We can now read from the disk in protected mode

Makefile

@@ -2,7 +2,7 @@ CFLAGS = -m32 -mgeneral-regs-only -nostdlib -fno-builtin -fno-exceptions -fno-le
 LDFLAGS = 
 
 DISK_IMG_FILES = kernel.bin hello.bin print.bin boot32.bin kernel32.bin
-KERNEL32_OBJS = screenstuff.o io.o idt.o keyboard.o strings.o kernel32_strap.o kernel32.o
+KERNEL32_OBJS = screenstuff.o io.o idt.o keyboard.o strings.o atapio.o kernel32_strap.o kernel32.o
 
 run: disk.img
 	qemu-system-x86_64 disk.img

atapio.c

@@ -0,0 +1,122 @@
+#include "atapio.h"
+
+// Disk code
+
+// Primary ATA Bus: 0x1f0 to 0x1f7
+// Device Control Register: 0x3f6
+// Secondary ATA Bus: 0x170 to 0x177
+// Device Control Register: 0x376
+
+
+uint16_t identify_result[256];
+uint32_t total_28_lbas = 0;
+
+uint8_t* rootDirEntries = 0x1000000;
+uint16_t* FAT1 = 0x1002000;
+
+uint16_t countReserved;
+uint8_t countFATs;
+uint16_t countRDEs;
+uint16_t sectorsPerFAT;
+
+
+void init_atapio() {
+  countReserved = *(uint16_t*)0x7c0e;
+  countFATs = *(uint8_t*)0x7c10;
+  countRDEs = *(uint16_t*)0x7c11;
+  sectorsPerFAT = *(uint16_t*)0x7c16;
+
+  // Select Drive 0 on the Primary Bus
+  outb(0x1f6, 0xa0);
+
+  // Set sector count to 0 for IDENTIFY
+  outb(0x1f2, 0);
+  // Set LBAlo to 0
+  outb(0x1f3, 0);
+  // Set LBAmid to 0
+  outb(0x1f4, 0);
+  // Set LBAhi to 0
+  outb(0x1f5, 0);
+
+  // Send IDENTIFY command
+  outb(0x1f7, 0xec);
+
+  uint8_t status = inb(0x1f7);
+  if (status) {
+    while ((status = inb(0x1f7)) & 0x80);
+
+    if ( !(inb(0x1f4) || inb(0x1f5)) ) {
+      while ( !(status & 8 || status & 1) )
+        status = inb(0x1f7);
+      
+      if (!(status & 1)) {
+        for (int index=0; index<256; index++)
+          identify_result[index] = inw(0x1f0);
+      }
+    }
+  }
+
+  total_28_lbas = *(uint32_t*)(identify_result+60);
+
+  // We've initialised now, let's load the FAT and RootDirEntries.
+  read_sectors(sectorsPerFAT * countFATs + 1, countRDEs / 16, rootDirEntries);
+  read_sectors(1, sectorsPerFAT, FAT1);
+}
+
+void read_sector(uint32_t address, uint8_t* buffer) {
+  outb(0x1f6, 0xe0 | ((address>>24)&0x0f));
+  // Read a single sector
+  outb(0x1f2, 1);
+  // Set LBAlo, LBAmid and LBAhi
+  outb(0x1f3, address);
+  outb(0x1f4, address>>8);
+  outb(0x1f5, address>>16);
+
+  // Send read command 
+  outb(0x1f7, 0x20);
+  // Poll
+  uint8_t status = inb(0x1f7);
+  while ( (status & 0x80) && !(status & 8) )
+    status = inb(0x1f7);
+
+  for (int index=0; index<256; index++)
+    ((uint16_t*)buffer)[index] = inw(0x1f0);
+}
+
+void read_sectors(uint32_t address, int count, uint8_t* buffer) {
+  for (int i=0; i<count; i++) {
+    read_sector(address+i, buffer+512*i);
+    for (int i=0; i<15; i++)
+      inb(0x1f7);
+  } 
+}
+
+uint16_t file_exists(char* filename) {
+  for (int i=0; i<countRDEs; i++) {
+    bool found = strcmp(rootDirEntries+(i*32), filename, 11);
+    if (found) {
+      uint16_t* correctEntry = (rootDirEntries+(i*32));
+      return correctEntry[13];
+    }
+  }
+  return 0;
+}
+
+void load_file(char* filename, uint8_t* destination) {
+  uint16_t location = file_exists(filename);
+  if (!location)
+    return;
+
+  int offset = 0;
+
+  bool loaded = false;
+  while (!loaded) {
+    uint16_t fromSector = location + (sectorsPerFAT * countFATs) + (countRDEs / 16) - 1;
+    read_sector(fromSector, destination+offset);
+    offset += 512;
+
+    location = FAT1[location++];
+    if (location == 0xffff)
+      loaded = true;
+  }
+}

atapio.h

@@ -0,0 +1,17 @@
+#ifndef ATA_PIO
+#define ATA_PIO
+
+#include <stdbool.h>
+
+#include "io.h"
+#include "types.h"
+#include "strings.h"
+#include "screenstuff.h"
+
+void init_atapio();
+void read_sector(uint32_t address, uint8_t* buffer);
+void read_sectors(uint32_t address, int count, uint8_t* buffer);
+uint16_t file_exists(char* filename);
+void load_file(char* filename, uint8_t* location);
+
+#endif

kernel32.c

@@ -3,8 +3,8 @@
 #include "io.h"
 #include "idt.h"
 #include "keyboard.h"
-
 #include "strings.h"
+#include "atapio.h"
 
 int main() {
   init_idt();
@@ -16,6 +16,18 @@ int main() {
 
   init_keyboard();
   enable_idt();
+  init_atapio();
+
+  uint8_t sector[512];
+
+  read_sector(0, sector);
+
+  printf("OEM ID: %s\n", (char*)(sector+0x3));
+
+  char hellotxt[1024];
+
+  load_file("HELLO   TXT", hellotxt);
+  printf("%s", hellotxt);
 
 
   while (1) {
@@ -32,12 +44,12 @@ int main() {
       printf(
         "XnoeOS 32 Bit Mode Help.\n"
         "------------------------\n"
-        "- help\n"
+        " - help\n"
-        ": Shows this message\n"
+        " : Shows this message\n"
-        "- clear\n"
+        " - clear\n"
-        ": Clears the screen\n"
+        " : Clears the screen\n"
         " - echo\n"
-        ": Repeats the text written afterwards\n"
+        " : Repeats the text written afterwards\n"
       );
     } else if (strcmp(buffer, "clear", 5)) {
       clear_screen();