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Diffstat (limited to 'tools/testing/selftests/kvm/lib/sparsebit.c')
| -rw-r--r-- | tools/testing/selftests/kvm/lib/sparsebit.c | 2087 |
1 files changed, 2087 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/sparsebit.c b/tools/testing/selftests/kvm/lib/sparsebit.c new file mode 100644 index 000000000000..0c5cf3e0cb6f --- /dev/null +++ b/tools/testing/selftests/kvm/lib/sparsebit.c @@ -0,0 +1,2087 @@ +/* + * Sparse bit array + * + * Copyright (C) 2018, Google LLC. + * Copyright (C) 2018, Red Hat, Inc. (code style cleanup and fuzzing driver) + * + * This work is licensed under the terms of the GNU GPL, version 2. + * + * 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 divisable 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(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(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(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(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(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(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 = NULL; + + 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(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, 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, 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(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(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(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(struct sparsebit *s) +{ + return s->num_set; +} + +/* Returns whether any bit is set in the sparsebit array. */ +bool sparsebit_any_set(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(struct sparsebit *s) +{ + return !sparsebit_any_set(s); +} + +/* Returns whether all the bits in the sparsebit array are set. */ +bool sparsebit_any_clear(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(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(struct sparsebit *s) +{ + struct node *nodep1, *nodep2; + + /* Validate |