Changeset 230 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h

Timestamp:

Jan 29, 2012, 11:22:19 PM (13 years ago)

Author:

krille_n_@…

google:author:

krille_n_@hotmail.com

Message:

Changes to XTIDE Universal BIOS:

• Some small optimizations

Location:

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h

Files:

• EBIOS/AH48h_GetExtendedDriveParameters.asm (modified) (1 diff)
• Tools/Address.asm (modified) (2 diffs)

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/EBIOS/AH48h_GetExtendedDriveParameters.asm

@@ -45 +45 @@
     mov     WORD [si+EDRIVE_INFO.wFlags], FLG_DMA_BOUNDARY_ERRORS_HANDLED_BY_BIOS
 
+    push    ds  ; Move CS to DS to avoid segment overrides
+    push    cs
+    pop     ds
+
     ; Limit LBA if necessary
-    test    BYTE [cs:di+DRVPARAMS.wFlags], FLG_DRVPARAMS_USERLBA
+    test    BYTE [di+DRVPARAMS.wFlags], FLG_DRVPARAMS_USERLBA
     jz      SHORT .StoreTotalSectorsFromBXDXAX
     test    bx, bx
     jnz     SHORT .LimitTotalSectors
-    cmp     dx, [cs:di+DRVPARAMS.dwMaximumLBA+2]
+    cmp     dx, [di+DRVPARAMS.dwMaximumLBA+2]
     jb      SHORT .StoreTotalSectorsFromBXDXAX      ; Real size less than max
     ja      SHORT .LimitTotalSectors
-    cmp     ax, [cs:di+DRVPARAMS.dwMaximumLBA]
+    cmp     ax, [di+DRVPARAMS.dwMaximumLBA]
     jbe     SHORT .StoreTotalSectorsFromBXDXAX      ; Real size less than max
 
 .LimitTotalSectors:
     xor     bx, bx
-    mov     ax, [cs:di+DRVPARAMS.dwMaximumLBA]
-    mov     dx, [cs:di+DRVPARAMS.dwMaximumLBA+2]
+    mov     ax, [di+DRVPARAMS.dwMaximumLBA]
+    mov     dx, [di+DRVPARAMS.dwMaximumLBA+2]
 
 .StoreTotalSectorsFromBXDXAX:
+    pop     ds  ; Restore DS from the change above
     mov     [si+EDRIVE_INFO.qwTotalSectors], ax
     xor     ax, ax                                  ; Return with success

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/Tools/Address.asm

@@ -86 +86 @@
 Address_OldInt13hAddressToIdeAddress:
         call    Address_ExtractLCHSparametersFromOldInt13hAddress
-            
+
         AccessDPT_GetUnshiftedAddressModeToALZF
-        
-;;; 0: ADDR_DPT_LCHS        
-        jz      DoNotConvertLCHS    
-        
+
+;;; 0: ADDR_DPT_LCHS
+        jz      DoNotConvertLCHS
+
 ;;; 1: ADDR_DPT_PCHS
-        ; 
+        ;
         ; Since we are only checking for zero, we can do our math in the high order bits,
         ; in this case effectively subtracting 1 from the address mode.
         ;
         sub     al,(1<<ADDRESSING_MODE_FIELD_POSITION)
-        jz      ConvertLCHStoPCHS   
+        jz      ConvertLCHStoPCHS
 
-;;; 2: ADDR_DPT_LBA28 and 3: ADDR_DPT_LBA48             
-        ; Fall through to ConvertLCHStoLBARegisterValues  
-        
+;;; 2: ADDR_DPT_LBA28 and 3: ADDR_DPT_LBA48
+        ; Fall through to ConvertLCHStoLBARegisterValues
+
 ;---------------------------------------------------------------------
 ; Converts LCHS parameters to 28-bit LBA address.
@@ -129 +129 @@
     ; cylToSeek*headsPerCyl (18-bit result)
     mov     ax, cx                  ; Copy Cylinder number to AX
+    ; We could save a byte here by using CWD instead of the XOR DH, DH in eMOVZX
+    ; but I'm not sure how that would affect speed.
+
     eMOVZX  dx, BYTE [di+DPT.bLbaHeads]
     mul     dx                      ; DX:AX = cylToSeek*headsPerCyl