;::::::::::::::::::::::::::::::::::::::::::::::::**************************
; Hard disk routines as implemented for		 **  Hardware Dependent  **
;  SIMH Altair80				 ** for exact interface  **
;  D-X Designs Pty Ltd P112.			 **************************
;--------------------------------------------------------------------------
; This file uses modifications of the definitions in ICFG-xx to reflect
; Physical and/or logical definitions for HBIOS drives.  A controller type of
; 8xH signifies IDE/ATA drives, in which case the Drive byte at HDRVx is:
;	7 6 5 4 3 2 1 0
;	| | | | | | | +- Unit Number (0 = Master, 1 = Slave)
;	| | | | +-+-+---  (reserved)
;	| | | +--------- 1 = Active, 0 = Inactive
;	+-+-+-----------  (reserved)
; Additionally, the first byte of the Reduced Write Cylinder word is re-
; defined to be the number of physical/logical Sectors-Per-Track.
;   These parameters are used to convert the Track & 16 Sector/Track format
; assumed in the B/P Bios definitions for Hard Drives into Track/Sector/Head
; Sector Number needed for IDE/ATA Data accesses.  Direct driver IO routines
; to Select (SELHD), Read (HDREAD) and Write (HDWRIT) are all included here.
;--------------------------------------------------------------------------
; 1.0 - 26 Aug 01 - Cleaned up source and included fixes from SCSI.	HFB
; 0.2 - 28 Jun 97 - Added Home Drive, Retry Disable bit handling.	HFB
; 0.1 - 25 Apr 97 - Initial Test Release				HFB
;***************************************************************************

	  IF  BANKED
	COMMON	/BANK2/
	  ELSE
	CSEG
	  ENDIF

;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; Function 0 - Set User Data Area Adress for Direct Disk IO, Return
;		Number of Bytes in the driver Command Block (SCSI-"like")
;   For IDE, a minimum of 6 Bytes is needed (Comnd,Trk(2),Sctr,Head,Drive)
; Enter: DE = Address of User Data Area
; Exit :  A = Number of bytes available in the Command Block
; Uses : A,HL
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

HDVALS:	CALL	PANIC		; NOT IMPLEMENTED!!!!
	RET

;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; Function 1 - Set Drive bit Command Block from A
; Enter:  A = Drive Byte
; Exit :  A = Drive Bit in LSB (00/01H, for Master/Slave)
; Uses : AF
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

HDSLCT:	CALL	PANIC		; NOT IMPLEMENTED!!!!
	RET

;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; Function 2 - Direct SCSI driver.  This routine performs the function
;  described by the command in the HD Command Block with Data area
;  addressed by DE.  At the end of the function, 512 bytes of data are
;  transferred from the Bios IO Buffer to the Users Space set by Fcn 0.
;
; Enter: DE = Pointer to User Command Descriptor Block
;		HDCOMD contains pre-filled SCSI Command Block
;	  A = 0 if No Data to be Written, FF if User-supplied data to write
; Exit :  H = Message Byte value
;	  L = Status Byte value
;	  A = Status byte, Flags set accordingly.
; Uses : AF,BC,DE,HL
; NOTE : Routine assumes the Command Block is properly configured for the
;	desired function and device.  Errors in phasing result in program
;	exit and Warm Boot function, while Timeout returns 0FFH.
; For external access, It assumes the user has used Functions 0 and 1 to
; set the data transfer source/dest address and logical & physical drive.
;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

HD_RW:	CALL	PANIC		; NOT IMPLEMENTED!!!!
	RET

;========================================================================
; Select Hard Disk (Unit 0/1, Master/Slave)	< Internal Bios routine >

SELHD:	; SET DEVICE

;	CALL	PRTSTRD
;	DEFB	'[SELHD]$'

	JP	SETPARMS	;   then set parameters for DPH/DPB

;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; Write to Hard Disk Drive			< Internal BIOS Routine >
;  Writes from HSTBUF using HSTTRK and HSTSEC to build Block Number.
; NOTE: This routine uses physical drive characteristics from ICFG-xx.

HDWRIT:	

	XOR	A
	LD	(HSTWRT),A	; Show no active writes pending

	JP	HDSK_WRITE	; ..continue

;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; Read from Hard Disk Drive			< Internal BIOS Routine >
;  Reads to HSTBUF using HSTTRK and HSTSEC to build Block Number.
; NOTE: This routine uses physical drive characteristics from ICFG-xx.
; The routine computes a sequential block number (as with SCSI) with
; the algorithm; Trk * 16 + Sector, then computes Head, Sector and Track
; using Physical characteristics (hdHds = Number_of_Heads,
; hdSPT = Sectors_per_Track) according to the algorithm:
;
;   Sector := (Block# MOD hdSPT)+1	(* Quotient1 := Block# DIV hdSPT *)
;   Head   := Quotient1 MOD hdHds	(* Quotient2 := Quotient1 DIV hdHds *)
;   Track  := Quotient2

HDREAD:
	JP	HDSK_READ

	  IF  BANKED
	COMMON	/B2RAM/
	  ELSE
	DSEG
	  ENDIF

;======================= End of HARDIDE ===========================


	  IF  BANKED
	COMMON	/BANK2/
	  ELSE
	CSEG
	  ENDIF

;
;==================================================================================================
;   HDSK DISK DRIVER
;==================================================================================================
;
; IO PORT ADDRESSES
;
HDSK_IO		EQU	0FDH
;
HDSK_CMDNONE	EQU	0
HDSK_CMDRESET	EQU	1
HDSK_CMDREAD	EQU	2
HDSK_CMDWRITE	EQU	3
HDSK_CMDPARAM	EQU	4
;
; STATUS
;
HDSKRC_OK	EQU	0
;
;
;
HDSK_READ:
;	CALL	PRTSTRD
;	DEFB	'[HDSK READ]$'

	LD	B,13H		; $13 IS HBIOS DISK READ
	JR	HDSK_RW
;
;
;
HDSK_WRITE:
;	CALL	PRTSTRD
;	DEFB	'[HDSK WRITE]$'

	LD	B,14H		; $14 IS HBIOS DISK WRITE
	JR	HDSK_RW
;
;
;
HDSK_RW:
	LD	HL,(HSTDPH)	; GET ACTIVE DPH POINTER
	DEC	HL		; ADJUST TO POINT TO UNIT NUMBER
	LD	C,(HL)		; LOAD IT IN C FOR HBIOS CALL LATER
	PUSH	BC		; SAVE FUNCTION AND DEVICE FOR LATER
	LD	HL,(HSTTRK)	; GET TRACK VALUE
	LD	A,L		; LSB OF TRACK TO A
	AND	0FH		; ISOLATE HEAD IN LOW 4 BITS
	LD	D,A		; STUFF IT IN D
	LD	A,(HSTSEC)	; GET SECTOR
	LD	E,A		; STUFF IT IN E
	LD	B,4		; PREPARE TO SHIFT OUT 4 BIT HEAD VALUE
HDSK_RW1:                       
	SRL	H		; SHIFT ONE BIT OUT
	RR	L		; ... OF HL
	DJNZ	HDSK_RW1	; DO ALL 4 BITS
	POP	BC		; RECOVER FUNCTION AND DEVICE
	PUSH	BC		; SAVE INCOMING FUNCTION, DEVICE/UNIT
	LD	B,12H		; SETUP FOR NEW SEEK CALL
	CALL	HBX_INVOKE	; DO IT
	POP	BC              ; RESTORE INCOMING FUNCTION, DEVICE/UNIT
	RET	NZ              ; ABORT IF SEEK RETURNED AN ERROR W/ ERROR IN A
	LD	HL,(HB_DSKBUF)  ; GET BUFFER ADDRESS
	LD	DE,1            ; TRANSFER ONE SECTOR
	CALL	HBX_INVOKE	; DO IT
	OR	A		; SET FLAGS
	RET	Z		; DONE IF NO ERROR

	OR	0FFH		; A=$FF TO SIGNAL ERROR
	RET			; AND DONE W/ ERROR
;
;==================================================================================================
;   HDSK DISK DRIVER - DATA
;==================================================================================================
;
	  IF  BANKED
	COMMON	/B2RAM/
	  ELSE
	DSEG
	  ENDIF

	  
HDSK_PDN	DEFS	1		; PHYSICAL DEVICE