partial fat12 structs recovered from forum

diff --git a/kernel/fat12/fat12.asm b/kernel/fat12/fat12.asm
index d079a13babcfcb78391913886c69e869271e336e..0b87c662ac429bc8c56b9596fef857f546482251 100644 (file)
--- a/kernel/fat12/fat12.asm
+++ b/kernel/fat12/fat12.asm
@@ -5,6 +5,55 @@
 ;    FAT12 driver.                                         ;
 ;                                                          ;
 ;----------------------------------------------------------;
+      struc disk
+      {
+          .disk_number         db  0                  ; which disk?
+          .root_dir            dw  0                  ; position of rootdir
+          .fat_1               dd  0                  ; position of fat1
+          .fat_2               dd  0                  ; position of fat2
+          .data_area           dw  0                  ; position of dataarea
+          .disk_size           dd  0
+          .free_space          dd  0
+          .boot                bootsector  
+          ; ..... some other values
+      }
+      struc bootsector                                ; 512 bytes
+      {
+          .jumper              db  0,0,0
+          .oem                 db  0,0,0,0,0,0,0,0
+          .sectorsize          dw  0
+          .sect_per_clust      db  0  
+          ;.... more values here
+      }
+
+      virtual at 0
+          bootsector bootsector
+          sizeof.bootsector = $
+      end virtual
+
+      virtual at 0
+          disk disk 
+          sizeof.disk = $     
+      end virtual
+
+
+fd0 disk            ; define fd0 data..  
+
+;drv dd 0
+;mov edi, drv+disk.boot
+
+     ;-----------------------------; 
+     ;   calculate root location   ; 
+     ;-----------------------------; 
+          xor     eax, eax 
+          mov     al, byte [fd0.boot.fats_per_drive] 
+          mul     word [fd0.boot.sectors_per_fat] 
+          add     ax, word [fd0.boot.reserved_sect] 
+          mov     [fd0.root_dir], ax  
+
+;mov  si, [dsk] 
+;mov  ax, [si+disk.boot.sectorssize] 
+
 
 init_fat12:
         push   eax