From 487ecc1615ccc0368f1520c1146b2b43cdab6577 Mon Sep 17 00:00:00 2001
From: Michal Idziorek <m.i@gmx.at>
Date: Thu, 4 Sep 2014 20:17:49 +0200
Subject: working on bootloader. we will need stage 2...

---
 boot/disk_load_16.asm | 131 ++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 106 insertions(+), 25 deletions(-)

(limited to 'boot/disk_load_16.asm')

diff --git a/boot/disk_load_16.asm b/boot/disk_load_16.asm
index 2fa88ee..eae15a0 100644
--- a/boot/disk_load_16.asm
+++ b/boot/disk_load_16.asm
@@ -9,6 +9,21 @@
 
 DISK_LOAD:
     db "D",0
+DISK_LOAD_ERROR
+    db "E",0
+Head:
+    db 0
+Track:
+    db 0
+Sector:
+    db 1
+LBA:
+    dw 0 ;; starts at zero!
+Sectors:
+    dw 80
+Heads:
+    dw 2
+
 
 ;disk_load routune (load dh sectors from drive dl to es:bx)
 ;lba mode has 52 sectors hardcoded!
@@ -16,47 +31,113 @@ disk_load_16:
 
     pusha
     
+;;;    ; check if LBA is supported
+;;;    pusha
+;;;    mov    ah,0x41
+;;;    mov    bx,0x55aa
+;;;    int    0x13                                                    
+;;;    jnc disk_load_lba
+;;;    popa
 
-    ; check if LBA is supported
-    pusha
-    mov    ah,0x41
-    mov    bx,0x55aa
-    int    0x13                                                    
-    jnc disk_load_lba
-    popa
+    disk_load_next:
+
+    call ESBX
 
     ; load using CHS 
+;;    mov al,80		;read dh sectors (amount)
+;;    mov cx,[LBA]
+;;    cmp cx,0
+;;    jne disk_read_normal
+;;    mov al,79		;read dh sectors (amount)
+;;    disk_read_normal
+
+    mov al,1
+
+    mov cl,[Sector]	;sector
+    mov ch,[Track]	;cyl
+
+    mov dl,[BOOT_DRIVE]
+    mov dh,[Head]	;head
+
     mov ah,0x02		;BIOS read sector func
-    mov al,dh		;read dh sectors (amount)
-    mov ch,0x00		;cyl 0
-    mov dh,0x00		;head 0
-    mov cl,0x02		;start at sector 2
-;
     int 0x13		;bios interrupt
 
-    mov bx, DISK_LOAD
+    jnc disk_read_ok  ;ready becaue of error :(
+
+    mov bx, DISK_LOAD_ERROR
     call print_string
 
-    popa
-    ret
-    
-    ; load using LBA
+    jmp $
 
-disk_load_lba:
+    disk_read_ok:
 
-    popa
+    mov ax,[LBA]
+
+    cmp ax,880
+    je disk_load_ready
 
-    xor ah,ah
-    mov ah,0x42
-    lea si,[lba_adr]        
-    int 0x13  
-    jc skip_print
     mov bx, DISK_LOAD
     call print_string
-    skip_print:
+
+    add ax,1	;conver LBA to CHS
+    mov [LBA],ax
+
+    call LBACHS
+
+    jmp disk_load_next
+
+    disk_load_ready:
+
+    jmp $
 
     popa
     ret
+   
+ESBX:
+
+    xor dx,dx
+    xor dx,dx
+    mov ax,[LBA]
+    mov bx,0x200
+    mul bx
+    mov bx,ax
+    add dx,1
+    shl dx,12
+    mov es,dx
+
+ret
+
+
+    ; load using LBA
+
+;;;disk_load_lba:
+;;;
+;;;    popa
+;;;
+;;;    xor ah,ah
+;;;    mov ah,0x42
+;;;    lea si,[lba_adr]        
+;;;    int 0x13  
+;;;    jc skip_print
+;;;    mov bx, DISK_LOAD
+;;;    call print_string
+;;;    skip_print:
+;;;
+;;;    popa
+;;;    ret
+;;;
+LBACHS:
+          xor     dx, dx                              ; prepare dx:ax for operation
+          div     WORD [Sectors]           ; divide by sectors per track
+          inc     dl                                  ; add 1 (obsolute sector formula)
+          mov     BYTE [Sector], dl
+ 
+          xor     dx, dx                              ; prepare dx:ax for operation
+          div     WORD [Heads]          ; mod by number of heads (Absolue head formula)
+          mov     BYTE [Head], dl             ; everything else was already done from the first formula
+ 
+          mov     BYTE [Track], al            ; not much else to do :)
+          ret
 
 lba_adr:
 
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