Changeset 275 in xtideuniversalbios

Timestamp:

Feb 28, 2012, 1:25:33 PM (12 years ago)

Author:

gregli@…

google:author:

gregli@hotmail.com

Message:

Made some tweaks to ah0h, saving some space by taking advantage of DPT=null indicating foreign drive.

File:

• trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH0h_HReset.asm (modified) (3 diffs)

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH0h_HReset.asm

@@ -15 +15 @@
 ;       DL:     Translated Drive number (ignored so all drives are reset)
 ;               If bit 7 is set all hard disks and floppy disks reset.
-;       DS:DI:  Ptr to DPT (only if DL is our drive)
+;       DS:DI:  Ptr to DPT (or Null if foreign drive)
 ;       SS:BP:  Ptr to IDEPACK
 ;   Returns with INTPACK:
@@ -51 +51 @@
     call    ResetForeignHardDisks
 
-    ; Resetting our hard disks will modify dl and bl such that this call must be the last in the list
-    call    GetDriveNumberForForeignHardDiskHandlerToDL ; Load DPT for our drive
-    jc      SHORT .SkipHardDiskReset                    ; Our drive not requested so let's not reset them
+    test    di, di
+    jz      SHORT .SkipHardDiskReset
+
+    ; Resetting our hard disks will modify dl and bl to be idevars offset based instead of drive number based, 
+    ; such that this call must be the last in the list of reset routines called.
+    ;
     call    ResetHardDisksHandledByOurBIOS          
 
@@ -118 +121 @@
 ;       DS:     RAMVARS segment
 ;   Returns:
-;       DS:DI:  Ptr to DPT if our drive
+;       DS:DI:  Ptr to DPT if our drive (or Null if foreign drive)
 ;       DL:     BL if foreign drive
 ;               80h if our drive
-;       CF:     Set if foreign drive
-;               Cleared if our drive
-;   Corrupts registers:
-;       (DI)
 ;--------------------------------------------------------------------
 GetDriveNumberForForeignHardDiskHandlerToDL:
     mov     dl, bl
-    call    FindDPT_ForDriveNumberInDL
-    jc      SHORT .ReturnWithForeignDriveInDL
+    test    di, di
+    jz      SHORT .Return
     mov     dl, 80h             ; First possible Hard Disk should be safe value
-.ReturnWithForeignDriveInDL:
+.Return:
     ret
 
-
-;--------------------------------------------------------------------
-; AH0h_ResetAllOurHardDisksAtTheEndOfDriveInitialization
-;   Parameters:
-;       DS:     RAMVARS segment
-;       SS:BP:  Ptr to IDEPACK
-;   Returns:
-;       Nothing
-;   Corrupts registers:
-;       AX, BX, CX, DX, SI, DI
-;--------------------------------------------------------------------
-AH0h_ResetAllOurHardDisksAtTheEndOfDriveInitialization:
-    mov     bl, [RAMVARS.bFirstDrv]
-    call    GetDriveNumberForForeignHardDiskHandlerToDL
-    ; Fall to ResetHardDisksHandledByOurBIOS
+AH0h_ResetAllOurHardDisksAtTheEndOfDriveInitialization equ ResetHardDisksHandledByOurBIOS.ErrorCodeNotUsed
 
 ;--------------------------------------------------------------------
 ; ResetHardDisksHandledByOurBIOS
 ;   Parameters:
-;       BL:     Requested drive (DL when entering AH=00h)
 ;       DS:DI:  Ptr to DPT for requested drive
+;               If DI is Null (foreign drive), or if error result in BH won't be used,
+;               enter through .ErrorCodeNotUsed, to avoid di=Null dereference
 ;       SS:BP:  Ptr to IDEPACK
 ;   Returns:
 ;       BH:     Error code from requested drive (if available)
 ;   Corrupts registers:
-;       AX, CX, DX, SI, DI
+;       AX, BX, CX, DX, SI, DI
 ;--------------------------------------------------------------------
 ResetHardDisksHandledByOurBIOS:
     mov     bl, [di+DPT.bIdevarsOffset]                 ; replace drive number with Idevars pointer for cmp with dl
+
+.ErrorCodeNotUsed:                                      ; BH will be garbage if thie entry point is used, 
+                                                        ; but reset of all drives will still happen
+
     mov     dl, ROMVARS.ideVars0                        ; starting Idevars offset