Changeset 553 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Handlers

Timestamp:

Jun 8, 2013, 10:32:10 AM (12 years ago)

Author:

aitotat@…

google:author:

aitotat@gmail.com

Message:

Changes to XTIDE Universal BIOS:

• Standard boot procedure (INT 19h) works again.

Location:

trunk/XTIDE_Universal_BIOS/Src/Handlers

Files:

• Int13hBiosInit.asm (modified) (2 diffs)
• Int19h.asm (modified) (1 diff)

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13hBiosInit.asm

@@ -28 +28 @@
     LOAD_BDA_SEGMENT_TO ds, ax
 
-    ; Restore system INT 13h handler that we backuped
-    les     ax, [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4]
-    mov     [BIOS_DISK_INTERRUPT_13h*4], ax
-    mov     [BIOS_DISK_INTERRUPT_13h*4+2], es
-
     ; Now install our handler and call 19h since non-standard motherboard BIOS did not
     ; do that or our INT 19h hander was replaced by other BIOS.
@@ -38 +33 @@
     mov     [BIOS_BOOT_LOADER_INTERRUPT_19h*4+2], cs
     int     BIOS_BOOT_LOADER_INTERRUPT_19h  ; Does not return
+
+
+;--------------------------------------------------------------------
+; Int13hBiosInit_RestoreSystemHandler
+;   Parameters:
+;       Nothing
+;   Returns:
+;       Nothing
+;   Corrupts registers:
+;       AX, DS, ES
+;--------------------------------------------------------------------
+Int13hBiosInit_RestoreSystemHandler:
+    LOAD_BDA_SEGMENT_TO ds, ax
+
+    ; Is our very late init handler in place
+    cmp     WORD [BIOS_DISK_INTERRUPT_13h*4], Int13hBiosInit_Handler
+    jne     SHORT .SystemHandlerAlreadyInPlace
+
+    les     ax, [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4]
+    mov     [BIOS_DISK_INTERRUPT_13h*4], ax
+    mov     [BIOS_DISK_INTERRUPT_13h*4+2], es
+.SystemHandlerAlreadyInPlace:
+    ret

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm

@@ -29 +29 @@
 ;--------------------------------------------------------------------
 Int19h_BootLoaderHandler:
-    sti                                 ; Enable interrupts
-    cld                                 ; String instructions to increment pointers
-    LOAD_BDA_SEGMENT_TO es, ax          ; Load BDA segment (zero) to ES
+    sti                                         ; Enable interrupts
+    cld                                         ; String instructions to increment pointers
+    call    Int13hBiosInit_RestoreSystemHandler ; Needed if initialization was started on INT 13h instead on 19h
+    LOAD_BDA_SEGMENT_TO es, ax                  ; Load BDA segment (zero) to ES
     ; Fall to .PrepareBootLoaderStack