/*
 * This program demonstrates MIPS cache virtual aliasing problem,
 * apply to cpus that use virtually indexed cache and each set of
 * cache has a size greater than PAGE_SIZE.
 *
 * If the machines failes the test, you will see a bunch of error emssage:
 *  int at 568 is not 5
 *  ....
 */

#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <assert.h>
#include <signal.h>

int fid[2][2];
int fid_read, fid_write;

#define PAGE_SIZE	4096

#define SUSPEND_CONTROL { int x; read(fid_read, &x, sizeof(x)); }
#define RESUME_CONTROL  { int x; write(fid_write, &x, sizeof(x)); }
#define TRANSFER_CONTROL {int x; write(fid_write, &x, sizeof(x)); read(fid_read, &x, sizeof(x)); }

static void my_sig_handler(int signum)
{

}

void do_process_A()
{
	int fd;
	int * base;
	int i;

        fid_write = fid[0][1];
        fid_read = fid[1][0];

        printf("A : open file");
	fd=open("mmap-test", O_RDWR);
	assert(fd > 0);

	base=mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	printf("  map base is %p (@=%d)\n", base, *base);

        TRANSFER_CONTROL;

        printf("A: flash base page with 5\n");
	for (i=0; i<1024; i++)
		base[i] = 5;

        TRANSFER_CONTROL;

	munmap(base, PAGE_SIZE);
	close(fd);

        exit(0);
}

void do_process_B()
{
	int fd;
	int * base;
	int * base1;
	int i;

        fid_read = fid[0][0];
        fid_write = fid[1][1];

        SUSPEND_CONTROL;
        printf("B : open file");
	fd=open("mmap-test", O_RDWR);
	assert(fd > 0);

	base1=mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, PAGE_SIZE);
	base=mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	printf("  map base is %p(@=%d)\n", base, *base);

        TRANSFER_CONTROL;
        printf("B : check page at base \n", *base);
	for (i=0; i<1024; i++)
		if (base[i] != 5) printf("int at %d is not 5\n", i);

        RESUME_CONTROL;
	munmap(base, PAGE_SIZE);
	munmap(base1, PAGE_SIZE);
	close(fd);

        exit(0);
}

main()
{
        pipe(fid[0]);
        pipe(fid[1]);

	{ 
		/* create two page file with 0s */
		int i;
		int zero=0;
		int fd;

		fd=open("mmap-test", O_CREAT | O_RDWR );
		assert(fd > 0);
		for (i=0; i< 2*PAGE_SIZE; i++) 
			assert(write(fd, &zero, 1)==1);
		assert(close(fd) == 0);
	}

        if (fork()) {
                do_process_B();
                do_process_A();
                assert(1 ==0);
        }

        if (fork()) {
                do_process_A();
                assert(1 ==0);
        }

        wait(NULL);
        wait(NULL);
}