source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm@ 285

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for detecting drive for the BIOS.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Detects all IDE hard disks to be controlled by this BIOS.
;
; DetectDrives_FromAllIDEControllers
;   Parameters:
;       DS:     RAMVARS segment
;       ES:     BDA segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       All (not segments)
;--------------------------------------------------------------------
DetectDrives_FromAllIDEControllers:
    call    RamVars_GetIdeControllerCountToCX
    mov     bp, ROMVARS.ideVars0            ; CS:BP now points to first IDEVARS

.DriveDetectLoop:                           ; Loop through IDEVARS
    push    cx

    mov     cx, g_szDetectMaster
    mov     bh, MASK_DRVNHEAD_SET                               ; Select Master drive
    call    StartDetectionWithDriveSelectByteInBHandStringInAX  ; Detect and create DPT + BOOTNFO

    mov     cx, g_szDetectSlave
    mov     bh, MASK_DRVNHEAD_SET | FLG_DRVNHEAD_DRV
    call    StartDetectionWithDriveSelectByteInBHandStringInAX

    pop     cx

    add     bp, BYTE IDEVARS_size           ; Point to next IDEVARS

%ifdef MODULE_SERIAL
    jcxz    .AddHardDisks                   ; Set to zero on .ideVarsSerialAuto iteration (if any)
%endif

    loop    .DriveDetectLoop

%ifdef MODULE_SERIAL
;----------------------------------------------------------------------
;
; if serial drive detected, do not scan (avoids duplicate drives and isn't needed - we already have a connection)
;
    call    FindDPT_ToDSDIforSerialDevice
    jnc     .AddHardDisks

    mov     bp, ROMVARS.ideVarsSerialAuto   ; Point to our special IDEVARS structure, just for serial scans

    mov     al,[cs:ROMVARS.wFlags]          ; Configurator set to always scan?
    or      al,[es:BDA.bKBFlgs1]            ; Or, did the user hold down the ALT key?
    and     al,8                            ; 8 = alt key depressed, same as FLG_ROMVARS_SERIAL_ALWAYSDETECT
    jnz     .DriveDetectLoop
%endif

.AddHardDisks:
;----------------------------------------------------------------------
;
; Add in hard disks to BDA, finalize our Count and First variables
;
; Note that we perform the add to bHDCount and store bFirstDrv even if the count is zero.
; This is done because we use the value of .bFirstDrv to know how many drives were in the system
; at the time of boot, and to return that number on int13h/8h calls.  Because the count is zero,
; FindDPT_ForDriveNumber will not find any drives that are ours.
;
    mov     cx, [RAMVARS.wDrvCntAndFlopCnt]     ; Our count of hard disks

    mov     al, [es:BDA.bHDCount]
    add     cl, al                      ; Add our drives to the system count
    mov     [es:BDA.bHDCount], cl       
    or      al, 80h                     ; Or in hard disk flag      
    mov     [RAMVARS.bFirstDrv], al     ; Store first drive number      

.AddFloppies:       
%ifdef MODULE_SERIAL_FLOPPY     
;----------------------------------------------------------------------
;
; Add in any emulated serial floppy drives, finalize our packed Count and First variables
;
    dec     ch
    mov     al, ch
    js      .NoFloppies                     ; if no drives are present, we store 0ffh       

    call    FloppyDrive_GetCountFromBIOS_or_BDA

    push    ax

    add     al, ch                          ; Add our drives to existing drive count
    cmp     al, 3                           ; For BDA, max out at 4 drives (ours is zero based)
    jl      .MaxBDAFloppiesExceeded
    mov     al, 3                           
.MaxBDAFloppiesExceeded:
    eROR_IM al, 2                           ; move to bits 6-7
    inc     ax                              ; low order bit, indicating floppy drive exists

    mov     ah, [es:BDA.wEquipment]         ; Load Equipment WORD low byte  
    and     ah, 03eh                        ; Mask off drive number and drives present bit
    or      al, ah                          ; Or in new values
    mov     [es:BDA.wEquipment], al         ; and store

    mov     al, 1eh                         ; BDA pointer to Floppy DPT
    mov     si, AH8h_FloppyDPT
    call    Interrupts_InstallHandlerToVectorInALFromCSSI

    pop     ax

    shr     ch, 1                           ; number of drives, 1 or 2 only, to CF flag (clear=1, set=2)
    rcl     al, 1                           ; starting drive number in upper 7 bits, number of drives in low bit
.NoFloppies:    
    mov     [RAMVARS.xlateVars+XLATEVARS.bFlopCntAndFirst], al
%endif
        
    ret

%ifndef CHECK_FOR_UNUSED_ENTRYPOINTS        
    %if FLG_ROMVARS_SERIAL_SCANDETECT != 8
        %error "DetectDrives is currently coded to assume that FLG_ROMVARS_SERIAL_SCANDETECT is the same bit as the ALT key code in the BDA.  Changes in the code will be needed if these values are no longer the same."
    %endif
%endif


;--------------------------------------------------------------------
; StartDetectionWithDriveSelectByteInBHandStringInAX
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       CX:     Offset to "Master" or "Slave" string
;       CS:BP:  Ptr to IDEVARS for the drive
;       DS:     RAMVARS segment
;       ES:     Zero (BDA segment)
;   Returns:
;       None
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
StartDetectionWithDriveSelectByteInBHandStringInAX:
    call    DetectPrint_StartDetectWithMasterOrSlaveStringInAXandIdeVarsInCSBP
    ; Fall to .ReadAtaInfoFromHardDisk

;--------------------------------------------------------------------
; .ReadAtaInfoFromHardDisk
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       CS:BP:  Ptr to IDEVARS for the drive
;       DS:     RAMVARS segment
;       ES:     Zero (BDA segment)
;   Returns:
;       CF:     Cleared if ATA-information read successfully
;               Set if any error
;   Corrupts registers:
;       AX, BL, CX, DX, SI, DI
;--------------------------------------------------------------------
.ReadAtaInfoFromHardDisk:
    mov     si, BOOTVARS.rgbAtaInfo     ; ES:SI now points to ATA info location
    push    es
    push    si
    push    bx
    call    Device_IdentifyToBufferInESSIwithDriveSelectByteInBH
    pop     bx
    pop     si
    pop     es
    jnc     SHORT CreateBiosTablesForHardDisk
    ; Fall to .ReadAtapiInfoFromDrive

.ReadAtapiInfoFromDrive:                ; Not yet implemented
    ;call   ReadAtapiInfoFromDrive      ; Assume CD-ROM
    ;jnc    SHORT _CreateBiosTablesForCDROM

    ;jmp    short DetectDrives_DriveNotFound
;;; fall-through instead of previous jmp instruction
;--------------------------------------------------------------------
; DetectDrives_DriveNotFound
;   Parameters:
;       Nothing
;   Returns:
;       CF:     Set (from BootMenuPrint_NullTerminatedStringFromCSSIandSetCF)
;   Corrupts registers:
;       AX, SI
;--------------------------------------------------------------------
DetectDrives_DriveNotFound:
    mov     si, g_szNotFound
    jmp     BootMenuPrint_NullTerminatedStringFromCSSIandSetCF


;--------------------------------------------------------------------
; CreateBiosTablesForHardDisk
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       CS:BP:  Ptr to IDEVARS for the drive
;       ES:SI   Ptr to ATA information for the drive
;       DS:     RAMVARS segment
;       ES:     BDA/Bootnfo segment
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
CreateBiosTablesForHardDisk:
    call    CreateDPT_FromAtaInformation
    jc      SHORT DetectDrives_DriveNotFound
    call    BootMenuInfo_CreateForHardDisk
    jmp     short DetectPrint_DriveNameFromBootnfoInESBX