#include <stdio.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

void hex_dump (char *desc, void *addr, int len) {
    int i;
    unsigned char buff[17];
    unsigned char *pc = (unsigned char*)addr;

    // Output description if given.
    if (desc != NULL)
        printf ("%s:\n", desc);

    if (len == 0) {
        printf("  ZERO LENGTH\n");
        return;
    }
    if (len < 0) {
        printf("  NEGATIVE LENGTH: %i\n",len);
        return;
    }

    // Process every byte in the data.
    for (i = 0; i < len; i++) {
        // Multiple of 16 means new line (with line offset).

        if ((i % 16) == 0) {
            // Just don't print ASCII for the zeroth line.
            if (i != 0)
                printf ("  %s\n", buff);

            // Output the offset.
            printf ("  %04x ", i);
        }

        // Now the hex code for the specific character.
        printf (" %02x", pc[i]);

        // And store a printable ASCII character for later.
        if ((pc[i] < 0x20) || (pc[i] > 0x7e))
            buff[i % 16] = '.';
        else
            buff[i % 16] = pc[i];
        buff[(i % 16) + 1] = '\0';
    }

    // Pad out last line if not exactly 16 characters.
    while ((i % 16) != 0) {
        printf ("   ");
        i++;
    }

    // And print the final ASCII bit.
    printf ("  %s\n", buff);
}

int main(int argc, char *argv[])
{
        char hostname[9] = "test";
	char *mem;
	int pages = 1024;
	int size = sysconf(_SC_PAGESIZE) * pages;
	int count;
	int step = 0;
	int ret;
	char *org;
	int dump = 0;

	mem = (char *)malloc(size);
	org = (char *)malloc(sysconf(_SC_PAGESIZE));
	printf("Setting memory to 0x42\n");
	memset(mem, 0x42, size);
	memset(org, 0x42, sysconf(_SC_PAGESIZE));
	printf("mem %p\n", mem);
	printf("org %p\n", org);

	while (1) {
		for (count = 0; count < pages; count+=2) {
			(mem+(count*sysconf(_SC_PAGESIZE)))[128] = count;
		}
		hostname[8] = 0;
		printf("Checking if org page is still 0x42\n");
		for (count = 1; count < sysconf(_SC_PAGESIZE); count++) {
			if (org[count] != 0x42) {
				printf("org differs at %d\n", count);
			}
		}

		printf("Checking if all of mem is the same as org\n");
		for (count = 0; count < pages; count++) {
			if (count%2 == 0)
				org[128] = count;
			else
				org[128] = 0x42;
			ret = memcmp(org, mem+(count*sysconf(_SC_PAGESIZE)), sysconf(_SC_PAGESIZE));
			if (ret) {
				printf("memcmp found difference at %d(%p)\n", count, mem+(count*sysconf(_SC_PAGESIZE)));
				if (dump < 4) {
					hex_dump ("page", mem+(count*sysconf(_SC_PAGESIZE)), sysconf(_SC_PAGESIZE));
					hex_dump ("org", org, sysconf(_SC_PAGESIZE));
				}
				dump++;
			}
		}

		printf("Step %d on %s\n", step++, hostname);
		gethostname(hostname, 8);
		printf("Sleeping 1\n");
		sleep(1);
		dump = 0;
	}
	return 0;
}