Changeset 530 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/EBIOS

Timestamp:

Mar 28, 2013, 1:36:23 PM (12 years ago)

Author:

aitotat@…

google:author:

aitotat@gmail.com

Message:

Changes to XTIDE Universal BIOS:

• AT builds again copy old INT 13h handler to 40h. It turned out it is needed, by XTIDE Universal BIOS at least (fixes disappearing floppy drive hotkey button when booting starts).
• AH=48h no longer returns P-CHS parameteres for drives with more than 15,482,880 sectors (now works like described on Phoenix specification).

File:

• trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/EBIOS/AH48h_GetExtendedDriveParameters.asm (modified) (1 diff)

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

@@ -58 +58 @@
 .SkipEddConfigurationParameters:
     mov     [si+EDRIVE_INFO.wSize], cx
-    mov     WORD [si+EDRIVE_INFO.wFlags], FLG_DMA_BOUNDARY_ERRORS_HANDLED_BY_BIOS | FLG_CHS_INFORMATION_IS_VALID
+    mov     WORD [si+EDRIVE_INFO.wFlags], FLG_DMA_BOUNDARY_ERRORS_HANDLED_BY_BIOS
 
     ; Store total sector count
     mov     [si+EDRIVE_INFO.qwTotalSectors], ax
-    xor     ax, ax                                  ; Return with success
     mov     [si+EDRIVE_INFO.qwTotalSectors+2], dx
     mov     [si+EDRIVE_INFO.qwTotalSectors+4], bx
-    mov     [si+EDRIVE_INFO.qwTotalSectors+6], ax   ; Always zero
+    xor     cx, cx
+    mov     [si+EDRIVE_INFO.qwTotalSectors+6], cx   ; Always zero
     mov     WORD [si+EDRIVE_INFO.wSectorSize], 512
 
-    ; Store P-CHS
+    ; Store P-CHS. Based on phoenix specification this is returned only if
+    ; total sector count is 15,482,880 or less.
+    sub     ax, 4001h
+    sbb     dx, 0ECh
+    sbb     bx, cx      ; Zero
+    jnc     SHORT .ReturnWithSuccess    ; More than EC4000h
+    or      WORD [si+EDRIVE_INFO.wFlags], FLG_CHS_INFORMATION_IS_VALID
+
     eMOVZX  dx, BYTE [es:di+DPT.bPchsHeads]
-    xor     ax, ax                                  ; Also a return code
     mov     [si+EDRIVE_INFO.dwHeads], dx
-    mov     [si+EDRIVE_INFO.dwHeads+2], ax
+    mov     [si+EDRIVE_INFO.dwHeads+2], cx
 
     mov     dl, [es:di+DPT.bPchsSectorsPerTrack]
     mov     [si+EDRIVE_INFO.dwSectorsPerTrack], dx
-    mov     [si+EDRIVE_INFO.dwSectorsPerTrack+2], ax
+    mov     [si+EDRIVE_INFO.dwSectorsPerTrack+2], cx
 
     mov     dx, [es:di+DPT.wPchsCylinders]
     mov     [si+EDRIVE_INFO.dwCylinders], dx
-    mov     [si+EDRIVE_INFO.dwCylinders+2], ax
+    mov     [si+EDRIVE_INFO.dwCylinders+2], cx
 
+.ReturnWithSuccess:
+    xor     ax, ax
 .ReturnWithError:
     jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH