#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>

#include "util.h"

/* Measure the time it takes to access a block with virtual address addr. */
CYCLES measure_one_block_access_time(ADDR_PTR addr)
{
	CYCLES cycles;

	asm volatile("mov %1, %%r8\n\t"
	"lfence\n\t"
	"rdtsc\n\t"
	"mov %%eax, %%edi\n\t"
	"mov (%%r8), %%r8\n\t"
	"lfence\n\t"
	"rdtsc\n\t"
	"sub %%edi, %%eax\n\t"
	: "=a"(cycles) /*output*/
	: "r"(addr)
	: "r8", "edi");	

	return cycles;
}

/*
 * CLFlushes the given address.
 * 
 * Note: clflush is provided to help you debug and should not be used in your
 * final submission
 */
void clflush(ADDR_PTR addr)
{
    asm volatile ("clflush (%0)"::"r"(addr));
}

int fd;
size_t file_size;

char *allocate_shared_buffer() {
    const char *filepath = "shared_file";

    int fd = open(filepath, O_RDONLY, (mode_t)0600);

    if (fd == -1)
    {
        perror("Error opening file for writing, please run `python3 gen_file.py` to get the file for shared buf");
        exit(EXIT_FAILURE);
    }

    struct stat fileInfo = {0};

    if (fstat(fd, &fileInfo) == -1)
    {
        perror("Error getting the file size");
        exit(EXIT_FAILURE);
    }

    if (fileInfo.st_size == 0)
    {
        fprintf(stderr, "Error: File is empty, nothing to do\n");
        exit(EXIT_FAILURE);
    }

    if (fileInfo.st_size < SEC_RANGE * ALIGN) {
        close(fd);
        perror("File is too small\n");
        exit(EXIT_FAILURE);
    }

    char *buf = mmap(0, fileInfo.st_size, PROT_READ, MAP_SHARED, fd, 0);
    if (buf == MAP_FAILED)
    {
        close(fd);
        perror("Error mmapping the file");
        exit(EXIT_FAILURE);
    }
    file_size = fileInfo.st_size;
    return buf;
}

void deallocate_shared_buffer(char *buf) {
    // Don't forget to free the mmapped memory
    if (munmap(buf, file_size) == -1)
    {
        close(fd);
        perror("Error un-mmapping the file");
        exit(EXIT_FAILURE);
    }

    // Un-mmaping doesn't close the file, so we still need to do that.
    close(fd);
}