fbeadf50f2
We had two copies of a ffs function for longs with subtly different semantics and, for the one in bitops.h, a confusing name: the result was off-by-one compared to the library function ffsl. Unify the functions into one, and solve the name problem by calling the 0-based functions "bitops_ctzl" and "bitops_ctol" respectively. This also fixes the build on platforms with ffsl, including Mac OS X and Windows. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Tested-by: Andreas Färber <afaerber@suse.de> Tested-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
209 lines
5.6 KiB
C
209 lines
5.6 KiB
C
/*
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* Hierarchical Bitmap Data Type
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*
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* Copyright Red Hat, Inc., 2012
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*
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* Author: Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*/
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#ifndef HBITMAP_H
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#define HBITMAP_H 1
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#include <limits.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include "bitops.h"
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typedef struct HBitmap HBitmap;
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typedef struct HBitmapIter HBitmapIter;
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#define BITS_PER_LEVEL (BITS_PER_LONG == 32 ? 5 : 6)
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/* For 32-bit, the largest that fits in a 4 GiB address space.
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* For 64-bit, the number of sectors in 1 PiB. Good luck, in
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* either case... :)
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*/
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#define HBITMAP_LOG_MAX_SIZE (BITS_PER_LONG == 32 ? 34 : 41)
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/* We need to place a sentinel in level 0 to speed up iteration. Thus,
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* we do this instead of HBITMAP_LOG_MAX_SIZE / BITS_PER_LEVEL. The
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* difference is that it allocates an extra level when HBITMAP_LOG_MAX_SIZE
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* is an exact multiple of BITS_PER_LEVEL.
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*/
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#define HBITMAP_LEVELS ((HBITMAP_LOG_MAX_SIZE / BITS_PER_LEVEL) + 1)
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struct HBitmapIter {
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const HBitmap *hb;
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/* Copied from hb for access in the inline functions (hb is opaque). */
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int granularity;
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/* Entry offset into the last-level array of longs. */
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size_t pos;
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/* The currently-active path in the tree. Each item of cur[i] stores
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* the bits (i.e. the subtrees) yet to be processed under that node.
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*/
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unsigned long cur[HBITMAP_LEVELS];
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};
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/**
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* hbitmap_alloc:
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* @size: Number of bits in the bitmap.
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* @granularity: Granularity of the bitmap. Aligned groups of 2^@granularity
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* bits will be represented by a single bit. Each operation on a
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* range of bits first rounds the bits to determine which group they land
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* in, and then affect the entire set; iteration will only visit the first
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* bit of each group.
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*
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* Allocate a new HBitmap.
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*/
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HBitmap *hbitmap_alloc(uint64_t size, int granularity);
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/**
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* hbitmap_empty:
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* @hb: HBitmap to operate on.
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*
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* Return whether the bitmap is empty.
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*/
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bool hbitmap_empty(const HBitmap *hb);
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/**
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* hbitmap_granularity:
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* @hb: HBitmap to operate on.
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*
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* Return the granularity of the HBitmap.
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*/
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int hbitmap_granularity(const HBitmap *hb);
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/**
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* hbitmap_count:
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* @hb: HBitmap to operate on.
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*
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* Return the number of bits set in the HBitmap.
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*/
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uint64_t hbitmap_count(const HBitmap *hb);
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/**
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* hbitmap_set:
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* @hb: HBitmap to operate on.
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* @start: First bit to set (0-based).
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* @count: Number of bits to set.
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*
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* Set a consecutive range of bits in an HBitmap.
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*/
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void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count);
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/**
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* hbitmap_reset:
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* @hb: HBitmap to operate on.
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* @start: First bit to reset (0-based).
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* @count: Number of bits to reset.
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*
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* Reset a consecutive range of bits in an HBitmap.
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*/
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void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count);
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/**
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* hbitmap_get:
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* @hb: HBitmap to operate on.
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* @item: Bit to query (0-based).
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*
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* Return whether the @item-th bit in an HBitmap is set.
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*/
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bool hbitmap_get(const HBitmap *hb, uint64_t item);
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/**
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* hbitmap_free:
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* @hb: HBitmap to operate on.
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*
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* Free an HBitmap and all of its associated memory.
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*/
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void hbitmap_free(HBitmap *hb);
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/**
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* hbitmap_iter_init:
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* @hbi: HBitmapIter to initialize.
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* @hb: HBitmap to iterate on.
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* @first: First bit to visit (0-based, must be strictly less than the
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* size of the bitmap).
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*
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* Set up @hbi to iterate on the HBitmap @hb. hbitmap_iter_next will return
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* the lowest-numbered bit that is set in @hb, starting at @first.
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*
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* Concurrent setting of bits is acceptable, and will at worst cause the
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* iteration to miss some of those bits. Resetting bits before the current
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* position of the iterator is also okay. However, concurrent resetting of
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* bits can lead to unexpected behavior if the iterator has not yet reached
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* those bits.
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*/
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void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);
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/* hbitmap_iter_skip_words:
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* @hbi: HBitmapIter to operate on.
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*
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* Internal function used by hbitmap_iter_next and hbitmap_iter_next_word.
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*/
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unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi);
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/**
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* hbitmap_iter_next:
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* @hbi: HBitmapIter to operate on.
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*
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* Return the next bit that is set in @hbi's associated HBitmap,
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* or -1 if all remaining bits are zero.
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*/
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static inline int64_t hbitmap_iter_next(HBitmapIter *hbi)
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{
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unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1];
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int64_t item;
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if (cur == 0) {
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cur = hbitmap_iter_skip_words(hbi);
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if (cur == 0) {
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return -1;
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}
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}
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/* The next call will resume work from the next bit. */
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hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
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item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + bitops_ctzl(cur);
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return item << hbi->granularity;
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}
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/**
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* hbitmap_iter_next_word:
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* @hbi: HBitmapIter to operate on.
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* @p_cur: Location where to store the next non-zero word.
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*
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* Return the index of the next nonzero word that is set in @hbi's
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* associated HBitmap, and set *p_cur to the content of that word
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* (bits before the index that was passed to hbitmap_iter_init are
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* trimmed on the first call). Return -1, and set *p_cur to zero,
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* if all remaining words are zero.
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*/
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static inline size_t hbitmap_iter_next_word(HBitmapIter *hbi, unsigned long *p_cur)
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{
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unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1];
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if (cur == 0) {
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cur = hbitmap_iter_skip_words(hbi);
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if (cur == 0) {
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*p_cur = 0;
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return -1;
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}
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}
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/* The next call will resume work from the next word. */
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hbi->cur[HBITMAP_LEVELS - 1] = 0;
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*p_cur = cur;
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return hbi->pos;
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}
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#endif
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