Changeset 533 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm

Timestamp:

Apr 3, 2013, 4:12:34 PM (11 years ago)

Author:

aitotat@…

google:author:

aitotat@gmail.com

Message:

Changes to XTIDE Universal BIOS:

• P-Cylinders returned by AH=48h are now calculated from L-CHS capacity when RESERVE_DIAGNOSTIC_CYLINDER is defined.
• Total sector count returned by AH=48h is now always P-Cylinders * P-Heads * P-Sectors per track for drives with less than or equal 15,482,880 LBA sectors.

File:

• trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm (modified) (2 diffs)

trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm

@@ -118 +118 @@
     mov     [di+DPT.bPchsHeads], bl
 %ifdef MODULE_EBIOS
+    mov     [di+DPT.bPchsSectorsPerTrack], bh
+
+%ifdef RESERVE_DIAGNOSTIC_CYLINDER
+    ; Do not store P-Cylinders, instead calculate it from L-CHS total sector count.
+    ; Read AH=48h_GetExtendedDriveParameters.asm for more info.
+    xchg    ax, bx
+    mul     ah
+    push    ax                          ; P-Heads * P-Sectors per track
+    call    AH15h_GetSectorCountToBXDXAX
+    pop     bx
+    div     bx                          ; AX = Calculated cylinders
+%endif ; RESERVE_DIAGNOSTIC_CYLINDER
+
     mov     [di+DPT.wPchsCylinders], ax
-    mov     [di+DPT.bPchsSectorsPerTrack], bh
     ; Fall to .StoreNumberOfLbaSectors
 
@@ -141 +153 @@
     call    StoreLba48AddressingFromCLandTotalSectorCountFromBXDXAX
 
+    ; If we have 15,482,880 or less sectors, we multiply P-CHS values
+    ; and use that as total sector count.
+    ; Read AH=48h_GetExtendedDriveParameters.asm for more info.
+    sub     ax, 4001h
+    sbb     dx, 0ECh
+    sbb     bx, BYTE 0
+    jnc     SHORT .NoNeedToUseCHSsectorCount    ; More than EC4000h
+
+    mov     al, [di+DPT.bPchsHeads]
+    mul     BYTE [di+DPT.bPchsSectorsPerTrack]
+    mul     WORD [di+DPT.wPchsCylinders]
+    xor     bx, bx
+    call    StoreLba48AddressingFromCLandTotalSectorCountFromBXDXAX
+
     ; Load user defined LBA
+.NoNeedToUseCHSsectorCount:
     call    GetUserDefinedCapacityToBXAXandFlagsToCXandModeToDXfromROMVARS
     test    cl, FLG_DRVPARAMS_USERLBA