/*
 * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de.
 * Distributed under the terms of the MIT License.
 */

#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>


#ifndef PAGE_SIZE
#       define PAGE_SIZE 4096
#endif

#define PAGE_ELEMENT_COUNT      (PAGE_SIZE / 4)


int
main(int argc, const char* const* argv)
{
        size_t allocationSize = 256;

        if (argc > 1) {
                allocationSize = atoi(argv[1]);
                if (allocationSize == 0) {
                        fprintf(stderr, "Usage: %s [ <size in MB> ]\n", argv[0]);
                        return 1;
                }
        }

        allocationSize *= 1024 * 1024;
        size_t elementCount = allocationSize / 4;
        size_t pageCount = elementCount / PAGE_ELEMENT_COUNT;

        // allocate memory
        uint32_t* allocation = (uint32_t*)malloc(allocationSize);
        if (allocation == NULL) {
                fprintf(stderr, "Allocation failed!\n");
                return 1;
        }

        printf("Allocated %lu MB at %p. Filling the allocation...\n",
                (unsigned long)allocationSize / 1024 / 1024, allocation);

        // fill the pages
        for (size_t i = 0; i < elementCount; i++) {
                allocation[i] = i;
                if ((i + 1) % (PAGE_ELEMENT_COUNT * 32) == 0) {
                        printf("\rfilled %9lu/%9lu pages",
                                (unsigned long)(i + 1) / PAGE_ELEMENT_COUNT,
                                (unsigned long)pageCount);
                        fflush(stdout);
                }
        }

        printf("\rDone filling the allocation. Starting test iterations...\n");

        for (int testIteration = 0; testIteration < 5; testIteration++) {
                sleep(1);

                printf("Test iteration %d...\n", testIteration);

                // test the pages
                for (size_t i = 0; i < elementCount; i++) {
                        if (allocation[i] != i) {
                                printf("  incorrect value in page %lu\n",
                                        (unsigned long)i / PAGE_ELEMENT_COUNT);

                                // skip the rest of the page
                                i = i / PAGE_ELEMENT_COUNT * PAGE_ELEMENT_COUNT
                                        + PAGE_ELEMENT_COUNT - 1;
                        } else if ((i + 1) % PAGE_ELEMENT_COUNT == 0) {
//                              printf("  page %lu ok\n",
//                                      (unsigned long)i / PAGE_ELEMENT_COUNT);
                        }
                }
        }

        return 0;
}