Changeset 95 for trunk/bootcode/regular/driveio.asm

Timestamp:

Apr 8, 2017, 12:26:39 AM (8 years ago)

Author:

Ben Rietbroek

Message:

Moved 'CheckFor13extensions' to module 'driveio' [v1.1.1-testing]

CAUTION:
This is a testbuild !
AirBoot uses the BIOS to access disks and a small coding error can trash
partition tables or other vital disk structures. You are advised to make
backups of TRACK0 and EBRs before using this testbuild. More info at:
​https://rousseaux.github.io/netlabs.air-boot/pdf/AirBoot-v1.1.0-manual.pdf

File:

• trunk/bootcode/regular/driveio.asm (modified) (1 diff)

trunk/bootcode/regular/driveio.asm

@@ -25 +25 @@
 DB 'DRIVEIO',0
 ENDIF
+
+;
+; Check if INT13X extensions are supported.
+; AirBoot requires these extensions, and will halt if they are not available.
+; Modified: AX, BX, CX, DX, CF
+DriveIO_CheckFor13extensions    Proc Near
+        mov     ah, 41h
+        mov     bx, 55AAh
+        mov     dl, [BIOS_BootDisk]     ; We check using the boot-disk
+        int     13h
+        jc      PCCF13E_NotFound        ; Error occured
+        cmp     bx, 0AA55h
+        je      PCCF13E_Found
+    PCCF13E_NotFound:
+        ret
+    PCCF13E_Found:
+        and     cx, 1                   ; Check 42h-44h,47h,48h supported
+        jz      PCCF13E_NotFound        ; Sig OK but no support, strange beast
+        mov     byte ptr [CurIO_UseExtension], 1
+        ret
+DriveIO_CheckFor13extensions    EndP
+
 
 ; Note: Some routines set DS/ES to CS or even address via CS, even if its not