Changeset 39 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Initialization

Timestamp:

Sep 13, 2010, 11:16:42 AM (14 years ago)

Author:

Tomi Tilli

google:author:

aitotat

Message:

• Better INT 40h handler detection to fix floppy drive detection with AMI 286 BIOS.

File:

• trunk/XTIDE_Universal_BIOS/Src/Initialization/FloppyDrive.asm (modified) (2 diffs)

trunk/XTIDE_Universal_BIOS/Src/Initialization/FloppyDrive.asm

@@ -2 +2 @@
 ; Project name  :   IDE BIOS
 ; Created date  :   25.3.2010
-; Last update   :   28.7.2010
+; Last update   :   13.9.2010
 ; Author        :   Tomi Tilli
 ; Description   :   Various floppy drive related functions that
@@ -22 +22 @@
 ;       BX, CX, DI
 ;--------------------------------------------------------------------   
-ALIGN JUMP_ALIGN
+;ALIGN JUMP_ALIGN
 FloppyDrive_IsInt40hInstalled:
     cmp     WORD [es:INTV_FLOPPY_FUNC*4+2], 0C000h  ; Any ROM segment?
+    jb      SHORT .Int40hHandlerIsNotInstalled
+    call    .VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h
+.Int40hHandlerIsNotInstalled:
     cmc
+    ret
+
+;--------------------------------------------------------------------
+; .VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h
+;   Parameters:
+;       Nothing
+;   Returns:
+;       CF:     Cleared if INT 40h is installed
+;               Set if INT 40h is not installed
+;   Corrupts registers:
+;       BX, CX, DI
+;--------------------------------------------------------------------   
+;ALIGN JUMP_ALIGN
+.VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h:
+    push    es
+    push    dx
+    push    ax
+
+    call    .LoadInt40hVerifyParameters
+    int     INTV_DISK_FUNC
+    jc      SHORT .AH08hNotSupported    ; AH=08h not supported on XTs but that doesn't
+    push    es                          ; matter since INT 40h does not need to be verified
+    push    di                          ; on XTs
+
+    call    .LoadInt40hVerifyParameters
+    int     INTV_FLOPPY_FUNC
+
+    pop     dx
+    pop     cx
+    cmp     dx, di                      ; Difference in offsets?
+    jne     SHORT .Int40hNotInstalled
+    mov     dx, es
+    cmp     cx, dx                      ; Difference in segments?
+    jne     SHORT .Int40hNotInstalled
+.AH08hNotSupported:
+    clc
+    jmp     SHORT .Int40hIsInstalled
+.Int40hNotInstalled:
+    stc
+.Int40hIsInstalled:
+    pop     ax
+    pop     dx
+    pop     es
+    ret
+
+;--------------------------------------------------------------------
+; .LoadInt40hVerifyParameters
+;   Parameters:
+;       Nothing
+;   Returns:
+;       AH:     08h (Get Drive Parameters)
+;       DL:     00h (floppy drive)
+;       ES:DI:  0:0h (to guard against BIOS bugs)
+;   Corrupts registers:
+;       DH
+;--------------------------------------------------------------------   
+;ALIGN JUMP_ALIGN
+.LoadInt40hVerifyParameters:
+    xor     dx, dx              ; Floppy drive 0
+    mov     di, dx
+    mov     es, dx              ; ES:DI = 0000:0000h to guard against BIOS bugs
+    mov     ah, 08h             ; Get Drive Parameters
     ret