// SPDX-License-Identifier: GPL-2.0-only
/*
* Sparse bit array
*
* Copyright (C) 2018, Google LLC.
* Copyright (C) 2018, Red Hat, Inc. (code style cleanup and fuzzing driver)
*
* This library provides functions to support a memory efficient bit array,
* with an index size of 2^64. A sparsebit array is allocated through
* the use sparsebit_alloc() and free'd via sparsebit_free(),
* such as in the following:
*
* struct sparsebit *s;
* s = sparsebit_alloc();
* sparsebit_free(&s);
*
* The struct sparsebit type resolves down to a struct sparsebit.
* Note that, sparsebit_free() takes a pointer to the sparsebit
* structure. This is so that sparsebit_free() is able to poison
* the pointer (e.g. set it to NULL) to the struct sparsebit before
* returning to the caller.
*
* Between the return of sparsebit_alloc() and the call of
* sparsebit_free(), there are multiple query and modifying operations
* that can be performed on the allocated sparsebit array. All of
* these operations take as a parameter the value returned from
* sparsebit_alloc() and most also take a bit index. Frequently
* used routines include:
*
* ---- Query Operations
* sparsebit_is_set(s, idx)
* sparsebit_is_clear(s, idx)
* sparsebit_any_set(s)
* sparsebit_first_set(s)
* sparsebit_next_set(s, prev_idx)
*
* ---- Modifying Operations
* sparsebit_set(s, idx)
* sparsebit_clear(s, idx)
* sparsebit_set_num(s, idx, num);
* sparsebit_clear_num(s, idx, num);
*
* A common operation, is to itterate over all the bits set in a test
* sparsebit array. This can be done via code with the following structure:
*
* sparsebit_idx_t idx;
* if (sparsebit_any_set(s)) {
* idx = sparsebit_first_set(s);
* do {
* ...
* idx = sparsebit_next_set(s, idx);
* } while (idx != 0);
* }
*
* The index of the first bit set needs to be obtained via
* sparsebit_first_set(), because sparsebit_next_set(), needs
* the index of the previously set. The sparsebit_idx_t type is
* unsigned, so there is no previous index before 0 that is available.
* Also, the call to sparsebit_first_set() is not made unless there
* is at least 1 bit in the array set. This is because sparsebit_first_set()
* aborts if sparsebit_first_set() is called with no bits set.
* It is the callers responsibility to assure that the
* sparsebit array has at least a single bit set before calling
* sparsebit_first_set().
*
* ==== Implementation Overview ====
* For the most part the internal implementation of sparsebit is
* opaque to the caller. One important implementation detail that the
* caller may need to be aware of is the spatial complexity of the
* implementation. This implementation of a sparsebit array is not
* only sparse, in that it uses memory proportional to the number of bits
* set. It is also efficient in memory usage when most of the bits are
* set.
*
* At a high-level the state of the bit settings are maintained through
* the use of a binary-search tree, where each node contains at least
* the following members:
*
* typedef uint64_t sparsebit_idx_t;
* typedef uint64_t sparsebit_num_t;
*
* sparsebit_idx_t idx;
* uint32_t mask;
* sparsebit_num_t num_after;
*
* The idx member contains the bit index of the first bit described by this
* node, while the mask member stores the setting of the first 32-bits.
* The setting of the bit at idx + n, where 0 <= n < 32, is located in the
* mask member at 1 << n.
*
* Nodes are sorted by idx and the bits described by two nodes will never
* overlap. The idx member is always aligned to the mask size, i.e. a
* multiple of 32.
*
* Beyond a typical implementation, the nodes in this implementation also
* contains a member named num_after. The num_after member holds the
* number of bits immediately after the mask bits that are contiguously set.
* The use of the num_after member allows this implementation to efficiently
* represent cases where most bits are set. For example, the case of all
* but the last two bits set, is represented by the following two nodes:
*
* node 0 - idx: 0x0 mask: 0xffffffff num_after: 0xffffffffffffffc0
* node 1 - idx: 0xffffffffffffffe0 mask: 0x3fffffff num_after: 0
*
* ==== Invariants ====
* This implementation usses the following invariants:
*
* + Node are only used to represent bits that are set.
* Nodes with a mask of 0 and num_after of 0 are not allowed.
*
* + Sum of bits set in all the nodes is equal to the value of
* the struct sparsebit_pvt num_set member.
*
* + The setting of at least one bit is always described in a nodes
* mask (mask >= 1).
*
* + A node with all mask bits set only occurs when the last bit
* described by the previous node is not equal to this nodes
* starting index - 1. All such occurences of this condition are
* avoided by moving the setting of the nodes mask bits into
* the previous nodes num_after setting.
*
* + Node starting index is evenly divisible by the number of bits
* within a nodes mask member.
*
* + Nodes never represent a range of bits that wrap around the
* highest supported index.
*
* (idx + MASK_BITS + num_after - 1) <= ((sparsebit_idx_t) 0) - 1)
*
* As a consequence of the above, the num_after member of a node
* will always be <=:
*
* maximum_index - nodes_starting_index - number_of_mask_bits
*
* + Nodes within the binary search tree are sorted based on each
* nodes starting index.
*
* + The range of bits described by any two nodes do not overlap. The
* range of bits described by a single node is:
*
* start: node->idx
* end (inclusive): node->idx + MASK_BITS + node->num_after - 1;
*
* Note, at times these invariants are temporarily violated for a
* specific portion of the code. For example, when setting a mask
* bit, there is a small delay between when the mask bit is set and the
* value in the struct sparsebit_pvt num_set member is updated. Other
* temporary violations occur when node_split() is called with a specified
* index and assures that a node where its mask represents the bit
* at the specified index exists. At times to do this node_split()
* must split an existing node into two nodes or create a node that
* has no bits set. Such temporary violations must be corrected before
* returning to the caller. These corrections are typically performed
* by the local function node_reduce().
*/
#include "test_util.h"
#include "sparsebit.h"
#include <limits.h>
#include <assert.h>
#define DUMP_LINE_MAX 100 /* Does not include indent amount */
typedef uint32_t mask_t;
#define MASK_BITS (sizeof(mask_t) * CHAR_BIT)
struct node {
struct node *parent;
struct node *left;
struct node *right;
sparsebit_idx_t idx; /* index of least-significant bit in mask */
sparsebit_num_t num_after; /* num contiguously set after mask */
mask_t mask;
};
struct sparsebit {
/*
* Points to root node of the binary search
* tree. Equal to NULL when no bits are set in
* the entire sparsebit array.
*/
struct node *root;
/*
* A redundant count of the total number of bits set. Used for
* diagnostic purposes and to change the time complexity of
* sparsebit_num_set() from O(n) to O(1).
* Note: Due to overflow, a value of 0 means none or all set.
*/
sparsebit_num_t num_set;
};
/* Returns the number of set bits described by the settings
* of the node pointed to by nodep.
*/
static sparsebit_num_t node_num_set(struct node *nodep)
{
return nodep->num_after + __builtin_popcount(nodep->mask);
}
/* Returns a pointer to the node that describes the
* lowest bit index.
*/
static struct node *node_first(const struct sparsebit *s)
{
struct node *nodep;
for (nodep = s->root; nodep && nodep->left; nodep = nodep->left)
;
return nodep;
}
/* Returns a pointer to the node that describes the
* lowest bit index > the index of the node pointed to by np.
* Returns NULL if no node with a higher index exists.
*/
static struct node *node_next(const struct sparsebit *s, struct node *np)
{
struct node *nodep = np;
/*
* If current node has a right child, next node is the left-most
* of the right child.
*/
if (nodep->right) {
for (nodep = nodep->right; nodep->left; nodep = nodep->left)
;
return nodep;
}
/*
* No right child. Go up until node is left child of a parent.
* That parent is then the next node.
*/
while (nodep->parent && nodep == nodep->parent->right)
nodep = nodep->parent;
return nodep->parent;
}
/* Searches for and returns a pointer to the node that describes the
* highest index < the index of the node pointed to by np.
* Returns NULL if no node with a lower index exists.
*/
static struct node *node_prev(const struct sparsebit *s, struct node *np)
{
struct node *nodep = np;
/*
* If current node has a left child, next node is the right-most
* of the left child.
*/
if (nodep->left) {
for (nodep = nodep->left; nodep->right; nodep = nodep->right)
;
return (struct node *) nodep;
}
/*
* No left child. Go up until node is right child of a parent.
* That parent is then the next node.
*/
while (nodep->parent && nodep == nodep->parent->left)
nodep = nodep->parent;
return (struct node *) nodep->parent;
}
/* Allocates space to hold a copy of the node sub-tree pointed to by
* subtree and duplicates the bit settings to the newly allocated nodes.
* Returns the newly allocated copy of subtree.
*/
static struct node *node_copy_subtree(const struct node *subtree)
{
struct node *root;
/* Duplicate the node at the root of the subtree */
root = calloc(1, sizeof(*root));
if (!root) {
perror("calloc");
abort();
}
root->idx = subtree->idx;
root->mask = subtree->mask;
root->num_after = subtree->num_after;
/* As needed, recursively duplicate the left and right subtrees */
if (subtree->left) {
root->left = node_copy_subtree(subtree->left);
root->left->parent = root;
}
if (subtree->right) {
root->right = node_copy_subtree(subtree->right);
root->right->parent = root;
}
return root;
}
/* Searches for and returns a pointer to the node that describes the setting
* of the bit given by idx. A node describes the setting of a bit if its
* index is within the bits described by the mask bits or the number of
* contiguous bits set after the mask. Returns NULL if there is no such node.
*/
static struct node *node_find(const struct sparsebit *s, sparsebit_idx_t idx)
{
struct node *nodep;
/* Find the node that describes the setting of the bit at idx */
for (nodep = s->root; nodep;
nodep = nodep->idx > idx ? nodep->left : nodep->right) {
if (idx >= nodep->idx &&
idx <= nodep->idx + MASK_BITS + nodep->num_after - 1)
break;
}
return nodep;
}
/* Entry Requirements:
* + A node that describes the setting of idx is not already present.
*
* Adds a new node to describe the setting of the bit at the index given
* by idx. Returns a pointer to the newly added node.
*
* TODO(lhuemill): Degenerate cases causes the tree to get unbalanced.
*/
static struct node *node_add(struct sparsebit *s, sparsebit_idx_t idx)
{
struct node *nodep, *parentp, *prev;
/* Allocate and initialize the new node. */
nodep = calloc(1, sizeof(*nodep));
if (!nodep) {
perror("calloc");
abort();
}
nodep->idx = idx & -MASK_BITS;
/* If no nodes, set it up as the root node. */
if (!s->root) {
s->root = nodep;
return nodep;
}
/*
* Find the parent where the new node should be attached
* and add the node there.
*/
parentp = s->root;
while (true) {
if (idx < parentp->idx) {
if (!parentp->left) {
parentp->left = nodep;
nodep->parent = parentp;
break;
}
parentp = parentp->left;
} else {
assert(idx > parentp->idx + MASK_BITS + parentp->num_after - 1);
if (!parentp->right) {
parentp->right = nodep;
nodep->parent = parentp;
break;
}
parentp = parentp->right;
}
}
/*
* Does num_after bits of previous node overlap with the mask
* of the new node? If so set the bits in the new nodes mask
* and reduce the previous nodes num_after.
*/
prev = node_prev(s, nodep);
while (prev && prev->idx + MASK_BITS + prev->num_after - 1 >= nodep->idx) {
unsigned int n1 = (prev->idx + MASK_BITS + prev->num_after - 1)
- nodep->idx;
assert(prev->num_after > 0);
assert(n1 < MASK_BITS);
assert(!(nodep->mask & (1 << n1)));
nodep->mask |= (1 << n1);
prev->num_after--;
}
return nodep;
}
/* Returns whether all the bits in the sparsebit array are set. */
bool sparsebit_all_set(const struct sparsebit *s)
{
/*
* If any nodes there must be at least one bit set. Only case
* where a bit is set and total num set is 0, is when all bits
* are set.
*/
return s->root && s->num_set == 0;
}
/* Clears all bits described by the node pointed to by nodep, then
* removes the node.
*/
static void node_rm(struct sparsebit *s, struct node *nodep)
{
struct node *tmp;
sparsebit_num_t num_set;
num_set = node_num_set(nodep);
assert(s->num_set >= num_set || sparsebit_all_set(s));
s->num_set -= node_num_set(nodep);
/* Have both left and right child */
if (nodep->left && nodep->right) {
/*
* Move left children to the leftmost leaf node
* of the right child.
*/
for (tmp = nodep->right; tmp->left; tmp = tmp->left)
;
tmp->left = nodep->left;
nodep->left = NULL;
tmp->left->parent = tmp;
}
/* Left only child */
if (nodep->left) {
if (!nodep->parent) {
s->root = nodep->left;
nodep->left->parent = NULL;
} else {
nodep->left->parent = nodep->parent;
if (nodep == nodep->parent->left)
nodep->parent->left = nodep->left;
else {
assert(nodep == nodep->parent->right);
nodep->parent->right = nodep->left;
}
}
nodep->parent = nodep->left = nodep->right = NULL;
free(nodep);
return;
}
/* Right only child */
if (nodep->right) {
if (!nodep->parent) {
s->root = nodep->right;
nodep->right->parent = NULL;
} else {
nodep->right->parent = nodep->parent;
if (nodep == nodep->parent->left)
nodep->parent->left = nodep->right;
else {
assert(nodep == nodep->parent->right);
nodep->parent->right = nodep->right;
}
}
nodep->parent = nodep->left = nodep->right = NULL;
free(nodep);
return;
}
/* Leaf Node */
if (!nodep->parent) {
s->root = NULL;
} else {
if (nodep->parent->left == nodep)
nodep->parent->left = NULL;
else {
assert(nodep == nodep->parent->right);
nodep->parent->right = NULL;
}
}
nodep->parent = nodep->left = nodep->right = NULL;
free(nodep);
return;
}
/* Splits the node containing the bit at idx so that there is a node
* that starts at the specified index. If no such node exists, a new
* node at the specified index is created. Returns the new node.
*
* idx must start of a mask boundary.
*/
static struct node *node_split(struct sparsebit *s, sparsebit_idx_t idx)
{
struct node *nodep1, *nodep2;
sparsebit_idx_t offset;
sparsebit_num_t orig_num_after;
assert(!(idx % MASK_BITS));
/*
* Is there a node that describes the setting of idx?
* If not, add it.
*/
nodep1 = node_find(s, idx);
if (!nodep1)
return node_add(s, idx);
/*
* All done if the starting index of the node is where the
* split should occur.
*/
if (nodep1->idx == idx)
return nodep1;
/*
* Split point not at start of mask, so it must be part of
* bits described by num_after.
*/
/*
* Calculate offset within num_after for where the split is
* to occur.
*/
offset = idx - (nodep1->idx + MASK_BITS);
orig_num_after = nodep1->num_after;
/*
* Add a new node to describe the bits starting at
* the split point.
*/
nodep1->num_after = offset;
nodep2 = node_add(s, idx);
/* Move bits after the split point into the new node */
nodep2->num_after = orig_num_after - offset;
if (nodep2->num_after >= MASK_BITS) {
nodep2->mask = ~(mask_t) 0;
nodep2->num_after -= MASK_BITS;
} else {
nodep2->mask = (1 << nodep2->num_after) - 1;
nodep2->num_after = 0;
}
return nodep2;
}
/* Iteratively reduces the node pointed to by nodep and its adjacent
* nodes into a more compact form. For example, a node with a mask with
* all bits set adjacent to a previous node, will get combined into a
* single node with an increased num_after setting.
*
* After each reduction, a further check is made to see if additional
* reductions are possible with the new previous and next nodes. Note,
* a search for a reduction is only done across the nodes nearest nodep
* and those that became part of a reduction. Reductions beyond nodep
* and the adjacent nodes that are reduced are not discovered. It is the
* responsibility of the caller to pass a nodep that is within one node
* of each possible reduction.
*
* This function does not fix the temporary violation of all invariants.
* For example it does not fix the case where the bit settings described
* by two or more nodes overlap. Such a violation introduces the potential
* complication of a bit setting for a specific index having different settings
* in different nodes. This would then introduce the further complication
* of which node has the correct setting of the bit and thus such conditions
* are not allowed.
*
* This function is designed to fix invariant violations that are introduced
* by node_split() and by changes to the nodes mask or num_after members.
* For example, when setting a bit within a nodes mask, the function that
* sets the bit doesn't have to worry about whether the setting of that
* bit caused the mask to have leading only or trailing only bits set.
* Instead, the function can call node_reduce(), with nodep equal to the
* node address that it set a mask bit in, and node_reduce() will notice
* the cases of leading or trailing only bits and that there is an
* adjacent node that the bit settings could be merged into.
*
* This implementation specifically detects and corrects violation of the
* following invariants:
*
* + Node are only used to represent bits that are set.
* Nodes with a mask of 0 and num_after of 0 are not allowed.
*
* + The setting of at least one bit is always described in a nodes
* mask (mask >= 1).
*
* + A node with all mask bits set only occurs when the last bit
* described by the previous node is not equal to this nodes
* starting index - 1. All such occurences of this condition are
* avoided by moving the setting of the nodes mask bits into
* the previous nodes num_after setting.
*/
static void node_reduce(struct sparsebit *s, struct node *nodep)
{
bool reduction_performed;
do {
reduction_performed = false;
struct node *prev, *next, *tmp;
/* 1) Potential reductions within the current node. */
/* Nodes with all bits cleared may be removed. */
if (nodep->mask == 0 && nodep->num_after == 0) {
/*
* About to remove the node pointed to by
* nodep, which normally would cause a problem
* for the next pass through the reduction loop,
* because the node at the starting point no longer
* exists. This potential problem is handled
* by first remembering the location of the next
* or previous nodes. Doesn't matter which, because
* once the node at nodep is removed, there will be
* no other nodes between prev and next.
*
* Note, the checks performed on nodep against both
* both prev and next both check for an adjacent
* node that can be reduced into a single node. As
* such, after removing the node at nodep, doesn't
* matter whether the nodep for the next pass
* through the loop is equal to the previous pass
* prev or next node. Either way, on the next pass
* the one not selected will become either the
* prev or next node.
*/
tmp = node_next(s, nodep);
if (!tmp)
tmp = node_prev(s, nodep);
node_rm(s, nodep);
nodep = tmp;
reduction_performed = true;
continue;
}
/*
* When the mask is 0, can reduce the amount of num_after
* bits by moving the initial num_after bits into the mask.
*/
if (nodep->mask == 0) {
assert(nodep->num_after != 0);
assert(nodep->idx + MASK_BITS > nodep->idx);
nodep->idx += MASK_BITS;
if (nodep->num_after >= MASK_BITS) {
nodep->mask = ~0;
nodep->num_after -= MASK_BITS;
} else {
nodep->mask = (1u << nodep->num_after) - 1;
nodep->num_after = 0;
}
reduction_performed = true;
continue;
}
/*
* 2) Potential reductions between the current and
* previous nodes.
*/
prev = node_prev(s, nodep);
if (prev) {
sparsebit_idx_t prev_highest_bit;
/* Nodes with no bits set can be removed. */
if (prev->mask == 0 && prev->num_after == 0) {
node_rm(s, prev);
reduction_performed = true;
continue;
}
/*
* All mask bits set and previous node has
* adjacent index.
*/
if (nodep->mask + 1 == 0 &&
prev->idx + MASK_BITS == nodep->idx) {
prev->num_after += MASK_BITS + nodep->num_after;
nodep->mask = 0;
nodep->num_after = 0;
reduction_performed = true;
continue;
}
/*
* Is node adjacent to previous node and the node
* contains a single contiguous range of bits
* starting from the beginning of the mask?
*/
prev_highest_bit = prev->idx + MASK_BITS - 1 + prev->num_after;
if (prev_highest_bit + 1 == nodep->idx &&
(nodep->mask | (nodep->mask >> 1)) == nodep->mask) {
/*
* How many contiguous bits are there?
* Is equal to the total number of set
* bits, due to an earlier check that
* there is a single contiguous range of
* set bits.
*/
unsigned int num_contiguous
= __builtin_popcount(nodep->mask);
assert((num_contiguous > 0) &&
((1ULL << num_contiguous) - 1) == nodep->mask);
prev->num_after += num_contiguous;
nodep->mask = 0;
/*
* For predictable performance, handle special
* case where all mask bits are set and there
* is a non-zero num_after setting. This code
* is functionally correct without the following
* conditionalized statements, but without them
* the value of num_after is only reduced by
* the number of mask bits per pass. There are
* cases where num_after can be close to 2^64.
* Without this code it could take nearly
* (2^64) / 32 passes to perform the full
* reduction.
*/
if (num_contiguous == MASK_BITS) {
prev->num_after += nodep->num_after;
nodep->num_after = 0;
}
reduction_performed = true;
continue;
}
}
/*
* 3) Potential reductions between the current and
* next nodes.
*/
next = node_next(s, nodep);
if (next) {
/* Nodes with no bits set can be removed. */
if (next->mask == 0 && next->num_after == 0) {
node_rm(s, next);
reduction_performed = true;
continue;
}
/*
* Is next node index adjacent to current node
* and has a mask with all bits set?
*/
if (next->idx == nodep->idx + MASK_BITS + nodep->num_after &&
next->mask == ~(mask_t) 0) {
nodep->num_after += MASK_BITS;
next->mask = 0;
nodep->num_after += next->num_after;
next->num_after = 0;
node_rm(s, next);
next = NULL;
reduction_performed = true;
continue;
}
}
} while (nodep && reduction_performed);
}
/* Returns whether the bit at the index given by idx, within the
* sparsebit array is set or not.
*/
bool sparsebit_is_set(const struct sparsebit *s, sparsebit_idx_t idx)
{
struct node *nodep;
/* Find the node that describes the setting of the bit at idx */
for (nodep = s->root; nodep;
nodep = nodep->idx > idx ? nodep->left : nodep->right)
if (idx >= nodep->idx &&
idx <= nodep->idx + MASK_BITS + nodep->num_after - 1)
goto have_node;
return false;
have_node:
/* Bit is set if it is any of the bits described by num_after */
if (nodep->num_after && idx >= nodep->idx + MASK_BITS)
return true;
/* Is the corresponding mask bit set */
assert(idx >= nodep->idx && idx - nodep->idx < MASK_BITS);
return !!(nodep->mask & (1 << (idx - nodep->idx)));
}
/* Within the sparsebit array pointed to by s, sets the bit
* at the index given by idx.
*/
static void bit_set(struct sparsebit *s, sparsebit_idx_t idx)
{
struct node *nodep;
/* Skip bits that are already set */
if (sparsebit_is_set(s, idx))
return;
/*
* Get a node where the bit at idx is described by the mask.
* The node_split will also create a node, if there isn't
* already a node that describes the setting of bit.
*/
nodep = node_split(s, idx & -MASK_BITS);
/* Set the bit within the nodes mask */
assert(idx >= nodep->idx && idx <= nodep->idx + MASK_BITS - 1);
assert(!(nodep->mask & (1 << (idx - nodep->idx))));
nodep->mask |= 1 << (idx - nodep->idx);
s->num_set++;
node_reduce(s, nodep);
}
/* Within the sparsebit array pointed to by s, clears the bit
* at the index given by idx.
*/
static void bit_clear(struct sparsebit *s, sparsebit_idx_t idx)
{
struct node *nodep;
/* Skip bits that are already cleared */
if (!sparsebit_is_set(s, idx))
return;
/* Is there a node that describes the setting of this bit? */
nodep = node_find(s, idx);
if (!nodep)
return;
/*
* If a num_after bit, split the node, so that the bit is
* part of a node mask.
*/
if (idx >= nodep->idx + MASK_BITS)
nodep = node_split(s, idx & -MASK_BITS);
/*
* After node_split above, bit at idx should be within the mask.
* Clear that bit.
*/
assert(idx >= nodep->idx && idx <= nodep->idx + MASK_BITS - 1);
assert(nodep->mask & (1 << (idx - nodep->idx)));
nodep->mask &= ~(1 << (idx - nodep->idx));
assert(s->num_set > 0 || sparsebit_all_set(s));
s->num_set--;
node_reduce(s, nodep);
}
/* Recursively dumps to the FILE stream given by stream the contents
* of the sub-tree of nodes pointed to by nodep. Each line of output
* is prefixed by the number of spaces given by indent. On each
* recursion, the indent amount is increased by 2. This causes nodes
* at each level deeper into the binary search tree to be displayed
* with a greater indent.
*/
static void dump_nodes(FILE *stream, struct node *nodep,
unsigned int indent)
{
char *node_type;
/* Dump contents of node */
if (!nodep->parent)
node_type = "root";
else if (nodep == nodep->parent->left)
node_type = "left";
else {
assert(nodep == nodep->parent->right);
node_type = "right";
}
fprintf(stream, "%*s---- %s nodep: %p\n", indent, "", node_type, nodep);
fprintf(stream, "%*s parent: %p left: %p right: %p\n", indent, "",
nodep->parent, nodep->left, nodep->right);
fprintf(stream, "%*s idx: 0x%lx mask: 0x%x num_after: 0x%lx\n",
indent, "", nodep->idx, nodep->mask, nodep->num_after);
/* If present, dump contents of left child nodes */
if (nodep->left)
dump_nodes(stream, nodep->left, indent + 2);
/* If present, dump contents of right child nodes */
if (nodep->right)
dump_nodes(stream, nodep->right, indent + 2);
}
static inline sparsebit_idx_t node_first_set(struct node *nodep, int start)
{
mask_t leading = (mask_t)1 << start;
int n1 = __builtin_ctz(nodep->mask & -leading);
return nodep->idx + n1;
}
static inline sparsebit_idx_t node_first_clear(struct node *nodep, int start)
{
mask_t leading = (mask_t)1 << start;
int n1 = __builtin_ctz(~nodep->mask & -leading);
return nodep->idx + n1;
}
/* Dumps to the FILE stream specified by stream, the implementation dependent
* internal state of s. Each line of output is prefixed with the number
* of spaces given by indent. The output is completely implementation
* dependent and subject to change. Output from this function should only
* be used for diagnostic purposes. For example, this function can be
* used by test cases after they detect an unexpected condition, as a means
* to capture diagnostic information.
*/
static void sparsebit_dump_internal(FILE *stream, const struct sparsebit *s,
unsigned int indent)
{
/* Dump the contents of s */
fprintf(stream, "%*sroot: %p\n", indent, "", s->root);
fprintf(stream, "%*snum_set: 0x%lx\n", indent, "", s->num_set);
if (s->root)
dump_nodes(stream, s->root, indent);
}
/* Allocates and returns a new sparsebit array. The initial state
* of the newly allocated sparsebit array has all bits cleared.
*/
struct sparsebit *sparsebit_alloc(void)
{
struct sparsebit *s;
/* Allocate top level structure. */
s = calloc(1, sizeof(*s));
if (!s) {
perror("calloc");
abort();
}
return s;
}
/* Frees the implementation dependent data for the sparsebit array
* pointed to by s and poisons the pointer to that data.
*/
void sparsebit_free(struct sparsebit **sbitp)
{
struct sparsebit *s = *sbitp;
if (!s)
return;
sparsebit_clear_all(s);
free(s);
*sbitp = NULL;
}
/* Makes a copy of the sparsebit array given by s, to the sparsebit
* array given by d. Note, d must have already been allocated via
* sparsebit_alloc(). It can though already have bits set, which
* if different from src will be cleared.
*/
void sparsebit_copy(struct sparsebit *d, const struct sparsebit *s)
{
/* First clear any bits already set in the destination */
sparsebit_clear_all(d);
if (s->root) {
d->root = node_copy_subtree(s->root);
d->num_set = s->num_set;
}
}
/* Returns whether num consecutive bits starting at idx are all set. */
bool sparsebit_is_set_num(const struct sparsebit *s,
sparsebit_idx_t idx, sparsebit_num_t num)
{
sparsebit_idx_t next_cleared;
assert(num > 0);
assert(idx + num - 1 >= idx);
/* With num > 0, the first bit must be set. */
if (!sparsebit_is_set(s, idx))
return false;
/* Find the next cleared bit */
next_cleared = sparsebit_next_clear(s, idx);
/*
* If no cleared bits beyond idx, then there are at least num
* set bits. idx + num doesn't wrap. Otherwise check if
* there are enough set bits between idx and the next cleared bit.
*/
return next_cleared == 0 || next_cleared - idx >= num;
}
/* Returns whether the bit at the index given by idx. */
bool sparsebit_is_clear(const struct sparsebit *s,
sparsebit_idx_t idx)
{
return !sparsebit_is_set(s, idx);
}
/* Returns whether num consecutive bits starting at idx are all cleared. */
bool sparsebit_is_clear_num(const struct sparsebit *s,
sparsebit_idx_t idx, sparsebit_num_t num)
{
sparsebit_idx_t next_set;
assert(num > 0);
assert(idx + num - 1 >= idx);
/* With num > 0, the first bit must be cleared. */
if (!sparsebit_is_clear(s, idx))
return false;
/* Find the next set bit */
next_set = sparsebit_next_set(s, idx);
/*
* If no set bits beyond idx, then there are at least num
* cleared bits. idx + num doesn't wrap. Otherwise check if
* there are enough cleared bits between idx and the next set bit.
*/
return next_set == 0 || next_set - idx >= num;
}
/* Returns the total number of bits set. Note: 0 is also returned for
* the case of all bits set. This is because with all bits set, there
* is 1 additional bit set beyond what can be represented in the return
* value. Use sparsebit_any_set(), instead of sparsebit_num_set() > 0,
* to determine if the sparsebit array has any bits set.
*/
sparsebit_num_t sparsebit_num_set(const struct sparsebit *s)
{
return s->num_set;
}
/* Returns whether any bit is set in the sparsebit array. */
bool sparsebit_any_set(const struct sparsebit *s)
{
/*
* Nodes only describe set bits. If any nodes then there
* is at least 1 bit set.
*/
if (!s->root)
return false;
/*
* Every node should have a non-zero mask. For now will
* just assure that the root node has a non-zero mask,
* which is a quick check that at least 1 bit is set.
*/
assert(s->root->mask != 0);
assert(s->num_set > 0 ||
(s->root->num_after == ((sparsebit_num_t) 0) - MASK_BITS &&
s->root->mask == ~(mask_t) 0));
return true;
}
/* Returns whether all the bits in the sparsebit array are cleared. */
bool sparsebit_all_clear(const struct sparsebit *s)
{
return !sparsebit_any_set(s);
}
/* Returns whether all the bits in the sparsebit array are set. */
bool sparsebit_any_clear(const struct sparsebit *s)
{
return !sparsebit_all_set(s);
}
/* Returns the index of the first set bit. Abort if no bits are set.
*/
sparsebit_idx_t sparsebit_first_set(const struct sparsebit *s)
{
struct node *nodep;
/* Validate at least 1 bit is set */
assert(sparsebit_any_set(s));
nodep = node_first(s);
return node_first_set(nodep, 0);
}
/* Returns the index of the first cleared bit. Abort if
* no bits are cleared.
*/
sparsebit_idx_t sparsebit_first_clear(const struct sparsebit *s)
{
struct node *nodep1, *nodep2;
/* Validate at least 1 bit is cleared. */
assert(sparsebit_any_clear(s));
/* If no nodes or first node index > 0 then lowest cleared is 0 */
nodep1 = node_first(s);
if (!nodep1 || nodep1->idx > 0)
return 0;
/* Does the mask in the first node contain any cleared bits. */
if (nodep1->mask != ~(mask_t) 0)
return node_first_clear(nodep1, 0);
/*
* All mask bits set in first node. If there isn't a second node
* then the first cleared bit is the first bit after the bits
* described by the first node.
*/
nodep2 = node_next(s, nodep1);
if (!nodep2) {
/*
* No second node. First cleared bit is first bit beyond
* bits described by first node.
*/
assert(nodep1->mask == ~(mask_t) 0);
assert(nodep1->idx + MASK_BITS + nodep1->num_after != (sparsebit_idx_t) 0);
return nodep1->idx + MASK_BITS + nodep1->num_after;
}
/*
* There is a second node.
* If it is not adjacent to the first node, then there is a gap
* of cleared bits between the nodes, and the first cleared bit
* is the first bit within the gap.
*/
if (nodep1->idx + MASK_BITS + nodep1->num_after != nodep2->idx)
return nodep1->idx + MASK_BITS + nodep1->num_after;
/*
* Second node is adjacent to the first node.
* Because it is adjacent, its mask should be non-zero. If all
* its mask bits are set, then with it being adjacent, it should
* have had the mask bits moved into the num_after setting of the
* previous node.
*/
return node_first_clear(nodep2, 0);
}
/* Returns index of next bit set within s after the index given by prev.
* Returns 0 if there are no bits after prev that are set.
*/
sparsebit_idx_t sparsebit_next_set(const struct sparsebit *s,
sparsebit_idx_t prev)
{
sparsebit_idx_t lowest_possible = prev + 1;
sparsebit_idx_t start;
struct node *nodep;
/* A bit after the highest index can't be set. */
if (lowest_possible == 0)
return 0;
/*
* Find the leftmost 'candidate' overlapping or to the right
* of lowest_possible.
*/
struct node *candidate = NULL;
/* True iff lowest_possible is within candidate */
bool contains = false;
/*
* Find node that describes setting of bit at lowest_possible.
* If such a node doesn't exist, find the node with the lowest
* starting index that is > lowest_possible.
*/
for (nodep = s->root; nodep;) {
if ((nodep->idx + MASK_BITS + nodep->num_after - 1)
>= lowest_possible) {
candidate = nodep;
if (candidate->idx <= lowest_possible) {
contains = true;
break;
}
nodep = nodep->left;
} else {
nodep = nodep->right;
}
}
if (!candidate)
return 0;
assert(candidate->mask != 0);
/* Does the candidate node describe the setting of lowest_possible? */
if (!contains) {
/*
* Candidate doesn't describe setting of bit at lowest_possible.
* Candidate points to the first node with a starting index
* > lowest_possible.
*/
assert(candidate->idx > lowest_possible);
return node_first_set(candidate, 0);
}
/*
* Candidate describes setting of bit at lowest_possible.
* Note: although the node describes the setting of the bit
* at lowest_possible, its possible that its setting and the
* setting of all latter bits described by this node are 0.
* For now, just handle the cases where this node describes
* a bit at or after an index of lowest_possible that is set.
*/
start = lowest_possible - candidate->idx;
if (start < MASK_BITS && candidate->mask >= (1 << start))
return node_first_set(candidate, start);
if (candidate->num_after) {
sparsebit_idx_t first_num_after_idx = candidate->idx + MASK_BITS;
return lowest_possible < first_num_after_idx
? first_num_after_idx : lowest_possible;
}
/*
* Although candidate node describes setting of bit at
* the index of lowest_possible, all bits at that index and
* latter that are described by candidate are cleared. With
* this, the next bit is the first bit in the next node, if
* such a node exists. If a next node doesn't exist, then
* there is no next set bit.
*/
candidate = node_next(s, candidate);
if (!candidate)
return 0;
return node_first_set(candidate, 0);
}
/* Returns index of next bit cleared within s after the index given by prev.
* Returns 0 if there are no bits after prev that are cleared.
*/
sparsebit_idx_t sparsebit_next_clear(const struct sparsebit *s,
sparsebit_idx_t prev)
{
sparsebit_idx_t lowest_possible = prev + 1;
sparsebit_idx_t idx;
struct node *nodep1, *nodep2;
/* A bit after the highest index can't be set. */
if (lowest_possible == 0)
return 0;
/*
* Does a node describing the setting of lowest_possible exist?
* If not, the bit at lowest_possible is cleared.
*/
nodep1 = node_find(s, lowest_possible);
if (!nodep1)
return lowest_possible;
/* Does a mask bit in node 1 describe the next cleared bit. */
for (idx = lowest_possible - nodep1->idx; idx < MASK_BITS; idx++)
if (!(nodep1->mask & (1 << idx)))
return nodep1->idx + idx;
/*
* Next cleared bit is not described by node 1. If there
* isn't a next node, then next cleared bit is described
* by bit after the bits described by the first node.
*/
nodep2 = node_next(s, nodep1);
if (!nodep2)
return nodep1->idx + MASK_BITS + nodep1->num_after;
/*
* There is a second node.
* If it is not adjacent to the first node, then there is a gap
* of cleared bits between the nodes, and the next cleared bit
* is the first bit within the gap.
*/
if (nodep1->idx + MASK_BITS + nodep1->num_after != nodep2->idx)
return nodep1->idx + MASK_BITS + nodep1->num_after;
/*
* Second node is adjacent to the first node.
* Because it is adjacent, its mask should be non-zero. If all
* its mask bits are set, then with it being adjacent, it should
* have had the mask bits moved into the num_after setting of the
* previous node.
*/
return node_first_clear(nodep2, 0);
}
/* Starting with the index 1 greater than the index given by start, finds
* and returns the index of the first sequence of num consecutively set
* bits. Returns a value of 0 of no such sequence exists.
*/
sparsebit_idx_t sparsebit_next_set_num(const struct sparsebit *s,
sparsebit_idx_t start, sparsebit_num_t num)
{
sparsebit_idx_t idx;
assert(num >= 1);
for (idx = sparsebit_next_set(s, start);
idx != 0 && idx + num - 1 >= idx;
idx = sparsebit_next_set(s, idx)) {
assert(sparsebit_is_set(s, idx));
/*
* Does the sequence of bits starting at idx consist of
* num set bits?
*/
if (sparsebit_is_set_num(s, idx, num))
return idx;
/*
* Sequence of set bits at idx isn't large enough.
* Skip this entire sequence of set bits.
*/
idx = sparsebit_next_clear(s, idx);
if (idx == 0)
return 0;
}
return 0;
}
/* Starting with the index 1 greater than the index given by start, finds
* and returns the index of the first sequence of num consecutively cleared
* bits. Returns a value of 0 of no such sequence exists.
*/
sparsebit_idx_t sparsebit_next_clear_num(const struct sparsebit *s,
sparsebit_idx_t start, sparsebit_num_t num)
{
sparsebit_idx_t idx;
assert(num >= 1);
for (idx = sparsebit_next_clear(s, start);
idx != 0 && idx + num - 1 >= idx;
idx = sparsebit_next_clear(s, idx)) {
assert(sparsebit_is_clear(s, idx));
/*
* Does the sequence of bits starting at idx consist of
* num cleared bits?
*/
if (sparsebit_is_clear_num(s, idx, num))
return idx;
/*
* Sequence of cleared bits at idx isn't large enough.
* Skip this entire sequence of cleared bits.
*/
idx = sparsebit_next_set(s, idx);
if (idx == 0)
return 0;
}
return 0;
}
/* Sets the bits * in the inclusive range idx through idx + num - 1. */
void sparsebit_set_num(struct sparsebit *s,
sparsebit_idx_t start, sparsebit_num_t num)
{
struct node *nodep, *next;
unsigned int n1;
sparsebit_idx_t idx;
sparsebit_num_t n;
sparsebit_idx_t middle_start, middle_end;
assert(num > 0);
assert(start + num - 1 >= start);
/*
* Leading - bits before first mask boundary.
*
* TODO(lhuemill): With some effort it may be possible to
* replace the following loop with a sequential sequence
* of statements. High level sequence would be:
*
* 1. Use node_split() to force node that describes setting
* of idx to be within the mask portion of a node.
* 2. Form mask of bits to be set.
* 3. Determine number of mask bits already set in the node
* and store in a local variable named num_already_set.
* 4. Set the appropriate mask bits within the node.
* 5. Increment struct sparsebit_pvt num_set member
* by the number of bits that were actually set.
* Exclude from the counts bits that were already set.
* 6. Before returning to the caller, use node_reduce() to
* handle the multiple corner cases that this method
* introduces.
*/
for (idx = start, n = num; n > 0 && idx % MASK_BITS != 0; idx++, n--)
bit_set(s, idx);
/* Middle - bits spanning one or more entire mask */
middle_start = idx;
middle_end = middle_start + (n & -MASK_BITS) - 1;
if (n >= MASK_BITS) {
nodep = node_split(s, middle_start);
/*
* As needed, split just after end of middle bits.
* No split needed if end of middle bits is at highest
* supported bit index.
*/
if (middle_end + 1 > middle_end)
(void) node_split(s, middle_end + 1);
/* Delete nodes that only describe bits within the middle. */
for (next = node_next(s, nodep);
next && (next->idx < middle_end);
next = node_next(s, nodep)) {
assert(next->idx + MASK_BITS + next->num_after - 1 <= middle_end);
node_rm(s, next);
next = NULL;
}
/* As needed set each of the mask bits */
for (n1 = 0; n1 < MASK_BITS; n1++) {
if (!(nodep->mask & (1 << n1))) {
nodep->mask |= 1 << n1;
s->num_set++;
}
}
s->num_set -= nodep->num_after;
nodep->num_after = middle_end - middle_start + 1 - MASK_BITS;
s->num_set += nodep->num_after;
node_reduce(s, nodep);
}
idx = middle_end + 1;
n -= middle_end - middle_start + 1;
/* Trailing - bits at and beyond last mask boundary */
assert(n < MASK_BITS);
for (; n > 0; idx++, n--)
bit_set(s, idx);
}
/* Clears the bits * in the inclusive range idx through idx + num - 1. */
void sparsebit_clear_num(struct sparsebit *s,
sparsebit_idx_t start, sparsebit_num_t num)
{
struct node *nodep, *next;
unsigned int n1;
sparsebit_idx_t idx;
sparsebit_num_t n;
sparsebit_idx_t middle_start, middle_end;
assert(num > 0);
assert(start + num - 1 >= start);
/* Leading - bits before first mask boundary */
for (idx = start, n = num; n > 0 && idx % MASK_BITS != 0; idx++, n--)
bit_clear(s, idx);
/* Middle - bits spanning one or more entire mask */
middle_start = idx;
middle_end = middle_start + (n & -MASK_BITS) - 1;
if (n >= MASK_BITS) {
nodep = node_split(s, middle_start);
/*
* As needed, split just after end of middle bits.
* No split needed if end of middle bits is at highest
* supported bit index.
*/
if (middle_end + 1 > middle_end)
(void) node_split(s, middle_end + 1);
/* Delete nodes that only describe bits within the middle. */
for (next = node_next(s, nodep);
next && (next->idx < middle_end);
next = node_next(s, nodep)) {
assert(next->idx + MASK_BITS + next->num_after - 1 <= middle_end);
node_rm(s, next);
next = NULL;
}
/* As needed clear each of the mask bits */
for (n1 = 0; n1 < MASK_BITS; n1++) {
if (nodep->mask & (1 << n1)) {
nodep->mask &= ~(1 << n1);
s->num_set--;
}
}
/* Clear any bits described by num_after */
s->num_set -= nodep->num_after;
nodep->num_after = 0;
/*
* Delete the node that describes the beginning of
* the middle bits and perform any allowed reductions
* with the nodes prev or next of nodep.
*/
node_reduce(s, nodep);
nodep = NULL;
}
idx = middle_end + 1;
n -= middle_end - middle_start + 1;
/* Trailing - bits at and beyond last mask boundary */
assert(n < MASK_BITS);
for (; n > 0; idx++, n--)
bit_clear(s, idx);
}
/* Sets the bit at the index given by idx. */
void sparsebit_set(struct sparsebit *s, sparsebit_idx_t idx)
{
sparsebit_set_num(s, idx, 1);
}
/* Clears the bit at the index given by idx. */
void sparsebit_clear(struct sparsebit *s, sparsebit_idx_t idx)
{
sparsebit_clear_num(s, idx, 1);
}
/* Sets the bits in the entire addressable range of the sparsebit array. */
void sparsebit_set_all(struct sparsebit *s)
{
sparsebit_set(s, 0);
sparsebit_set_num(s, 1, ~(sparsebit_idx_t) 0);
assert(sparsebit_all_set(s));
}
/* Clears the bits in the entire addressable range of the sparsebit array. */
void sparsebit_clear_all(struct sparsebit *s)
{
sparsebit_clear(s, 0);
sparsebit_clear_num(s, 1, ~(sparsebit_idx_t) 0);
assert(!sparsebit_any_set(s));
}
static size_t display_range(FILE *stream, sparsebit_idx_t low,
sparsebit_idx_t high, bool prepend_comma_space)
{
char *fmt_str;
size_t sz;
/* Determine the printf format string */
if (low == high)
fmt_str = prepend_comma_space ? ", 0x%lx" : "0x%lx";
else
fmt_str = prepend_comma_space ? ", 0x%lx:0x%lx" : "0x%lx:0x%lx";
/*
* When stream is NULL, just determine the size of what would
* have been printed, else print the range.
*/
if (!stream)
sz = snprintf(NULL, 0, fmt_str, low, high);
else
sz = fprintf(stream, fmt_str, low, high);
return sz;
}
/* Dumps to the FILE stream given by stream, the bit settings
* of s. Each line of output is prefixed with the number of
* spaces given by indent. The length of each line is implementation
* dependent and does not depend on the indent amount. The following
* is an example output of a sparsebit array that has bits:
*
* 0x5, 0x8, 0xa:0xe, 0x12
*
* This corresponds to a sparsebit whose bits 5, 8, 10, 11, 12, 13, 14, 18
* are set. Note that a ':', instead of a '-' is used to specify a range of
* contiguous bits. This is done because '-' is used to specify command-line
* options, and sometimes ranges are specified as command-line arguments.
*/
void sparsebit_dump(FILE *stream, const struct sparsebit *s,
unsigned int indent)
{
size_t current_line_len = 0;
size_t sz;
struct node *nodep;
if (!sparsebit_any_set(s))
return;
/* Display initial indent */
fprintf(stream, "%*s", indent, "");
/* For each node */
for (nodep = node_first(s); nodep; nodep = node_next(s, nodep)) {
unsigned int n1;
sparsebit_idx_t low, high;
/* For each group of bits in the mask */
for (n1 = 0; n1 < MASK_BITS; n1++) {
if (nodep->mask & (1 << n1)) {
low = high = nodep->idx + n1;
for (; n1 < MASK_BITS; n1++) {
if (nodep->mask & (1 << n1))
high = nodep->idx + n1;
else
break;
}
if ((n1 == MASK_BITS) && nodep->num_after)
high += nodep->num_after;
/*
* How much room will it take to display
* this range.
*/
sz = display_range(NULL, low, high,
current_line_len != 0);
/*
* If there is not enough room, display
* a newline plus the indent of the next
* line.
*/
if (current_line_len + sz > DUMP_LINE_MAX) {
fputs("\n", stream);
fprintf(stream, "%*s", indent, "");
current_line_len = 0;
}
/* Display the range */
sz = display_range(stream, low, high,
current_line_len != 0);
current_line_len += sz;
}
}
/*
* If num_after and most significant-bit of mask is not
* set, then still need to display a range for the bits
* described by num_after.
*/
if (!(nodep->mask & (1 << (MASK_BITS - 1))) && nodep->num_after) {
low = nodep->idx + MASK_BITS;
high = nodep->idx + MASK_BITS + nodep->num_after - 1;
/*
* How much room will it take to display
* this range.
*/
sz = display_range(NULL, low, high,
current_line_len != 0);
/*
* If there is not enough room, display
* a newline plus the indent of the next
* line.
*/
if (current_line_len + sz > DUMP_LINE_MAX) {
fputs("\n", stream);
fprintf(stream, "%*s", indent, "");
current_line_len = 0;
}
/* Display the range */
sz = display_range(stream, low, high,
current_line_len != 0);
current_line_len += sz;
}
}
fputs("\n", stream);
}
/* Validates the internal state of the sparsebit array given by
* s. On error, diagnostic information is printed to stderr and
* abort is called.
*/
void sparsebit_validate_internal(const struct sparsebit *s)
{
bool error_detected = false;
struct node *nodep, *prev = NULL;
sparsebit_num_t total_bits_set = 0;
unsigned int n1;
/* For each node */
for (nodep = node_first(s); nodep;
prev = nodep, nodep = node_next(s, nodep)) {
/*
* Increase total bits set by the number of bits set
* in this node.
*/
for (n1 = 0; n1 < MASK_BITS; n1++)
if (nodep->mask & (1 << n1))
total_bits_set++;
total_bits_set += nodep->num_after;
/*
* Arbitrary choice as to whether a mask of 0 is allowed
* or not. For diagnostic purposes it is beneficial to
* have only one valid means to represent a set of bits.
* To support this an arbitrary choice has been made
* to not allow a mask of zero.
*/
if (nodep->mask == 0) {
fprintf(stderr, "Node mask of zero, "
"nodep: %p nodep->mask: 0x%x",
nodep, nodep->mask);
error_detected = true;
break;
}
/*
* Validate num_after is not greater than the max index
* - the number of mask bits. The num_after member
* uses 0-based indexing and thus has no value that
* represents all bits set. This limitation is handled
* by requiring a non-zero mask. With a non-zero mask,
* MASK_BITS worth of bits are described by the mask,
* which makes the largest needed num_after equal to:
*
* (~(sparsebit_num_t) 0) - MASK_BITS + 1
*/
if (nodep->num_after
> (~(sparsebit_num_t) 0) - MASK_BITS + 1) {
fprintf(stderr, "num_after too large, "
"nodep: %p nodep->num_after: 0x%lx",
nodep, nodep->num_after);
error_detected = true;
break;
}
/* Validate node index is divisible by the mask size */
if (nodep->idx % MASK_BITS) {
fprintf(stderr, "Node index not divisible by "
"mask size,\n"
" nodep: %p nodep->idx: 0x%lx "
"MASK_BITS: %lu\n",
nodep, nodep->idx, MASK_BITS);
error_detected = true;
break;
}
/*
* Validate bits described by node don't wrap beyond the
* highest supported index.
*/
if ((nodep->idx + MASK_BITS + nodep->num_after - 1) < nodep->idx) {
fprintf(stderr, "Bits described by node wrap "
"beyond highest supported index,\n"
" nodep: %p nodep->idx: 0x%lx\n"
" MASK_BITS: %lu nodep->num_after: 0x%lx",
nodep, nodep->idx, MASK_BITS, nodep->num_after);
error_detected = true;
break;
}
/* Check parent pointers. */
if (nodep->left) {
if (nodep->left->parent != nodep) {
fprintf(stderr, "Left child parent pointer "
"doesn't point to this node,\n"
" nodep: %p nodep->left: %p "
"nodep->left->parent: %p",
nodep, nodep->left,
nodep->left->parent);
error_detected = true;
break;
}
}
if (nodep->right) {
if (nodep->right->parent != nodep) {
fprintf(stderr, "Right child parent pointer "
"doesn't point to this node,\n"
" nodep: %p nodep->right: %p "
"nodep->right->parent: %p",
nodep, nodep->right,
nodep->right->parent);
error_detected = true;
break;
}
}
if (!nodep->parent) {
if (s->root != nodep) {
fprintf(stderr, "Unexpected root node, "
"s->root: %p nodep: %p",
s->root, nodep);
error_detected = true;
break;
}
}
if (prev) {
/*
* Is index of previous node before index of
* current node?
*/
if (prev->idx >= nodep->idx) {
fprintf(stderr, "Previous node index "
">= current node index,\n"
" prev: %p prev->idx: 0x%lx\n"
" nodep: %p nodep->idx: 0x%lx",
prev, prev->idx, nodep, nodep->idx);
error_detected = true;
break;
}
/*
* Nodes occur in asscending order, based on each
* nodes starting index.
*/
if ((prev->idx + MASK_BITS + prev->num_after - 1)
>= nodep->idx) {
fprintf(stderr, "Previous node bit range "
"overlap with current node bit range,\n"
" prev: %p prev->idx: 0x%lx "
"prev->num_after: 0x%lx\n"
" nodep: %p nodep->idx: 0x%lx "
"nodep->num_after: 0x%lx\n"
" MASK_BITS: %lu",
prev, prev->idx, prev->num_after,
nodep, nodep->idx, nodep->num_after,
MASK_BITS);
error_detected = true;
break;
}
/*
* When the node has all mask bits set, it shouldn't
* be adjacent to the last bit described by the
* previous node.
*/
if (nodep->mask == ~(mask_t) 0 &&
prev->idx + MASK_BITS + prev->num_after == nodep->idx) {
fprintf(stderr, "Current node has mask with "
"all bits set and is adjacent to the "
"previous node,\n"
" prev: %p prev->idx: 0x%lx "
"prev->num_after: 0x%lx\n"
" nodep: %p nodep->idx: 0x%lx "
"nodep->num_after: 0x%lx\n"
" MASK_BITS: %lu",
prev, prev->idx, prev->num_after,
nodep, nodep->idx, nodep->num_after,
MASK_BITS);
error_detected = true;
break;
}
}
}
if (!error_detected) {
/*
* Is sum of bits set in each node equal to the count
* of total bits set.
*/
if (s->num_set != total_bits_set) {
fprintf(stderr, "Number of bits set mismatch,\n"
" s->num_set: 0x%lx total_bits_set: 0x%lx",
s->num_set, total_bits_set);
error_detected = true;
}
}
if (error_detected) {
fputs(" dump_internal:\n", stderr);
sparsebit_dump_internal(stderr, s, 4);
abort();
}
}
#ifdef FUZZ
/* A simple but effective fuzzing driver. Look for bugs with the help
* of some invariants and of a trivial representation of sparsebit.
* Just use 512 bytes of /dev/zero and /dev/urandom as inputs, and let
* afl-fuzz do the magic. :)
*/
#include <stdlib.h>
struct range {
sparsebit_idx_t first, last;
bool set;
};
struct sparsebit *s;
struct range ranges[1000];
int num_ranges;
static bool get_value(sparsebit_idx_t idx)
{
int i;
for (i = num_ranges; --i >= 0; )
if (ranges[i].first <= idx && idx <= ranges[i].last)
return ranges[i].set;
return false;
}
static void operate(int code, sparsebit_idx_t first, sparsebit_idx_t last)
{
sparsebit_num_t num;
sparsebit_idx_t next;
if (first < last) {
num = last - first + 1;
} else {
num = first - last + 1;
first = last;
last = first + num - 1;
}
switch (code) {
case 0:
sparsebit_set(s, first);
assert(sparsebit_is_set(s, first));
assert(!sparsebit_is_clear(s, first));
assert(sparsebit_any_set(s));
assert(!sparsebit_all_clear(s));
if (get_value(first))
return;
if (num_ranges == 1000)
exit(0);
ranges[num_ranges++] = (struct range)
{ .first = first, .last = first, .set = true };
break;
case 1:
sparsebit_clear(s, first);
assert(!sparsebit_is_set(s, first));
assert(sparsebit_is_clear(s, first));
assert(sparsebit_any_clear(s));
assert(!sparsebit_all_set(s));
if (!get_value(first))
return;
if (num_ranges == 1000)
exit(0);
ranges[num_ranges++] = (struct range)
{ .first = first, .last = first, .set = false };
break;
case 2:
assert(sparsebit_is_set(s, first) == get_value(first));
assert(sparsebit_is_clear(s, first) == !get_value(first));
break;
case 3:
if (sparsebit_any_set(s))
assert(get_value(sparsebit_first_set(s)));
if (sparsebit_any_clear(s))
assert(!get_value(sparsebit_first_clear(s)));
sparsebit_set_all(s);
assert(!sparsebit_any_clear(s));
assert(sparsebit_all_set(s));
num_ranges = 0;
ranges[num_ranges++] = (struct range)
{ .first = 0, .last = ~(sparsebit_idx_t)0, .set = true };
break;
case 4:
if (sparsebit_any_set(s))
assert(get_value(sparsebit_first_set(s)));
if (sparsebit_any_clear(s))
assert(!get_value(sparsebit_first_clear(s)));
sparsebit_clear_all(s);
assert(!sparsebit_any_set(s));
assert(sparsebit_all_clear(s));
num_ranges = 0;
break;
case 5:
next = sparsebit_next_set(s, first);
assert(next == 0 || next > first);
assert(next == 0 || get_value(next));
break;
case 6:
next = sparsebit_next_clear(s, first);
assert(next == 0 || next > first);
assert(next == 0 || !get_value(next));
break;
case 7:
next = sparsebit_next_clear(s, first);
if (sparsebit_is_set_num(s, first, num)) {
assert(next == 0 || next > last);
if (first)
next = sparsebit_next_set(s, first - 1);
else if (sparsebit_any_set(s))
next = sparsebit_first_set(s);
else
return;
assert(next == first);
} else {
assert(sparsebit_is_clear(s, first) || next <= last);
}
break;
case 8:
next = sparsebit_next_set(s, first);
if (sparsebit_is_clear_num(s, first, num)) {
assert(next == 0 || next > last);
if (first)
next = sparsebit_next_clear(s, first - 1);
else if (sparsebit_any_clear(s))
next = sparsebit_first_clear(s);
else
return;
assert(next == first);
} else {
assert(sparsebit_is_set(s, first) || next <= last);
}
break;
case 9:
sparsebit_set_num(s, first, num);
assert(sparsebit_is_set_num(s, first, num));
assert(!sparsebit_is_clear_num(s, first, num));
assert(sparsebit_any_set(s));
assert(!sparsebit_all_clear(s));
if (num_ranges == 1000)
exit(0);
ranges[num_ranges++] = (struct range)
{ .first = first, .last = last, .set = true };
break;
case 10:
sparsebit_clear_num(s, first, num);
assert(!sparsebit_is_set_num(s, first, num));
assert(sparsebit_is_clear_num(s, first, num));
assert(sparsebit_any_clear(s));
assert(!sparsebit_all_set(s));
if (num_ranges == 1000)
exit(0);
ranges[num_ranges++] = (struct range)
{ .first = first, .last = last, .set = false };
break;
case 11:
sparsebit_validate_internal(s);
break;
default:
break;
}
}
unsigned char get8(void)
{
int ch;
ch = getchar();
if (ch == EOF)
exit(0);
return ch;
}
uint64_t get64(void)
{
uint64_t x;
x = get8();
x = (x << 8) | get8();
x = (x << 8) | get8();
x = (x << 8) | get8();
x = (x << 8) | get8();
x = (x << 8) | get8();
x = (x << 8) | get8();
return (x << 8) | get8();
}
int main(void)
{
s = sparsebit_alloc();
for (;;) {
uint8_t op = get8() & 0xf;
uint64_t first = get64();
uint64_t last = get64();
operate(op, first, last);
}
}
#endif
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