@@ -1,58 +0,0 @@
-OUTPUT_ARCH(i386)
-OUTPUT_FORMAT(elf32-i386)
-
-PAGE_SIZE = 1 << 12;
-
-MEMORY
-{
-  BOOT_VMA :   ORIGIN = 0x00007C00, LENGTH = 0x00001000
-  KERNEL_VMA :        ORIGIN = 0xC0000000, LENGTH = 0x30000000
-  APPLICATION_VMA :   ORIGIN = 0x10000000, LENGTH = 0xB0000000
-}
-
-SECTIONS
-{
-  BOOT : AT(0x0000)
-  {
-    */boot.o(.*)
-  } >BOOT_VMA
-
-  KERNEL : AT(0x5E00)
-  {
-    */kernel.o(.*)
-    */kernel.o(.bss)
-  } >KERNEL_VMA
-
-  APPLICATION : AT(LOADADDR(KERNEL) + SIZEOF(KERNEL))
-  {
-    */apps.o(.*)
-  } >APPLICATION_VMA
-
-  ELF : AT(0xB600)
-  {
-    */apps_raw.o(.*)
-  } >APPLICATION_VMA
-
-  .bss : AT(LOADADDR(ELF) + SIZEOF(ELF))
-  {
-
-  } >KERNEL_VMA
-}
-
-__BOOT_LMA = LOADADDR(BOOT);
-__BOOT_VMA = ADDR(BOOT);
-__BOOT_SIZE = SIZEOF(BOOT);
-
-__KERNEL_LMA = LOADADDR(KERNEL);
-__KERNEL_VMA = ADDR(KERNEL);
-__KERNEL_SIZE = SIZEOF(KERNEL);
-
-__ELF_LMA = LOADADDR(ELF);
-__ELF_VMA = ADDR(ELF);
-__ELF_SIZE = SIZEOF(ELF);
-
-__KERNEL_STACK_ADDR = 0xC0400000;
-
-ASSERT(__BOOT_SIZE <= 0x1000, "bootloader too big!");
-ASSERT(__KERNEL_SIZE <= 0x5000, "bootloader too big!");
-ASSERT(__ELF_SIZE <= 0x3000, "bootloader too big!");

@@ -146,4 +146,4 @@ .byte 0
 
 a20_enable_fasta20_msg:
   .ascii " fast A20 method: "
-  .byte 0+  .byte 0

@@ -101,6 +101,9 @@ push %cx
   movw $reset_msg, %si
   call print
 
+  lea bootdriv_id, %si
+  movb (%si), %dl
+
   movb $0x00, %ah
   int $0x13
   pop %cx
@@ -142,19 +145,26 @@ # call print_hex_int16
 
   movw %bx, %di
 
+  # divide LBA by number of sectors
   lea num_sectors, %si
+  xor %dx, %dx
   movw (%si), %bx
-  # inc %ax
-  divb %bl
-  movb %ah, %cl
+  divw %bx
+
+  andw $0x003F, %dx
+  movb %dl, %cl
   incb %cl
 
-  xor %ah, %ah
+  xor %dx, %dx
   lea num_heads, %si
   movw (%si), %bx
-  divb %bl
-  movb %ah, %dh
+  divw %bx
   movb %al, %ch
+  movb %ah, %al
+  xorb %ah, %ah
+  shl $6, %al
+  orb %al, %cl
+  movb %dl, %dh
 
   lea bootdriv_id, %si
   movb (%si), %dl
@@ -316,6 +326,7 @@ .byte 13
   .byte 10
   .byte 0
 
+
 .section .bss
 .global bootdriv_id
 bootdriv_id:
@@ -331,4 +342,4 @@ num_cylinders:
   .word 0
 
 num_heads:
-  .word 0+  .word 0

@@ -161,15 +161,29 @@ # perform long jump to set code segment
   ljmp $0x18, $protected
 
 
+myhexdump:
+  movb (%si), %al
+  call print_hex_char
+  inc %si
+  push %si
+  movw $space_msg, %si
+  call print
+  pop %si
+  loop myhexdump
+  movw $newline_msg, %si
+  call print
+  ret
+
+
 .code32
 protected:
   # setup registers with appropriate GDT values
   mov $0x20, %eax
+  mov %eax, %ss
   mov %eax, %ds
   mov %eax, %es
   mov %eax, %fs
   mov %eax, %gs
-  mov %eax, %ss
 
   call load_kernel
   
@@ -194,6 +208,15 @@ jmp loop
  
 
 .section .data 
+space_msg:
+  .ascii " "
+  .byte 0
+
+newline_msg:
+  .byte 13
+  .byte 10
+  .byte 0
+
 gdt_msg:
   .ascii "Setting GDT..."
   .byte 0
@@ -227,9 +250,9 @@ .byte 10
   .byte 0
 
 GDT_DESCRIPTOR:
-  .word 0x39
+  .word 0x37
   .int GDT
 
 IDT_DESCRIPTOR:
   .word 0
-  .int 0+  .int 0

@@ -52,11 +52,7 @@ uint32_t FAT2_lba;
 uint32_t root_lba;
 uint32_t data_lba;
 
-void *FAT_init() {
-    const int sector_size = 512;
-    const int sector_num = 128;
-    const int part_size = sector_size * sector_num;
-
+void FAT_init() {
     // open image file
     FAT_addr = (void*)(0x10000);
 
@@ -109,7 +105,7 @@ return -1;
         }
 
         // deleted file
-        if (dir_entry->name[0] == 0xE5) {
+        if (dir_entry->name[0] == (char)(0xE5)) {
             index++;
             continue;
         }
@@ -169,7 +165,7 @@ }
 
 uint16_t FAT_next_cluster(uint16_t cluster) {
     // assuming FAT12
-    int offset = (cluster >> 1) * 3;
+    uint32_t offset = (cluster >> 1) * 3;
     uint8_t *sect = FAT_read_sector_offset(FAT1_lba, &offset);
     sect += offset;
 

@@ -3,7 +3,7 @@ #define FAT_H
 
 #include <stdint.h>
 
-void *FAT_init();
+void FAT_init();
 void *FAT_read_sector_offset(uint32_t lba, uint32_t *offset);
 void *FAT_read_cluster(uint16_t cluster, void *buffer);
 uint16_t FAT_next_cluster(uint16_t cluster);

@@ -8,6 +8,7 @@
 MEMORY
 {
   BOOT_VMA    :   ORIGIN = 0x00007C00, LENGTH = 0x00001000
+  BOOT_DATA   :   ORIGIN = 0x00009000, LENGTH = 0x00001000
   KERNEL_VMA  :   ORIGIN = 0xC0000000, LENGTH = 0x30000000
 }
 
@@ -20,7 +21,16 @@ . = 510;
     BYTE(0x55)
     BYTE(0xAA)
     */*.o(.text)
-    */*.o(.data)
+  } >BOOT_VMA
+
+  .data : 
+  {
     */*.o(.rodata*)
+    */*.o(.data)
   } >BOOT_VMA
+
+  .bss : 
+  {
+    */*.o(.bss)
+  } >BOOT_DATA
 }

@@ -16,6 +16,22 @@ }
 }
 
 int load_kernel() {
+    // debug output
+    uint8_t *dbuf = (uint8_t *)(0x10000);
+    for (int i = 0; i < 16; i++) {
+        uint8_t value = dbuf[i];
+        char lut[] = "0123456789ABCDEF";
+
+        uint8_t low = value & 0x0F;
+        uint8_t high = value >> 4;
+
+        printc(lut[high]);
+        printc(lut[low]);
+        printc(' ');
+    }
+
+    //while (1);
+
     FAT_init();
 
     int i = 0;
@@ -38,10 +54,8 @@ }
 
     // copy all clusters
     uint16_t cluster = first_cluster;
-    void *buffer = (void *)(0x100000);
+    uint8_t *buffer = (uint8_t *)(0x100000);
     while (1) {
-        uint8_t *str = (uint8_t*)(0xB8000);
-
         buffer = FAT_read_cluster(cluster, buffer);
         cluster = FAT_next_cluster(cluster);
         

@@ -86,4 +86,4 @@
 newline:
   .byte 13
   .byte 10
-  .byte 0+  .byte 0

@@ -29,7 +29,9 @@ void *memcpy(void *_dest, const void *_src, uint32_t n) {
     uint8_t *src = (uint8_t*)(_src);
     uint8_t *dest = (uint8_t*)(_dest);
 
-    for (int i = 0; i < n; i++) {
+    for (uint32_t i = 0; i < n; i++) {
         dest[i] = src[i];
     }
+
+    return _dest;
 }