source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/Tools/Prepare.asm@ 590

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for preparing data buffer for transfer.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Prepare_ByLoadingDapToESSIandVerifyingForTransfer
;   Parameters:
;       SI:     Offset to DAP
;       DS:DI:  Ptr to DPT
;       SS:BP:  Ptr to IDEPACK
;   Parameters on INTPACK:
;       DS:SI:  Ptr to Disk Address Packet
;   Returns:
;       BX:     Index to command lookup table
;       ES:SI:  Ptr to Disk Address Packet (DAP)
;       Exits from INT 13h if invalid DAP
;   Corrupts registers:
;       AX, DX
;--------------------------------------------------------------------
%ifdef MODULE_EBIOS
ALIGN JUMP_ALIGN
Prepare_ByLoadingDapToESSIandVerifyingForTransfer:
    ; Load pointer to DAP to ES:SI and make sure it is valid
    mov     es, [bp+IDEPACK.intpack+INTPACK.ds] ; ES:SI to point Disk Address Packet
    cmp     BYTE [es:si+DAP.bSize], MINIMUM_DAP_SIZE
    jb      SHORT InvalidDAP

    ; Make sure that sector count is valid
%ifdef USE_UNDOC_INTEL
    salc    ; Clear AL using CF (CF is cleared since JB above fell through)
    or      al, [es:si+DAP.wSectorCount]
%else
    mov     al, [es:si+DAP.wSectorCount]
    test    al, al
%endif
    jz      SHORT ZeroSectorsRequestedSoNoErrors
    js      SHORT InvalidNumberOfSectorsRequested

%if 0   ; Slow version in the unlikely case that high byte needs to be checked.
    mov     ax, [es:si+DAP.wSectorCount]
    test    ax, ax
    jz      SHORT ZeroSectorsRequestedSoNoErrors
    cmp     ax, BYTE 127
    ja      SHORT InvalidNumberOfSectorsRequested
%endif

    ; Get EBIOS command index to BX
    ; LBA28 or LBA48 command
    call    Prepare_GetOldInt13hCommandIndexToBX
    mov     al, [di+DPT.bFlagsLow]
    eSHL_IM al, 1                   ; Set CF if LBA48 supported
    adc     bl, bh                  ; LBA48 EXT commands
    ret
%endif ; MODULE_EBIOS


;--------------------------------------------------------------------
; Prepare_GetOldInt13hCommandIndexToBX
;   Parameters:
;       DS:DI:  Ptr to DPT
;   Returns:
;       BX:     Index to command lookup table
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Prepare_GetOldInt13hCommandIndexToBX:
    ; Block mode or single sector
    mov     bl, [di+DPT.bFlagsHigh]
    and     bx, BYTE FLGH_DPT_USE_BLOCK_MODE_COMMANDS   ; Bit 1
    ret


;---------------------------------------------------------------------
; Prepare_BufferToESSIforOldInt13hTransfer
;   Parameters:
;       AL:     Number of sectors to transfer
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Parameters on INTPACK:
;       ES:BX:  Ptr to data buffer
;   Returns:
;       ES:SI:  Ptr to normalized data buffer
;       Exits INT 13h if error
;   Corrupts registers:
;       BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Prepare_BufferToESSIforOldInt13hTransfer:
    mov     si, [bp+IDEPACK.intpack+INTPACK.bx] ; Load offset
    mov     es, [bp+IDEPACK.intpack+INTPACK.es] ; Load segment
    ; Fall to Prepare_ByValidatingSectorsInALforOldInt13h

;---------------------------------------------------------------------
; Prepare_ByValidatingSectorsInALforOldInt13h
;   Parameters:
;       AL:     Number of sectors to transfer (1...128 is valid)
;   Returns:
;       Exits INT 13h if invalid number of sectors in AL
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
Prepare_ByValidatingSectorsInALforOldInt13h:
    test    al, al                              ; Check if 0 < AL < 128 (Clears OF)
    jle     SHORT .CheckIf128Sectors            ; Jump if not
    ret     ; Continue with transfer

ALIGN JUMP_ALIGN
.CheckIf128Sectors:
    cmp     al, 128
    jne     SHORT InvalidNumberOfSectorsRequested
    test    si, si                              ; Offset must be zero to xfer 128 sectors
    jnz     SHORT CannotAlignPointerProperly
    ret     ; Continue with transfer

InvalidDAP:
InvalidNumberOfSectorsRequested:
Prepare_ReturnFromInt13hWithInvalidFunctionError:
    mov     ah, RET_HD_INVALID
    SKIP2B  f
CannotAlignPointerProperly:
    mov     ah, RET_HD_BOUNDARY
ZeroSectorsRequestedSoNoErrors:
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH



; Command lookup tables
g_rgbReadCommandLookup:
    db      COMMAND_READ_SECTORS        ; 00b, CHS or LBA28 single sector
    db      COMMAND_READ_SECTORS_EXT    ; 01b, LBA48 single sector
    db      COMMAND_READ_MULTIPLE       ; 10b, CHS or LBA28 block mode
%ifdef MODULE_EBIOS
    db      COMMAND_READ_MULTIPLE_EXT   ; 11b, LBA48 block mode
%endif

g_rgbWriteCommandLookup:
    db      COMMAND_WRITE_SECTORS
    db      COMMAND_WRITE_SECTORS_EXT
    db      COMMAND_WRITE_MULTIPLE
%ifdef MODULE_EBIOS
    db      COMMAND_WRITE_MULTIPLE_EXT
%endif

g_rgbVerifyCommandLookup:
    db      COMMAND_VERIFY_SECTORS
    db      COMMAND_VERIFY_SECTORS_EXT
    db      COMMAND_VERIFY_SECTORS
%ifdef MODULE_EBIOS
    db      COMMAND_VERIFY_SECTORS_EXT
%endif