// SPDX-License-Identifier: GPL-2.0
/*
 * Range add and subtract
 */
#include <linux/init.h>
#include <linux/minmax.h>
#include <linux/printk.h>
#include <linux/sort.h>
#include <linux/string.h>
#include <linux/range.h>

int add_range(struct range *range, int az, int nr_range, u64 start, u64 end)
{
        if (start >= end)
                return nr_range;

        /* Out of slots: */
        if (nr_range >= az)
                return nr_range;

        range[nr_range].start = start;
        range[nr_range].end = end;

        nr_range++;

        return nr_range;
}

int add_range_with_merge(struct range *range, int az, int nr_range,
                     u64 start, u64 end)
{
        int i;

        if (start >= end)
                return nr_range;

        /* get new start/end: */
        for (i = 0; i < nr_range; i++) {
                u64 common_start, common_end;

                if (!range[i].end)
                        continue;

                common_start = max(range[i].start, start);
                common_end = min(range[i].end, end);
                if (common_start > common_end)
                        continue;

                /* new start/end, will add it back at last */
                start = min(range[i].start, start);
                end = max(range[i].end, end);

                memmove(&range[i], &range[i + 1],
                        (nr_range - (i + 1)) * sizeof(range[i]));
                range[nr_range - 1].start = 0;
                range[nr_range - 1].end   = 0;
                nr_range--;
                i--;
        }

        /* Need to add it: */
        return add_range(range, az, nr_range, start, end);
}

void subtract_range(struct range *range, int az, u64 start, u64 end)
{
        int i, j;

        if (start >= end)
                return;

        for (j = 0; j < az; j++) {
                if (!range[j].end)
                        continue;

                if (start <= range[j].start && end >= range[j].end) {
                        range[j].start = 0;
                        range[j].end = 0;
                        continue;
                }

                if (start <= range[j].start && end < range[j].end &&
                    range[j].start < end) {
                        range[j].start = end;
                        continue;
                }


                if (start > range[j].start && end >= range[j].end &&
                    range[j].end > start) {
                        range[j].end = start;
                        continue;
                }

                if (start > range[j].start && end < range[j].end) {
                        /* Find the new spare: */
                        for (i = 0; i < az; i++) {
                                if (range[i].end == 0)
                                        break;
                        }
                        if (i < az) {
                                range[i].end = range[j].end;
                                range[i].start = end;
                        } else {
                                pr_err("%s: run out of slot in ranges\n",
                                        __func__);
                        }
                        range[j].end = start;
                        continue;
                }
        }
}

static int cmp_range(const void *x1, const void *x2)
{
        const struct range *r1 = x1;
        const struct range *r2 = x2;

        if (r1->start < r2->start)
                return -1;
        if (r1->start > r2->start)
                return 1;
        return 0;
}

int clean_sort_range(struct range *range, int az)
{
        int i, j, k = az - 1, nr_range = az;

        for (i = 0; i < k; i++) {
                if (range[i].end)
                        continue;
                for (j = k; j > i; j--) {
                        if (range[j].end) {
                                k = j;
                                break;
                        }
                }
                if (j == i)
                        break;
                range[i].start = range[k].start;
                range[i].end   = range[k].end;
                range[k].start = 0;
                range[k].end   = 0;
                k--;
        }
        /* count it */
        for (i = 0; i < az; i++) {
                if (!range[i].end) {
                        nr_range = i;
                        break;
                }
        }

        /* sort them */
        sort(range, nr_range, sizeof(struct range), cmp_range, NULL);

        return nr_range;
}

void sort_range(struct range *range, int nr_range)
{
        /* sort them */
        sort(range, nr_range, sizeof(struct range), cmp_range, NULL);
}