/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  (C) 2012  Michel Lespinasse <walken@google.com>


  tools/linux/include/linux/rbtree_augmented.h

  Copied from:
  linux/include/linux/rbtree_augmented.h
*/

#ifndef _TOOLS_LINUX_RBTREE_AUGMENTED_H
#define _TOOLS_LINUX_RBTREE_AUGMENTED_H

#include <linux/compiler.h>
#include <linux/rbtree.h>

/*
 * Please note - only struct rb_augment_callbacks and the prototypes for
 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
 * The rest are implementation details you are not expected to depend on.
 *
 * See Documentation/core-api/rbtree.rst for documentation and samples.
 */

struct rb_augment_callbacks {
        void (*propagate)(struct rb_node *node, struct rb_node *stop);
        void (*copy)(struct rb_node *old, struct rb_node *new);
        void (*rotate)(struct rb_node *old, struct rb_node *new);
};

extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
        void (*augment_rotate)(struct rb_node *old, struct rb_node *new));

/*
 * Fixup the rbtree and update the augmented information when rebalancing.
 *
 * On insertion, the user must update the augmented information on the path
 * leading to the inserted node, then call rb_link_node() as usual and
 * rb_insert_augmented() instead of the usual rb_insert_color() call.
 * If rb_insert_augmented() rebalances the rbtree, it will callback into
 * a user provided function to update the augmented information on the
 * affected subtrees.
 */
static inline void
rb_insert_augmented(struct rb_node *node, struct rb_root *root,
                    const struct rb_augment_callbacks *augment)
{
        __rb_insert_augmented(node, root, augment->rotate);
}

static inline void
rb_insert_augmented_cached(struct rb_node *node,
                           struct rb_root_cached *root, bool newleft,
                           const struct rb_augment_callbacks *augment)
{
        if (newleft)
                root->rb_leftmost = node;
        rb_insert_augmented(node, &root->rb_root, augment);
}

/*
 * Template for declaring augmented rbtree callbacks (generic case)
 *
 * RBSTATIC:    'static' or empty
 * RBNAME:      name of the rb_augment_callbacks structure
 * RBSTRUCT:    struct type of the tree nodes
 * RBFIELD:     name of struct rb_node field within RBSTRUCT
 * RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
 * RBCOMPUTE:   name of function that recomputes the RBAUGMENTED data
 */

#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,                          \
                             RBSTRUCT, RBFIELD, RBAUGMENTED, RBCOMPUTE) \
static inline void                                                      \
RBNAME ## _propagate(struct rb_node *rb, struct rb_node *stop)          \
{                                                                       \
        while (rb != stop) {                                            \
                RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD);       \
                if (RBCOMPUTE(node, true))                              \
                        break;                                          \
                rb = rb_parent(&node->RBFIELD);                         \
        }                                                               \
}                                                                       \
static inline void                                                      \
RBNAME ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)         \
{                                                                       \
        RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD);            \
        RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD);            \
        new->RBAUGMENTED = old->RBAUGMENTED;                            \
}                                                                       \
static void                                                             \
RBNAME ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)       \
{                                                                       \
        RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD);            \
        RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD);            \
        new->RBAUGMENTED = old->RBAUGMENTED;                            \
        RBCOMPUTE(old, false);                                          \
}                                                                       \
RBSTATIC const struct rb_augment_callbacks RBNAME = {                   \
        .propagate = RBNAME ## _propagate,                              \
        .copy = RBNAME ## _copy,                                        \
        .rotate = RBNAME ## _rotate                                     \
};

/*
 * Template for declaring augmented rbtree callbacks,
 * computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
 *
 * RBSTATIC:    'static' or empty
 * RBNAME:      name of the rb_augment_callbacks structure
 * RBSTRUCT:    struct type of the tree nodes
 * RBFIELD:     name of struct rb_node field within RBSTRUCT
 * RBTYPE:      type of the RBAUGMENTED field
 * RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
 * RBCOMPUTE:   name of function that returns the per-node RBTYPE scalar
 */

#define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD,         \
                                 RBTYPE, RBAUGMENTED, RBCOMPUTE)              \
static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit)          \
{                                                                             \
        RBSTRUCT *child;                                                      \
        RBTYPE max = RBCOMPUTE(node);                                         \
        if (node->RBFIELD.rb_left) {                                          \
                child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD);   \
                if (child->RBAUGMENTED > max)                                 \
                        max = child->RBAUGMENTED;                             \
        }                                                                     \
        if (node->RBFIELD.rb_right) {                                         \
                child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD);  \
                if (child->RBAUGMENTED > max)                                 \
                        max = child->RBAUGMENTED;                             \
        }                                                                     \
        if (exit && node->RBAUGMENTED == max)                                 \
                return true;                                                  \
        node->RBAUGMENTED = max;                                              \
        return false;                                                         \
}                                                                             \
RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,                                        \
                     RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max)


#define RB_RED          0
#define RB_BLACK        1

#define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))

#define __rb_color(pc)     ((pc) & 1)
#define __rb_is_black(pc)  __rb_color(pc)
#define __rb_is_red(pc)    (!__rb_color(pc))
#define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
#define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
#define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
{
        rb->__rb_parent_color = rb_color(rb) + (unsigned long)p;
}

static inline void rb_set_parent_color(struct rb_node *rb,
                                       struct rb_node *p, int color)
{
        rb->__rb_parent_color = (unsigned long)p + color;
}

static inline void
__rb_change_child(struct rb_node *old, struct rb_node *new,
                  struct rb_node *parent, struct rb_root *root)
{
        if (parent) {
                if (parent->rb_left == old)
                        WRITE_ONCE(parent->rb_left, new);
                else
                        WRITE_ONCE(parent->rb_right, new);
        } else
                WRITE_ONCE(root->rb_node, new);
}

extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
        void (*augment_rotate)(struct rb_node *old, struct rb_node *new));

static __always_inline struct rb_node *
__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
                     const struct rb_augment_callbacks *augment)
{
        struct rb_node *child = node->rb_right;
        struct rb_node *tmp = node->rb_left;
        struct rb_node *parent, *rebalance;
        unsigned long pc;

        if (!tmp) {
                /*
                 * Case 1: node to erase has no more than 1 child (easy!)
                 *
                 * Note that if there is one child it must be red due to 5)
                 * and node must be black due to 4). We adjust colors locally
                 * so as to bypass __rb_erase_color() later on.
                 */
                pc = node->__rb_parent_color;
                parent = __rb_parent(pc);
                __rb_change_child(node, child, parent, root);
                if (child) {
                        child->__rb_parent_color = pc;
                        rebalance = NULL;
                } else
                        rebalance = __rb_is_black(pc) ? parent : NULL;
                tmp = parent;
        } else if (!child) {
                /* Still case 1, but this time the child is node->rb_left */
                tmp->__rb_parent_color = pc = node->__rb_parent_color;
                parent = __rb_parent(pc);
                __rb_change_child(node, tmp, parent, root);
                rebalance = NULL;
                tmp = parent;
        } else {
                struct rb_node *successor = child, *child2;

                tmp = child->rb_left;
                if (!tmp) {
                        /*
                         * Case 2: node's successor is its right child
                         *
                         *    (n)          (s)
                         *    / \          / \
                         *  (x) (s)  ->  (x) (c)
                         *        \
                         *        (c)
                         */
                        parent = successor;
                        child2 = successor->rb_right;

                        augment->copy(node, successor);
                } else {
                        /*
                         * Case 3: node's successor is leftmost under
                         * node's right child subtree
                         *
                         *    (n)          (s)
                         *    / \          / \
                         *  (x) (y)  ->  (x) (y)
                         *      /            /
                         *    (p)          (p)
                         *    /            /
                         *  (s)          (c)
                         *    \
                         *    (c)
                         */
                        do {
                                parent = successor;
                                successor = tmp;
                                tmp = tmp->rb_left;
                        } while (tmp);
                        child2 = successor->rb_right;
                        WRITE_ONCE(parent->rb_left, child2);
                        WRITE_ONCE(successor->rb_right, child);
                        rb_set_parent(child, successor);

                        augment->copy(node, successor);
                        augment->propagate(parent, successor);
                }

                tmp = node->rb_left;
                WRITE_ONCE(successor->rb_left, tmp);
                rb_set_parent(tmp, successor);

                pc = node->__rb_parent_color;
                tmp = __rb_parent(pc);
                __rb_change_child(node, successor, tmp, root);

                if (child2) {
                        successor->__rb_parent_color = pc;
                        rb_set_parent_color(child2, parent, RB_BLACK);
                        rebalance = NULL;
                } else {
                        unsigned long pc2 = successor->__rb_parent_color;
                        successor->__rb_parent_color = pc;
                        rebalance = __rb_is_black(pc2) ? parent : NULL;
                }
                tmp = successor;
        }

        augment->propagate(tmp, NULL);
        return rebalance;
}

static __always_inline void
rb_erase_augmented(struct rb_node *node, struct rb_root *root,
                   const struct rb_augment_callbacks *augment)
{
        struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
        if (rebalance)
                __rb_erase_color(rebalance, root, augment->rotate);
}

static __always_inline void
rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
                          const struct rb_augment_callbacks *augment)
{
        if (root->rb_leftmost == node)
                root->rb_leftmost = rb_next(node);
        rb_erase_augmented(node, &root->rb_root, augment);
}

#endif /* _TOOLS_LINUX_RBTREE_AUGMENTED_H */