#include <stdio.h>
#include <assert.h>

#include <linux/scatterlist.h>

#define MAX_PAGES (64)

struct test {
        int alloc_ret;
        unsigned num_pages;
        unsigned *pfn;
        unsigned *pfn_app;
        unsigned size;
        unsigned int max_seg;
        unsigned int expected_segments;
};

static void set_pages(struct page **pages, const unsigned *array, unsigned num)
{
        unsigned int i;

        assert(num < MAX_PAGES);
        for (i = 0; i < num; i++)
                pages[i] = (struct page *)(unsigned long)
                           ((1 + array[i]) * PAGE_SIZE);
}

#define pfn(...) (unsigned []){ __VA_ARGS__ }

static void fail(struct test *test, struct sg_table *st, const char *cond)
{
        unsigned int i;

        fprintf(stderr, "Failed on '%s'!\n\n", cond);

        printf("size = %u, max segment = %u, expected nents = %u\nst->nents = %u, st->orig_nents= %u\n",
               test->size, test->max_seg, test->expected_segments, st->nents,
               st->orig_nents);

        printf("%u input PFNs:", test->num_pages);
        for (i = 0; i < test->num_pages; i++)
                printf(" %x", test->pfn[i]);
        printf("\n");

        exit(1);
}

#define VALIDATE(cond, st, test) \
        if (!(cond)) \
                fail((test), (st), #cond);

int main(void)
{
        const unsigned int sgmax = UINT_MAX;
        struct test *test, tests[] = {
                { -EINVAL, 1, pfn(0), NULL, PAGE_SIZE, 0, 1 },
                { 0, 1, pfn(0), NULL, PAGE_SIZE, PAGE_SIZE + 1, 1 },
                { 0, 1, pfn(0), NULL, PAGE_SIZE, sgmax, 1 },
                { 0, 1, pfn(0), NULL, 1, sgmax, 1 },
                { 0, 2, pfn(0, 1), NULL, 2 * PAGE_SIZE, sgmax, 1 },
                { 0, 2, pfn(1, 0), NULL, 2 * PAGE_SIZE, sgmax, 2 },
                { 0, 3, pfn(0, 1, 2), NULL, 3 * PAGE_SIZE, sgmax, 1 },
                { 0, 3, pfn(0, 1, 2), NULL, 3 * PAGE_SIZE, sgmax, 1 },
                { 0, 3, pfn(0, 1, 2), pfn(3, 4, 5), 3 * PAGE_SIZE, sgmax, 1 },
                { 0, 3, pfn(0, 1, 2), pfn(4, 5, 6), 3 * PAGE_SIZE, sgmax, 2 },
                { 0, 3, pfn(0, 2, 1), NULL, 3 * PAGE_SIZE, sgmax, 3 },
                { 0, 3, pfn(0, 1, 3), NULL, 3 * PAGE_SIZE, sgmax, 2 },
                { 0, 3, pfn(1, 2, 4), NULL, 3 * PAGE_SIZE, sgmax, 2 },
                { 0, 3, pfn(1, 3, 4), NULL, 3 * PAGE_SIZE, sgmax, 2 },
                { 0, 4, pfn(0, 1, 3, 4), NULL, 4 * PAGE_SIZE, sgmax, 2 },
                { 0, 5, pfn(0, 1, 3, 4, 5), NULL, 5 * PAGE_SIZE, sgmax, 2 },
                { 0, 5, pfn(0, 1, 3, 4, 6), NULL, 5 * PAGE_SIZE, sgmax, 3 },
                { 0, 5, pfn(0, 1, 2, 3, 4), NULL, 5 * PAGE_SIZE, sgmax, 1 },
                { 0, 5, pfn(0, 1, 2, 3, 4), NULL, 5 * PAGE_SIZE, 2 * PAGE_SIZE,
                  3 },
                { 0, 6, pfn(0, 1, 2, 3, 4, 5), NULL, 6 * PAGE_SIZE,
                  2 * PAGE_SIZE, 3 },
                { 0, 6, pfn(0, 2, 3, 4, 5, 6), NULL, 6 * PAGE_SIZE,
                  2 * PAGE_SIZE, 4 },
                { 0, 6, pfn(0, 1, 3, 4, 5, 6), pfn(7, 8, 9, 10, 11, 12),
                  6 * PAGE_SIZE, 12 * PAGE_SIZE, 2 },
                { 0, 0, NULL, NULL, 0, 0, 0 },
        };
        unsigned int i;

        for (i = 0, test = tests; test->expected_segments; test++, i++) {
                int left_pages = test->pfn_app ? test->num_pages : 0;
                struct sg_append_table append = {};
                struct page *pages[MAX_PAGES];
                int ret;

                set_pages(pages, test->pfn, test->num_pages);

                if (test->pfn_app)
                        ret = sg_alloc_append_table_from_pages(
                                &append, pages, test->num_pages, 0, test->size,
                                test->max_seg, left_pages, GFP_KERNEL);
                else
                        ret = sg_alloc_table_from_pages_segment(
                                &append.sgt, pages, test->num_pages, 0,
                                test->size, test->max_seg, GFP_KERNEL);

                assert(ret == test->alloc_ret);

                if (test->alloc_ret)
                        continue;

                if (test->pfn_app) {
                        set_pages(pages, test->pfn_app, test->num_pages);
                        ret = sg_alloc_append_table_from_pages(
                                &append, pages, test->num_pages, 0, test->size,
                                test->max_seg, 0, GFP_KERNEL);

                        assert(ret == test->alloc_ret);
                }

                VALIDATE(append.sgt.nents == test->expected_segments,
                         &append.sgt, test);
                if (!test->pfn_app)
                        VALIDATE(append.sgt.orig_nents ==
                                         test->expected_segments,
                                 &append.sgt, test);

                if (test->pfn_app)
                        sg_free_append_table(&append);
                else
                        sg_free_table(&append.sgt);
        }

        assert(i == (sizeof(tests) / sizeof(tests[0])) - 1);

        return 0;
}