source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Inc/CustomDPT.inc@ 198

; Project name  :   XTIDE Universal BIOS
; Description   :   Defines for DPT structs containing custom
;                   Disk Parameter Table used by this BIOS.
%ifndef CUSTOMDPT_INC
%define CUSTOMDPT_INC

; Base DPT for all device types
struc DPT   ; 10 bytes
    ; General Disk Parameter Table related
    .wFlags:
    .bFlagsLow                  resb    1
    .bFlagsHigh                 resb    1
    .bIdevarsOffset             resb    1   ; Offset to IDEVARS for this drive
%ifdef MODULE_SERIAL
    .bSerialPortAndBaud         resb    1   ; Packed I/O port and baud rate for serial drives
%else
                                resb    1   ; without serial port support, alignment byte
%endif

    ; IDE Drive related
    .dwCylinders                resb    4   ; Number of Cylinders
    .wHeadsAndSectors:
    .bHeads                     resb    1   ; Number of Heads (1...255)
    .bSectors                   resb    1   ; Number of Sectors per Track (1...63)
endstruc

; DPT for ATA devices
struc DPT_ATA   ; 10 + 2 bytes = 12 bytes
    .dpt                        resb    DPT_size

    ; Block size is specified in sectors (1, 2, 4, 8, 16, 32 or 64).
    ; 128 is not allowed to prevent offset overflow during data transfer.
    .wSetAndMaxBlock:
    .bSetBlock                  resb    1   ; Current block size (at least 1)
    .bMaxBlock                  resb    1   ; Maximum block size, 0 = block mode not supported
endstruc

LARGEST_DPT_SIZE                EQU     DPT_ATA_size


; Bit definitions for DPT.bFlagsLow
MASKL_DPT_CHS_SHIFT_COUNT       EQU (7<<0)  ; Bits 0...3, P-CHS to L-CHS bit shift count (0...4)
FLGL_DPT_SLAVE                  EQU FLG_DRVNHEAD_DRV    ; (1<<4), Drive is slave drive
MASKL_DPT_ADDRESSING_MODE       EQU (3<<5)  ; Bits 5..6, Addressing Mode (bit 6 == FLG_DRVNHEAD_LBA)
FLGL_DPT_ENABLE_IRQ             EQU (1<<7)

; Bit definitions for DPT.bFlagsHigh
FLGH_DPT_REVERSED_A0_AND_A3     EQU (1<<0)  ; XTIDE mod, Address lines 0 and 3 reversed
FLGH_DPT_BLOCK_MODE_SUPPORTED   EQU (1<<1)  ; Use block transfer commands (must be bit 1!)
%ifdef MODULE_SERIAL
FLGH_DPT_SERIAL_DEVICE          EQU (1<<2)  ; Serial Port Device
%endif
FLGH_DPT_INTERRUPT_IN_SERVICE   EQU (1<<3)  ; Set when waiting for IRQ
FLGH_DPT_RESET_nDRDY            EQU (1<<4)  ; Drive ready to accept commands
FLGH_DPT_RESET_nINITPRMS        EQU (1<<5)  ; Initialize Device Parameters successfull
FLGH_DPT_RESET_nRECALIBRATE     EQU (1<<6)  ; Recalibrate successfull
FLGH_DPT_RESET_nSETBLOCK        EQU (1<<7)  ; Initialize Block Mode successfull
MASKH_DPT_RESET                 EQU 0F0h

; Addressing modes for DPT.wFlags
ADDRESSING_MODE_FIELD_POSITION  EQU     5
ADDRESSING_MODE_LCHS            EQU     0   ; L-CHS Addressing Mode (NORMAL in many other BIOSes)
ADDRESSING_MODE_PCHS            EQU     1   ; P-CHS Addressing Mode (LARGE in many other BIOSes)
ADDRESSING_MODE_LBA28           EQU     2   ; 28-bit LBA Addressing Mode
ADDRESSING_MODE_LBA48           EQU     3   ; 48-bit LBA Addressing Mode

%macro CustomDPT_GetUnshiftedAddressModeToALZF 0
    mov     al, [di+DPT.bFlagsLow]
    and     al, MASKL_DPT_ADDRESSING_MODE
%endmacro

; Number of Sectors per Track is fixed to 63 for LBA assist calculation.
; 1024 cylinders, 256 heads, 63 sectors = 8.4 GB limit (but DOS does not support more than 255 heads)
MAX_LCHS_CYLINDERS              EQU     1024
LBA_ASSIST_SPT                  EQU     63


%endif ; CUSTOMDPT_INC