Changeset 597 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm

Timestamp:

Jul 11, 2018, 9:44:43 AM (6 years ago)

Author:

aitotat

Message:

Windows 95 CMOS hack now works with Award BIOSes.
Some small optimizations to INT 19h and INT 19h reset handlers.
Added menuitem to configurator for clearing BDA drive count.

File:

• trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm (modified) (3 diffs)

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm

@@ -199 +199 @@
     call    DriveXlate_Reset                    ; Clean up any drive mappings before Rom Boot
 %endif
-    clc
-    ;; fall through to Int19h_JumpToBootSectorOrRomBoot
-
-;--------------------------------------------------------------------
-; Int19h_JumpToBootSectorOrRomBoot
+    stc
+    ;; fall through to Int19h_JumpToBootSectorInESBXOrRomBoot
+
+;--------------------------------------------------------------------
+; Int19h_JumpToBootSectorInESBXOrRomBoot
 ;
 ; Switches back to the POST stack, clears the DS and ES registers,
@@ -211 +211 @@
 ;   Parameters:
 ;       DL:     Drive to boot from (translated, 00h or 80h)
-;       CF:     Set for Boot Sector Boot
-;               Clear for ROM Boot
-;       ES:BX:  (if CF set) Ptr to boot sector (ES = zero)
+;       CF:     Clear for Boot Sector Boot
+;               Set for ROM Boot
+;       ES:BX:  (if CF clear) Ptr to boot sector (ES = zero)
 ;
 ;   Returns:
 ;       Never returns
 ;--------------------------------------------------------------------
-Int19h_JumpToBootSectorOrRomBoot:
-    mov     ax, es      ; Preserve MBR segment (can't push because of stack change)
-                        ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF
+Int19h_JumpToBootSectorInESBXOrRomBoot:
+    mov     ax, es      ; Clear AX. NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF
     SWITCH_BACK_TO_POST_STACK
 
 ; clear segment registers before boot sector or rom call
+Int19h_JumpToBootSectorInESBXOrRomBootWithoutStackChange:
+    mov     ax, es      ; Clear AX and preserve CF
     mov     ds, ax
 %ifdef USE_386
@@ -229 +230 @@
     mov     gs, ax
 %endif
-    jnc     SHORT .RomBoot
+    jc      SHORT .RomBoot
 
 ; jump to boot sector
-    push    ax          ; sgment address for MBR
+    push    es          ; sgment address for MBR
     push    bx          ; offset address for MBR
     retf                ; NOTE: DL is set to the drive number