range.c

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/*
 * Range add and subtract
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sort.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;

    /* Try to merge it with old one: */
    for (i = 0; i < nr_range; i++) {
        u64 final_start, final_end;
        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;

        final_start = min(range[i].start, start);
        final_end = max(range[i].end, end);

        range[i].start = final_start;
        range[i].end =  final_end;
        return nr_range;
    }

    /* 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 {
                printk(KERN_ERR "run of slot in ranges\n");
            }
            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;
    s64 start1, start2;

    start1 = r1->start;
    start2 = r2->start;

    return start1 - start2;
}

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);
}