source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH8h_HParams.asm@ 280

; Project name  :   XTIDE Universal BIOS
; Description   :   Int 13h function AH=8h, Read Disk Drive Parameters.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=8h, Read Disk Drive Parameters.
;
; AH8h_HandlerForReadDiskDriveParameters
;   Parameters:
;       DL:     Translated Drive number
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Returns with INTPACK:
;       BL:     Drive Type (for floppies only)
;       CH:     Maximum cylinder number, bits 7...0
;       CL:     Bits 7...6: Cylinder number bits 9...8
;               Bits 5...0: Maximum sector number (1...63)
;       DH:     Maximum head number (0...255)
;       DL:     Number of drives
;       ES:DI:  Floppy DPT (for floppies only)
;       AH:     Int 13h/40h floppy return status
;       CF:     0 if successfull, 1 if error
;--------------------------------------------------------------------
AH8h_HandlerForReadDiskDriveParameters:
    test    di,di
    jnz     SHORT .OurDrive

    call    Int13h_CallPreviousInt13hHandler
    jnc     SHORT .MidGame
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
        
.OurDrive:      
    call    AH8h_GetDriveParameters

%ifdef MODULE_SERIAL_FLOPPY
    push    cs                          ; setup registers if we are a floppy drive, in all cases
    pop     es                          ; if it is not a floppy drive, these values will not be put in INTPACK
    mov     di, AH8h_FloppyDPT
%endif
    ;; fall-through
        
.MidGame:       
    call    RamVars_GetCountOfKnownDrivesToAX       ; assume hard disk for now, will discard if for floppies

    test    byte [bp+IDEPACK.intpack+INTPACK.dl], 080h
    jnz     .Done
        
    mov     [bp+IDEPACK.intpack+INTPACK.bl], bl

    mov     [bp+IDEPACK.intpack+INTPACK.es], es
    mov     [bp+IDEPACK.intpack+INTPACK.di], di     

    call    FloppyDrive_GetCountToAX

.Done:  
    mov     ah, dh
        
    mov     [bp+IDEPACK.intpack+INTPACK.cx], cx
    xchg    [bp+IDEPACK.intpack+INTPACK.dx], ax     ; recover DL for BDA last status byte determination

    xor     ah, ah
%ifdef MODULE_SERIAL_FLOPPY
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH_ALHasDriveNumber            
%else
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
%endif


;--------------------------------------------------------------------
; Returns L-CHS parameters for drive and total hard disk count.
;
; AH8h_GetDriveParameters
;   Parameters:
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;   Returns:
;       CH:     Maximum cylinder number, bits 7...0
;       CL:     Bits 7...6: Cylinder number bits 9...8
;               Bits 5...0: Maximum sector number (1...63)
;       DH:     Maximum head number (0...255)
;   Corrupts registers:
;       AX, BX
;--------------------------------------------------------------------
AH8h_GetDriveParameters:
    call    AccessDPT_GetLCHStoAXBLBH
    ; Fall to .PackReturnValues

;--------------------------------------------------------------------
; Packs L-CHS values to INT 13h, AH=08h return values.
;
; .PackReturnValues
;   Parameters:
;       AX:     Number of L-CHS cylinders available (1...1024)
;       BL:     Number of L-CHS heads (1...256)
;       BH:     Number of L-CHS sectors per track (1...63)
;       DS:     RAMVARS segment
;   Returns:
;       CH:     Maximum cylinder number, bits 7...0
;       CL:     Bits 7...6: Cylinder number bits 9...8
;               Bits 5...0: Maximum sector number (1...63)
;       DH:     Maximum head number (0...255)
;   Corrupts registers:
;       AX, BX
;--------------------------------------------------------------------
.PackReturnValues:
    dec     ax                      ; AX = Number of last cylinder
    dec     bx                      ; BL = Number of last head
    xchg    cx, ax
    xchg    cl, ch                  ; CH = Last cylinder bits 0...7
    eROR_IM cl, 2                   ; CL bits 6...7 = Last cylinder bits 8...9
    or      cl, bh                  ; CL bits 0...5 = Sectors per track
    mov     dh, bl                  ; DH = Maximum head number
        
%ifdef MODULE_SERIAL_FLOPPY
    mov     bl,[di+DPT.bFlagsHigh]
%ifndef CHECK_FOR_UNUSED_ENTRYPOINTS             ; not sure why this is needed for preprocessor-only
    eSHR_IM bl,FLGH_DPT_SERIAL_FLOPPY_TYPE_FIELD_POSITION
%endif
%endif      
    ret

%ifdef MODULE_SERIAL_FLOPPY
;
; Floppy Disk Parameter Table.  There is no way to specify more than one of these
; for any given system, so no way to make this drive or media specific.
; So we return fixed values out of the ROM for callers who might be expecting this information.
;
; On AT systems, we return the information for a 1.44 MB disk, 
; and on XT systems, we return the information for a 360 KB disk.
;
AH8h_FloppyDPT:
%ifdef USE_AT
    db      0ah << 4 | 0fh          ; Offset 0: Drive timings, 1.44MB values
%else
    db      0dh << 4 | 0fh          ; Offset 0: Drive timings, 360KB values
%endif

    db      1h << 1 | 0             ; Offset 1: Typical values of 1 for head load time
                                    ;           DMA used (although it actually is not, but is more restrctive)
    db      25h                     ; Offset 2: Inactiviy motor turn-off delay, 
                                    ;           Typical value of 25h for 2 second delay
    db      02h                     ; Offset 3: Sector size, always 512

%ifdef USE_AT
    db      12h                     ; Offset 4: Sectors per track, 1.44MB value
    db      1bh                     ; Offset 5: Sector gap, 1.44MB value
%else
    db      09h                     ; Offset 4: Sectors per track, 360KB value
    db      2ah                     ; Offset 5: Sector gap, 360KB value
%endif

    db      0ffh                    ; Offset 6: Data length

%ifdef USE_AT
    db      6ch                     ; Offset 7: Format gap length, 1.44MB value
%else
    db      50h                     ; Offset 7: Format gap length, 360KB value
%endif

    db      0f6h                    ; Offset 8: Fill byte for format
    db      0fh                     ; Offset 9: Head setting time
    db      08h                     ; Offset A: Wait for motor startpu time

%ifdef USE_AT
    db      79                      ; Offset B: Maximum track number, 1.44MB value
    db      0                       ; Offset C: Data transfer rate, 1.44MB value
    db      4                       ; Offset D: Diskette CMOS drive type, 1.44MB value
%else
    db      39                      ; Offset B: Maximum track number, 360KB value
    db      80h                     ; Offset C: Data transfer rate, 360KB value
    db      1                       ; Offset D: Diskette CMOS drive type, 360KB value
%endif
%endif