i++) {
251d4292bfSJia He if (map[i] != 0)
261d4292bfSJia He return 0;
271cfc4a9cSDave Chinner }
281cfc4a9cSDave Chinner
291d4292bfSJia He return 1;
301cfc4a9cSDave Chinner }
311cfc4a9cSDave Chinner
321cfc4a9cSDave Chinner /*
331cfc4a9cSDave Chinner * Count the number of contiguous bits set in the bitmap starting with bit
341cfc4a9cSDave Chinner * start_bit. Size is the size of the bitmap in words.
351cfc4a9cSDave Chinner */
361cfc4a9cSDave Chinner int
xfs_contig_bits(uint * map,uint size,uint start_bit)371cfc4a9cSDave Chinner xfs_contig_bits(uint *map, uint size, uint start_bit)
381cfc4a9cSDave Chinner {
391cfc4a9cSDave Chinner uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
401cfc4a9cSDave Chinner uint result = 0;
411cfc4a9cSDave Chinner uint tmp;
421cfc4a9cSDave Chinner
431cfc4a9cSDave Chinner size <<= BIT_TO_WORD_SHIFT;
441cfc4a9cSDave Chinner
451cfc4a9cSDave Chinner ASSERT(start_bit < size);
461cfc4a9cSDave Chinner size -= start_bit & ~(NBWORD - 1);
471cfc4a9cSDave Chinner start_bit &= (NBWORD - 1);
481cfc4a9cSDave Chinner if (start_bit) {
491cfc4a9cSDave Chinner tmp = *p++;
501cfc4a9cSDave Chinner /* set to one first offset bits prior to start */
511cfc4a9cSDave Chinner tmp |= (~0U >> (NBWORD-start_bit));
521cfc4a9cSDave Chinner if (tmp != ~0U)
531cfc4a9cSDave Chinner goto found;
541cfc4a9cSDave Chinner result += NBWORD;
551cfc4a9cSDave Chinner size -= NBWORD;
561cfc4a9cSDave Chinner }
571cfc4a9cSDave Chinner while (size) {
581cfc4a9cSDave Chinner if ((tmp = *p++) != ~0U)
591cfc4a9cSDave Chinner goto found;
601cfc4a9cSDave Chinner result += NBWORD;
611cfc4a9cSDave Chinner size -= NBWORD;
621cfc4a9cSDave Chinner }
631cfc4a9cSDave Chinner return result - start_bit;
641cfc4a9cSDave Chinner found:
651cfc4a9cSDave Chinner return result + ffz(tmp) - start_bit;
661cfc4a9cSDave Chinner }
671cfc4a9cSDave Chinner
681cfc4a9cSDave Chinner /*
691cfc4a9cSDave Chinner * This takes the bit number to start looking from and
701cfc4a9cSDave Chinner * returns the next set bit from there. It returns -1
711cfc4a9cSDave Chinner * if there are no more bits set or the start bit is
721cfc4a9cSDave Chinner * beyond the end of the bitmap.
731cfc4a9cSDave Chinner *
741cfc4a9cSDave Chinner * Size is the number of words, not bytes, in the bitmap.
751cfc4a9cSDave Chinner */
xfs_next_bit(uint * map,uint size,uint start_bit)761cfc4a9cSDave Chinner int xfs_next_bit(uint *map, uint size, uint start_bit)
771cfc4a9cSDave Chinner {
781cfc4a9cSDave Chinner uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
791cfc4a9cSDave Chinner uint result = start_bit & ~(NBWORD - 1);
801cfc4a9cSDave Chinner uint tmp;
811cfc4a9cSDave Chinner
821cfc4a9cSDave Chinner size <<= BIT_TO_WORD_SHIFT;
831cfc4a9cSDave Chinner
841cfc4a9cSDave Chinner if (start_bit >= size)
851cfc4a9cSDave Chinner return -1;
861cfc4a9cSDave Chinner size -= result;
871cfc4a9cSDave Chinner start_bit &= (NBWORD - 1);
881cfc4a9cSDave Chinner if (start_bit) {
891cfc4a9cSDave Chinner tmp = *p++;
901cfc4a9cSDave Chinner /* set to zero first offset bits prior to start */
911cfc4a9cSDave Chinner tmp &= (~0U << start_bit);
921cfc4a9cSDave Chinner if (tmp != 0U)
931cfc4a9cSDave Chinner goto found;
941cfc4a9cSDave Chinner result += NBWORD;
951cfc4a9cSDave Chinner size -= NBWORD;
961cfc4a9cSDave Chinner }
971cfc4a9cSDave Chinner while (size) {
981cfc4a9cSDave Chinner if ((tmp = *p++) != 0U)
991cfc4a9cSDave Chinner goto found;
1001cfc4a9cSDave Chinner result += NBWORD;
1011cfc4a9cSDave Chinner size -= NBWORD;
1021cfc4a9cSDave Chinner }
1031cfc4a9cSDave Chinner return -1;
1041cfc4a9cSDave Chinner found:
1051cfc4a9cSDave Chinner return result + ffs(tmp) - 1;
1061cfc4a9cSDave Chinner }
107