Lab9: hexdump names

lab9/bitwise.c

@@ -28,7 +28,7 @@ void printd_inodes(uint8_t* inodes) {
     printf("Debug: ");
 
     for (int i = 0; i < NB_NODES; i++) {
-        printf("%x", inodes[i]);
+        printf("%02x", inodes[i]);
 
         if (i == NB_NODES - 1) {
             printf("\n");
@@ -56,10 +56,6 @@ int main(void) {
     printd_inodes(inodes);
 
     FILE* f = fopen("bits.out", "wb");
-
-    char debug_msg[] = "Debug: ";
-    fwrite(debug_msg, sizeof(char), sizeof(debug_msg), f);
-
     fwrite(inodes, sizeof(uint8_t), NB_NODES, f);
     fclose(f);
 

lab9/bitwise_with_names.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>  // This gives us sized types
+#include <stdbool.h>
+#include <assert.h>
+
+#define NB_NODES 4
+
+bool add_file(uint64_t* inodes, int file_size, char name[7]) {
+    // We only have 7 bits for the file size, so it can't be bigger
+    if (file_size > 0x7f || file_size < 0) {
+        return false;
+    }
+
+    for (int i = 0; i < NB_NODES; i++) {
+        bool is_taken = ((inodes[i] >> (7*8)) & 0x8) > 0;
+
+        if (!is_taken) {
+            // Set highest bit
+            inodes[i] = ((uint64_t) file_size | 0x80) << (7*8);
+
+            // Set name byte by byte
+            for (int ii = 0; ii < 7; ii++) {
+                inodes[i] |= (((uint64_t) name[ii]) & 0xff) << (ii*8);
+            }
+            return true;
+        }
+    }
+
+    return false;
+}
+
+void printd_inodes(uint64_t* inodes) {
+    printf("Debug with name: ");
+
+    for (int i = 0; i < NB_NODES; i++) {
+        for (int ii = 0; ii < 7; ii++) {
+            // Get character out
+            printf("%c", (uint8_t) ((inodes[i] >> (ii*8)) & 0xff));
+        }
+
+        printf(" %02x", (uint8_t) (inodes[i] >> (7*8)));
+
+        if (i == NB_NODES - 1) {
+            printf("\n");
+        } else {
+            printf(" ");
+        }
+    }
+}
+
+int main(void) {
+    // Use bottom 8 bits for file size (7 bits) and occupied indicator (1 bit)
+    // Use top 56 bits for 7 character name
+    uint64_t* inodes = calloc(NB_NODES, sizeof(uint64_t));
+
+    printd_inodes(inodes);
+
+    add_file(inodes, 8, "one\0\0\0");
+    printd_inodes(inodes);
+
+    add_file(inodes, 12, "two\0\0\0");
+    printd_inodes(inodes);
+
+    assert(add_file(inodes, 121, "another"));
+    printd_inodes(inodes);
+
+    add_file(inodes, 127, "four\0\0");
+    printd_inodes(inodes);
+
+    FILE* f = fopen("bits.out", "wb");
+    fwrite(inodes, sizeof(uint64_t), NB_NODES, f);
+    fclose(f);
+
+    free(inodes);
+}