1 files changed, 207 insertions, 0 deletions
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
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+++ b/include/qemu/hbitmap.h
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+/*
+ * Hierarchical Bitmap Data Type
+ *
+ * Copyright Red Hat, Inc., 2012
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef HBITMAP_H
+#define HBITMAP_H 1
+
+#include <limits.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include "bitops.h"
+
+typedef struct HBitmap HBitmap;
+typedef struct HBitmapIter HBitmapIter;
+
+#define BITS_PER_LEVEL         (BITS_PER_LONG == 32 ? 5 : 6)
+
+/* For 32-bit, the largest that fits in a 4 GiB address space.
+ * For 64-bit, the number of sectors in 1 PiB.  Good luck, in
+ * either case... :)
+ */
+#define HBITMAP_LOG_MAX_SIZE   (BITS_PER_LONG == 32 ? 34 : 41)
+
+/* We need to place a sentinel in level 0 to speed up iteration.  Thus,
+ * we do this instead of HBITMAP_LOG_MAX_SIZE / BITS_PER_LEVEL.  The
+ * difference is that it allocates an extra level when HBITMAP_LOG_MAX_SIZE
+ * is an exact multiple of BITS_PER_LEVEL.
+ */
+#define HBITMAP_LEVELS         ((HBITMAP_LOG_MAX_SIZE / BITS_PER_LEVEL) + 1)
+
+struct HBitmapIter {
+    const HBitmap *hb;
+
+    /* Copied from hb for access in the inline functions (hb is opaque).  */
+    int granularity;
+
+    /* Entry offset into the last-level array of longs.  */
+    size_t pos;
+
+    /* The currently-active path in the tree.  Each item of cur[i] stores
+     * the bits (i.e. the subtrees) yet to be processed under that node.
+     */
+    unsigned long cur[HBITMAP_LEVELS];
+};
+
+/**
+ * hbitmap_alloc:
+ * @size: Number of bits in the bitmap.
+ * @granularity: Granularity of the bitmap.  Aligned groups of 2^@granularity
+ * bits will be represented by a single bit.  Each operation on a
+ * range of bits first rounds the bits to determine which group they land
+ * in, and then affect the entire set; iteration will only visit the first
+ * bit of each group.
+ *
+ * Allocate a new HBitmap.
+ */
+HBitmap *hbitmap_alloc(uint64_t size, int granularity);
+
+/**
+ * hbitmap_empty:
+ * @hb: HBitmap to operate on.
+ *
+ * Return whether the bitmap is empty.
+ */
+bool hbitmap_empty(const HBitmap *hb);
+
+/**
+ * hbitmap_granularity:
+ * @hb: HBitmap to operate on.
+ *
+ * Return the granularity of the HBitmap.
+ */
+int hbitmap_granularity(const HBitmap *hb);
+
+/**
+ * hbitmap_count:
+ * @hb: HBitmap to operate on.
+ *
+ * Return the number of bits set in the HBitmap.
+ */
+uint64_t hbitmap_count(const HBitmap *hb);
+
+/**
+ * hbitmap_set:
+ * @hb: HBitmap to operate on.
+ * @start: First bit to set (0-based).
+ * @count: Number of bits to set.
+ *
+ * Set a consecutive range of bits in an HBitmap.
+ */
+void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count);
+
+/**
+ * hbitmap_reset:
+ * @hb: HBitmap to operate on.
+ * @start: First bit to reset (0-based).
+ * @count: Number of bits to reset.
+ *
+ * Reset a consecutive range of bits in an HBitmap.
+ */
+void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count);
+
+/**
+ * hbitmap_get:
+ * @hb: HBitmap to operate on.
+ * @item: Bit to query (0-based).
+ *
+ * Return whether the @item-th bit in an HBitmap is set.
+ */
+bool hbitmap_get(const HBitmap *hb, uint64_t item);
+
+/**
+ * hbitmap_free:
+ * @hb: HBitmap to operate on.
+ *
+ * Free an HBitmap and all of its associated memory.
+ */
+void hbitmap_free(HBitmap *hb);
+
+/**
+ * hbitmap_iter_init:
+ * @hbi: HBitmapIter to initialize.
+ * @hb: HBitmap to iterate on.
+ * @first: First bit to visit (0-based).
+ *
+ * Set up @hbi to iterate on the HBitmap @hb.  hbitmap_iter_next will return
+ * the lowest-numbered bit that is set in @hb, starting at @first.
+ *
+ * Concurrent setting of bits is acceptable, and will at worst cause the
+ * iteration to miss some of those bits.  Resetting bits before the current
+ * position of the iterator is also okay.  However, concurrent resetting of
+ * bits can lead to unexpected behavior if the iterator has not yet reached
+ * those bits.
+ */
+void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);
+
+/* hbitmap_iter_skip_words:
+ * @hbi: HBitmapIter to operate on.
+ *
+ * Internal function used by hbitmap_iter_next and hbitmap_iter_next_word.
+ */
+unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi);
+
+/**
+ * hbitmap_iter_next:
+ * @hbi: HBitmapIter to operate on.
+ *
+ * Return the next bit that is set in @hbi's associated HBitmap,
+ * or -1 if all remaining bits are zero.
+ */
+static inline int64_t hbitmap_iter_next(HBitmapIter *hbi)
+{
+    unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1];
+    int64_t item;
+
+    if (cur == 0) {
+        cur = hbitmap_iter_skip_words(hbi);
+        if (cur == 0) {
+            return -1;
+        }
+    }
+
+    /* The next call will resume work from the next bit.  */
+    hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
+    item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ffsl(cur) - 1;
+
+    return item << hbi->granularity;
+}
+
+/**
+ * hbitmap_iter_next_word:
+ * @hbi: HBitmapIter to operate on.
+ * @p_cur: Location where to store the next non-zero word.
+ *
+ * Return the index of the next nonzero word that is set in @hbi's
+ * associated HBitmap, and set *p_cur to the content of that word
+ * (bits before the index that was passed to hbitmap_iter_init are
+ * trimmed on the first call).  Return -1, and set *p_cur to zero,
+ * if all remaining words are zero.
+ */
+static inline size_t hbitmap_iter_next_word(HBitmapIter *hbi, unsigned long *p_cur)
+{
+    unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1];
+
+    if (cur == 0) {
+        cur = hbitmap_iter_skip_words(hbi);
+        if (cur == 0) {
+            *p_cur = 0;
+            return -1;
+        }
+    }
+
+    /* The next call will resume work from the next word.  */
+    hbi->cur[HBITMAP_LEVELS - 1] = 0;
+    *p_cur = cur;
+    return hbi->pos;
+}
+
+
+#endif