commit f92798f4aedcc4a06901a491e30daf3bfec9e04c
Author: Mysaa <mysaa@bernard.com.de>
Date:   Mon May 24 12:48:25 2021 +0200

    Premier commit - Inclusion dans le système git

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e108870
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.classpath
+.project
+.settings
+bin/
diff --git a/src/com/bernard/exfatdemerde/ExfatChecksumCalculator.java b/src/com/bernard/exfatdemerde/ExfatChecksumCalculator.java
new file mode 100644
index 0000000..b70a8cb
--- /dev/null
+++ b/src/com/bernard/exfatdemerde/ExfatChecksumCalculator.java
@@ -0,0 +1,47 @@
+package com.bernard.exfatdemerde;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Scanner;
+
+public class ExfatChecksumCalculator {
+	
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		System.out.println("Chemin du fichier ?");
+		File f = new File(sc.nextLine());
+		if(!f.exists()) {
+			System.err.println("ERREUR: le fichier spécifié est introuvable");sc.close();return;
+		}
+		System.out.println("Nombre de bytes par secteur ?");
+		int byteCount = 11*sc.nextInt();
+		System.out.println("Lecture de "+byteCount+" octets");
+		
+		try (FileInputStream fis = new FileInputStream(f)){
+			byte[] data = new byte[byteCount];
+			fis.read(data);
+			int checksum = exfatBootChecksum(data, byteCount);
+			System.out.println("Voila la checksum que j'ai calculée :");
+			System.out.println(Integer.toString(checksum));
+			System.out.println("0x"+Integer.toHexString(checksum));
+		}catch(IOException e) {
+			e.printStackTrace();
+		}
+		
+		System.out.println("\n\nTadaaaaaaaaaa");
+		sc.close();
+	}
+	
+	public static final int exfatBootChecksum(byte[] data, long bytes){
+	    int checksum = 0; 
+	    for (int i = 0 ; i < bytes ; i++){
+	        if (i == 106 || i == 107 || i == 112)
+	            continue;
+	        checksum = ((byte)((checksum&0xFF) << 31)) | (((byte)((checksum&0xFF) >> 1)) + ((byte)(data[i]&0xFF)));
+	        //System.out.println("Checksum :"+Integer.toHexString(checksum));
+	    }
+	    return checksum;
+	}
+	
+}