Changeset 227 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/AccessDPT.asm

Timestamp:

Jan 29, 2012, 1:33:44 PM (12 years ago)

Author:

aitotat@…

google:author:

aitotat@gmail.com

Message:

Changes to XTIDE Universal BIOS:

• EBIOS functions now work in lite mode.

File:

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

trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/AccessDPT.asm

@@ -40 +40 @@
     ret
 
-        
+
 ;--------------------------------------------------------------------
-; AccessDPT_GetLCHS
+; AccessDPT_GetLCHStoAXBLBH
 ;   Parameters:
 ;       DS:DI:  Ptr to Disk Parameter Table
 ;   Returns:
-;       AX:     Number of L-CHS sectors per track
-;       BX:     Number of L-CHS cylinders
-;       DX:     Number of L-CHS heads
+;       AX:     Number of L-CHS cylinders
+;       BL:     Number of L-CHS heads
+;       BH:     Number of L-CHS sectors per track
 ;   Corrupts registers:
-;       CX
+;       CX, DX
 ;--------------------------------------------------------------------
-AccessDPT_GetLCHS:
-    ; Load CHS from DPT
-    eMOVZX  ax, BYTE [di+DPT.bSectors]
-    mov     bx, [di+DPT.dwCylinders]
-    cwd
-    mov     dl, [di+DPT.bHeads]
+AccessDPT_GetLCHStoAXBLBH:
+    ; Return LBA-assisted CHS if LBA addressing used
+    test    BYTE [di+DPT.bFlagsLow], FLG_DRVNHEAD_LBA
+    jz      SHORT .ConvertPchsToLchs
 
-    ; Only need to limit sectors for LBA assist
-    test    BYTE [di+DPT.bFlagsLow], FLG_DRVNHEAD_LBA
-    jz      SHORT AccessDPT_ShiftPCHinBXDXtoLCH
+    call    AccessDPT_GetLbaSectorCountToBXDXAX
+    call    AtaID_GetLbaAssistedCHStoDXAXBLBH
+    test    dx, dx
+    jnz     SHORT .LimitAXtoMaxLCHScylinders
+    cmp     ax, MAX_LCHS_CYLINDERS
+    jbe     SHORT .returnLCHS
+.LimitAXtoMaxLCHScylinders:
+    mov     ax, MAX_LCHS_CYLINDERS
+.returnLCHS:
+    ret
 
-    cmp     WORD [di+DPT.dwCylinders+2], BYTE 0
-    jnz     SHORT .Return_MAX_LCHS_CYLINDERS
+.ConvertPchsToLchs:
+    mov     ax, [di+DPT.wPchsCylinders]
+    mov     bx, [di+DPT.wPchsHeadsAndSectors]
+    jmp     SHORT AccessDPT_ShiftPCHinAXBLtoLCH
 
-    ; Limit cylinders to 1024
-    cmp     bx, MAX_LCHS_CYLINDERS
-    jb      SHORT .Return
-ALIGN JUMP_ALIGN
-.Return_MAX_LCHS_CYLINDERS:
-    mov     bx, MAX_LCHS_CYLINDERS
-ALIGN JUMP_ALIGN, ret
-.Return:
+
+;--------------------------------------------------------------------
+; AccessDPT_GetLbaSectorCountToBXDXAX
+;   Parameters:
+;       DS:DI:  Ptr to Disk Parameter Table
+;   Returns:
+;       BX:DX:AX:   48-bit sector count
+;   Corrupts registers:
+;       Nothing
+;--------------------------------------------------------------------
+AccessDPT_GetLbaSectorCountToBXDXAX:
+    mov     ax, [di+DPT.twLbaSectors]
+    mov     dx, [di+DPT.twLbaSectors+2]
+    mov     bx, [di+DPT.twLbaSectors+4]
     ret
 
 
 ;--------------------------------------------------------------------
-; AccessDPT_ShiftPCHinBXDXtoLCH
+; AccessDPT_ShiftPCHinAXBLtoLCH
 ;   Parameters:
-;       BX:     P-CHS cylinders (1...16383)
-;       DX:     P-CHS heads (1...16)
+;       AX:     P-CHS cylinders (1...16383)
+;       BL:     P-CHS heads (1...16)
 ;   Returns:
-;       BX:     Number of L-CHS cylinders (1...1024)
-;       DX:     Number of L-CHS heads (1...255)
+;       AX:     Number of L-CHS cylinders (1...1024)
+;       BL:     Number of L-CHS heads (1...255)
 ;       CX:     Number of bits shifted
 ;   Corrupts registers:
 ;       Nothing
 ;--------------------------------------------------------------------
-AccessDPT_ShiftPCHinBXDXtoLCH:
+AccessDPT_ShiftPCHinAXBLtoLCH:
     xor     cx, cx
 .ShiftLoop:
-    cmp     bx, MAX_LCHS_CYLINDERS      ; Need to shift?
+    cmp     ax, MAX_LCHS_CYLINDERS      ; Need to shift?
     jbe     SHORT .LimitHeadsTo255      ;  If not, return
     inc     cx                          ; Increment shift count
-    shr     bx, 1                       ; Halve cylinders
-    shl     dx, 1                       ; Double heads
+    shr     ax, 1                       ; Halve cylinders
+    shl     bl, 1                       ; Double heads
     jmp     SHORT .ShiftLoop
 .LimitHeadsTo255:                       ; DOS does not support drives with 256 heads
-    sub     dl, dh                      ; DH set only when 256 logical heads
-    xor     dh, dh
+    cmp     bl, cl                      ; Set CF if BL is zero
+    sbb     bl, ch                      ; If BL=0 then BL=255
     ret
 
-        
+
 ;--------------------------------------------------------------------
 ; Returns pointer to DRVPARAMS for master or slave drive.
@@ -144 +157 @@
     and     al, MASKL_DPT_ADDRESSING_MODE
 %endmacro
-
-