Added filesys.h header for better file r/w api

include/disk/filesys.h

@@ -0,0 +1,114 @@
+#ifndef FILESYS_H
+#define FILESYS_H
+
+#include <disk/disk.h>
+#include <memory/addresses.h>
+#include <screen/text.h>
+#include <string.h>
+
+typedef struct {
+    char filename[10];
+    char filetype[3];
+    uint8_t reserved;
+    uint8_t startAddress;
+    uint8_t length;
+} __attribute__ ((packed)) fileEntry_t;
+
+char* filetable = (char*)FILETABLE_LOC; // Pretty sure we don't have to care about the bootloader at 0x7c00
+
+fileEntry_t* findFile(char* filename) { // TODO: Don't modify the filename string. (maybe make a copy??)
+    char* filetype = strchr(filename, '.');
+    *filetype++ = '\0'; // Split filename and filetype by a NULL
+
+    char* ft = filetable;
+    while (*ft != '\0') {
+        if (strcmp(filename, ft) != 0) { // Filename doesn't match
+            ft += 16; // Goto next entry
+            continue;
+        }
+        ft += 10; // Goto filetype
+        
+        if (strcmp(filetype, ft) != 0) {
+            ft += 6; // Goto next entry
+            continue;
+        }
+        ft -= 10; // Go back to start of entry
+        
+        return (fileEntry_t*)ft;
+    }
+
+    return NULL; // No such file
+}
+
+void updateFiletable() {
+    // TODO: Update the filetable by writing data from memory to disk!
+}
+
+void readFile(char* filename, void* buffer) { // Hopefully the buffer is large enought :/
+    fileEntry_t* file = findFile(filename);
+    if (file == NULL) { return; } // File doesn't exist!
+
+    diskRead(file->startAddress, file->length, buffer);
+}
+
+void writeFile(char* filename, void* buffer) { // TODO: Add length so we don't write too much/too little
+    fileEntry_t* file = findFile(filetable);
+    if (file == NULL) { // File exists -> override
+        // File doesn't exist -> create new file
+        file = (fileEntry_t*)filetable;
+        while (*(char*)file != '\0') { file++; } // Find end of the filetable
+         
+        // strchr(filename, '.'); TODO: We don't have to do this, because findFile() modifies the string like this
+        char* filetype = filename + strlen(filename); // + 1?
+        fileEntry_t* previous = file - 1;
+
+        strcpy(file->filename, filename);
+        strcpy(file->filetype, filetype);
+        file->startAddress = previous->startAddress + previous->length;
+        file->length = 1; // TODO: Add lenght! Currently will just assume 1 sector :/
+    }
+
+    diskWrite(file->startAddress, file->length, buffer); // Write the file
+}
+
+void printFiletable(char* ft) {
+    while (*ft != '\0') {
+        char filename[15] = { 0 };
+        uint8_t offset = 0;
+        for (uint8_t i = 0; i < 14; i++) {
+            if (i == 9) {
+                filename[offset++] = '.';
+                continue;
+            }
+            if (*ft != '\0') { filename[offset++] = *ft; }
+            ft++;
+        }
+        ft++; // RESERVED
+
+        uint8_t sector = *ft++;
+        uint8_t size = *ft++;
+
+        if (sector < 10) putc('0');
+        if (sector == 0) putc('0');
+        else print(itoa(sector, 10));
+        print(": ");
+        print(filename);
+
+        for (uint8_t i = 14 - strlen(filename); i > 0; i--) {
+            putc(' ');
+        }
+
+        print(" | ");
+        if (size >> 1) {
+            print(itoa(size >> 1, 10));
+            if (size & 0x01) { print(".5"); }
+            print("kB\n");
+        } else {
+            print(itoa(size*512, 10));
+            print("B\n");
+        }
+    }
+}
+
+
+#endif