Memroy mapping Hutter Prize Enwik9

OpenEnwik.c

//Full guide : https://leetarxiv.substack.com/p/hutter-prize-beginners-guide-to-writing
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <math.h>
#include <sys/mman.h>
#include <stdbool.h>
#define INDEX(x, y, cols) ((x) * (cols) + (y))

//clear && gcc main.c -lm -o m.o && ./m.o
size_t GetFileSize(char *fileName)
{
	FILE *fp = fopen(fileName, "rb");
	assert(fp != NULL);
	fseek(fp, 0L, SEEK_END);
	size_t currentFileSize = ftell(fp);rewind(fp);
	fclose(fp);
	return currentFileSize;
}


unsigned char *LoadData(char *fileName, size_t *fileSizeHolder)
{
	size_t fileSize = GetFileSize(fileName);
	FILE *fp = fopen(fileName, "rb");assert(fp != NULL);
	int fileNumber = fileno(fp);
	unsigned char *fileData = mmap(NULL,fileSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileNumber, 0);
	assert(fileData != MAP_FAILED);
	fclose(fp);
	*fileSizeHolder = fileSize;
	return fileData;
}



int main()
{
	char *fileName = "enwik9";
	size_t fileSize = 0;
	unsigned char *data = LoadData(fileName, &fileSize); 
	
	
	assert(munmap(data, fileSize) != -1);
	return 0;
}