source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CompatibleDPT.asm@ 38

; File name     :   CompatibleDPT.asm
; Project name  :   IDE BIOS
; Created date  :   6.4.2010
; Last update   :   6.4.2010
; Author        :   Tomi Tilli
; Description   :   Functions for creating Disk Parameter Tables for
;                   software compatibility only. These DPTs are not used
;                   by our BIOS.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Creates compatible for drives 80h and 81h. There will be stored
; to interrupt vectors 41h and 46h.
;
; CompatibleDPT_CreateForDrives80hAnd81h
;   Parameters:
;       DS:     RAMVARS segment
;       ES:     BDA segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       All except DS and ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CompatibleDPT_CreateForDrives80hAnd81h:
    ; Only create compatible DPTs in full mode
    test    BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
    jz      SHORT CompatibleDPT_StoreCustomDPTs

    mov     dl, 80h
    call    FindDPT_ForDriveNumber  ; DPT to DS:DI
    jnc     SHORT .CreateForDrive81h
    call    CompatibleDPT_CreateForDrive80h
ALIGN JUMP_ALIGN
.CreateForDrive81h:
    mov     dl, 81h
    call    FindDPT_ForDriveNumber
    jnc     SHORT .Return
    call    CompatibleDPT_CreateForDrive81h
ALIGN JUMP_ALIGN
.Return:
    ret


;--------------------------------------------------------------------
; Stores pointers to our custom DPTs for drives 80h and 81h.
;
; CompatibleDPT_StoreCustomDPTs
;   Parameters:
;       ES:     BDA and interrupt vector segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       DX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CompatibleDPT_StoreCustomDPTs:
    mov     dl, 80h
    call    FindDPT_ForDriveNumber  ; DPT to DS:DI
    jnc     SHORT .FindForDrive81h
    mov     [es:INTV_HD0DPT*4], di
    mov     [es:INTV_HD0DPT*4+2], ds
ALIGN JUMP_ALIGN
.FindForDrive81h:
    inc     dx
    call    FindDPT_ForDriveNumber
    jnc     SHORT .Return
    mov     [es:INTV_HD1DPT*4], di
    mov     [es:INTV_HD1DPT*4+2], ds
ALIGN JUMP_ALIGN
.Return:
    ret


;--------------------------------------------------------------------
; Copies parameters from our custom DPT struct to a
; standard COMPATIBLE_FDPT or COMPATIBLE_EDPT struct.
;
; CompatibleDPT_CreateForDrive80h
; CompatibleDPT_CreateForDrive81h
;   Parameters:
;       DS:DI:  Ptr to DPT
;       ES:     BDA and interrupt vector segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CompatibleDPT_CreateForDrive80h:
    mov     si, FULLRAMVARS.drv80hCompDPT   ; DS:SI now points compatible DPT
    call    CompatibleDPT_CopyFromCustom
    mov     [es:INTV_HD0DPT*4], si
    mov     [es:INTV_HD0DPT*4+2], ds
    ret
ALIGN JUMP_ALIGN
CompatibleDPT_CreateForDrive81h:
    mov     si, FULLRAMVARS.drv81hCompDPT   ; DS:SI now points compatible DPT
    call    CompatibleDPT_CopyFromCustom
    mov     [es:INTV_HD1DPT*4], si
    mov     [es:INTV_HD1DPT*4+2], ds
    ret


;--------------------------------------------------------------------
; Copies parameters from our custom DPT struct to a
; standard COMPATIBLE_FDPT or COMPATIBLE_EDPT struct.
;
; CompatibleDPT_CopyFromCustom
;   Parameters:
;       DS:SI:  Ptr to COMPATIBLE_FDPT or COMPATIBLE_EDPT
;       DS:DI:  Ptr to DPT
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CompatibleDPT_CopyFromCustom:
    call    AccessDPT_GetLCHSfromPCHS           ; AX=Lsects, BX=Lcyls, DX=Lheads
    test    BYTE [di+DPT.bFlags], FLG_DPT_EBIOS ; Drive larger than 504 MiB?
    jnz     SHORT CompatibleDPT_CopyFromCustomToEDPT
    ; Fall to CompatibleDPT_CopyFromCustomToFDPT

;--------------------------------------------------------------------
; Copies parameters from our custom DPT struct to a
; standard COMPATIBLE_FDPT struct for drives up to 504 MiB.
;
; CompatibleDPT_CopyFromCustomToFDPT
;   Parameters:
;       AX:     L-CHS sectors per track
;       BX:     L-CHS cylinders
;       DX:     L-CHS heads
;       DS:SI:  Ptr to COMPATIBLE_FDPT
;       DS:DI:  Ptr to DPT
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX
;--------------------------------------------------------------------
;ALIGN JUMP_ALIGN
CompatibleDPT_CopyFromCustomToFDPT:
    mov     [si+COMPATIBLE_FDPT.wCyls], bx
    mov     [si+COMPATIBLE_FDPT.bHeads], dl
    mov     [si+COMPATIBLE_FDPT.bSectPerTrack], al
    mov     WORD [si+COMPATIBLE_FDPT.wWrPreCmpCyl], -1
    mov     al, [di+DPT.bDrvCtrl]
    mov     [si+COMPATIBLE_FDPT.bDrvCtrl], al
    mov     BYTE [si+COMPATIBLE_FDPT.bNormTimeout], B_TIMEOUT_BSY
    mov     BYTE [si+COMPATIBLE_FDPT.bFormatTimeout], B_TIMEOUT_DRQ
    mov     BYTE [si+COMPATIBLE_FDPT.bCheckTimeout], B_TIMEOUT_DRQ
    dec     bx
    mov     [si+COMPATIBLE_FDPT.wLZoneCyl], bx
    ret


;--------------------------------------------------------------------
; Copies parameters from our custom DPT struct to a
; standard COMPATIBLE_EDPT struct.
;
; CompatibleDPT_CopyFromCustomToEDPT
;   Parameters:
;       AX:     L-CHS sectors per track
;       BX:     L-CHS cylinders
;       DX:     L-CHS heads
;       DS:SI:  Ptr to COMPATIBLE_EDPT
;       DS:DI:  Ptr to DPT
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CompatibleDPT_CopyFromCustomToEDPT:
    mov     [si+COMPATIBLE_EDPT.wLCyls], bx
    mov     [si+COMPATIBLE_EDPT.bLHeads], dl
    mov     BYTE [si+COMPATIBLE_EDPT.bSignature], COMPATIBLE_EDPT_SIGNATURE
    mov     [si+COMPATIBLE_EDPT.bPSect], al
    mov     [si+COMPATIBLE_EDPT.bLSect], al
    mov     al, [di+DPT.bDrvCtrl]
    mov     [si+COMPATIBLE_EDPT.bDrvCtrl], al
    mov     ax, [di+DPT.wPCyls]
    mov     [si+COMPATIBLE_EDPT.wPCyls], ax
    mov     al, [di+DPT.bPHeads]
    mov     [si+COMPATIBLE_EDPT.bPHeads], al
    ; Fall to CompatibleDPT_StoreChecksum

;--------------------------------------------------------------------
; Stores checksum byte to the end of COMPATIBLE_EDPT struct.
;
; CompatibleDPT_StoreChecksum
;   Parameters:
;       DS:SI:  Ptr to COMPATIBLE_EDPT
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX
;--------------------------------------------------------------------
;ALIGN JUMP_ALIGN
CompatibleDPT_StoreChecksum:
    xor     ax, ax
    xor     bx, bx
    mov     cx, COMPATIBLE_EDPT_size-1
ALIGN JUMP_ALIGN
.SumLoop:
    add     al, [bx+si]
    inc     bx
    loop    .SumLoop
    neg     al
    mov     [si+COMPATIBLE_EDPT.bChecksum], al
    ret