RomWBW/Source/BPBIOS/floppy.z80

;**************************************************************************
;    Hardware  Independent  Floppy  Drive  Routines
;
; This module uses information from HSTDPH/HSTDPB and other HST values to
; access Floppy drives.  It establishes physical parameters, performs
; logical to physical mapping of Track/Sector/Head information and links
; to Physical Read/Write routines in module FDC-xx.
;
; 1.4 - 23 Aug 01 - Cleaned up for GPL release.				HFB
; 1.3 -  6 Aug 95 - Mod to handle Kaypro4 (Double-sided, continuous
;		Sector #s w/Head = 0 on both side's Gap records.	HFB
;  7 Jan 95 - Correct calcs for reversed Side 1 (Ken Owen fix)		HFB
;  3 Jul 92 - First General Release.					HFB
;  8 Jul 91 - Initial test release					HFB
;**************************************************************************

	  IF  BANKED
	COMMON	/BANK2/
	  ELSE
	CSEG
	  ENDIF

;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
;			Read/Write  Host  Buffer
;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; Physical Write of "HSTSIZ" bytes from HSTBUF.  Return Error Flag in ERFLAG
; and in Registers AF.  This routine assumes that parameters are set as:
;   HSTDSK = Host Disk #, HSTTRK = Host Track #, HSTSEC = Host Sect #.

FWRITE:	XOR	A		; Get Write Clear value & RDOP Write Value
	LD	(HSTWRT),A	;  say there is no pending Write
	JR	FRWHST		;   and link with common code below

; Physical Read of "HSTSIZ" bytes from HSTBUF.  Return Error Flag in ERFLAG
; and in Registers AF.  This routine assumes that parameters are set as:
;   HSTDSK = Host Disk #, HSTTRK = Host Track #, HSTSEC = Host Sect #.

FREAD:	LD	A,1		; Set Read Value for RDOP

; Linkage to FDC Dependent routines

FRWHST:	LD	(RDOP),A
	CALL	FSETHD		; Sort out track, sector, and head
	JP	FHDRW		; Jump to hardware dependent r/w code

	PAGE
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
; FSETHD - Routine to set the Head Number, Sector and Track for FDC
;  Operation.  This routine uses the "HST" values and DPH in order to
;  set things up.  This routine is Hardware Independent.
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

	  IF  BANKED
	COMMON	/BANK2/
	  ELSE
	CSEG
	  ENDIF

FSETHD:	LD	C,0		; Set head to 0 for now
	LD	HL,(HSTDPB)	; Get DPB pointer
	DEC	HL
	LD	B,(HL)		; Get # tracks per side
	DEC	HL		; Point to physical SPT
	LD	A,(HL)
	LD	(FDPSPT),A	; Save for FDC
	DEC	HL
	LD	A,(HL)
	LD	(FDSOFF),A	; Save sector offset
	LD	(FDS1OF),A	; For side 1 also
	DEC	HL
	DEC	HL		; Point to format byte 1
	BIT	7,(HL)
	CALL	SETTFZ		; Get high speed flag
	LD	(FDSPD),A	; Set speed for FDC
	LD	A,00000111B	; Mask for Sector Size
	AND	(HL)
	LD	(FDSECS),A	; Set Sector Size for FDC
	DEC	HL		; Point to Format Byte 0
	BIT	7,(HL)		; Test for Single-Density format
	CALL	SETTFZ
	LD	(FDSDEN),A	; Save Single-Density flag
	LD	A,(HSTTRK)	; Max track is 160
	AND	A		; Set flags if Track 0
	LD	E,A		; Put in E
	JR	NZ,FSETH1	; If not Track 0 (always side 0)
	BIT	6,(HL)
	JR	Z,FSETH1	; Test for Track 0 Single-Density
	LD	A,0FFH
	LD	(FDSDEN),A	; Set to Single-Density if Trk 0 is SD
	INC	A
	LD	(FDSECS),A	; And force 128 byte sectors
FSETH1:	LD	A,(HSTSEC)
	LD	D,A		; So stick sector in D
	LD	A,00111000B	; Mask for Double-Side mode
	AND	(HL)
	JR	Z,SETHTS	; Skip if 1-sided
	CP	00100000B	; Select Side-by-Sector?
	JR	C,SBYSEC	; ..jump if Yes
	CP	00110000B	; Select by Track LSB?
	JR	Z,SBYTLS	; ..jump if Yes
	CP	00101000B	; Select Side by Track MSB. Is Side 2 Reversed?
	JR	Z,REVTS2	; ..jump if Yes
	SUB	00010000B	; Select Side by Sector, Cont, Hd always 0?
	LD	(TSBSCF),A	;   0 if So  (Save as flag in FDC-xx)
	LD	A,E		; Get Track
	SUB	B		; Is it Side 0?
	JR	C,SETHTS	; ..jump if Side 0
UPTRK:	LD	E,A		; Else update Track
UPTRK1:	DEC	C		; Set Head 1
	JR	SETHTS		; ..and exit

REVTS2:	LD	A,E		; Get Track
	SUB	B		; Is it Side 0?
	JR	C,SETHTS	; ..jump if so
;; - Change from 2's complement to 1's complement per Ken Owen (Chameleon)
;;	NEG			; Make Track negative
	CPL			; Make Track Negative (1's complement)
	ADD	A,B		;  Add to Tracks/Side to flip
	JR	UPTRK		;   Update Head and Track, exit

SBYTLS:	SRL	E		; Divide Track by 2, Carry is Head
	JR	NC,SETHTS	; ..jump if Head 0
	JR	UPTRK1		; Else set to Head 1 and exit

SBYSEC:	SUB	00010000B	; Test for Cont Sctr Numbers
	CALL	SETTFZ		; A=0 if Continuous, FF if Same
	LD	B,A		;   save same Sect # front and back flag
	INC	HL
	INC	HL
	INC	HL
	INC	HL		; Point to physical SPT
	SRL	E		; Divide Track by 2 w/LSB going to Carry
	JR	NC,SETHTS	; ..jump if Head 0 (Even tracks)
	DEC	C		; Indicate Head 1
	INC	B		; Test if Sector # Ok
	JR	Z,SETHTS	; ..jump if Sector Numbers same on both sides
				; Else Side 1 continues from Side 0 Sctr #s
	LD	A,(FDSOFF)	; Get starting Sector for Side 0
	ADD	A,(HL)		;  Add number of sectors on Side 0
	LD	(FDS1OF),A	;   save as first Sector on Side 1

; Track (E), Side(Head in C), and Sector(D) are now sorted out, Command the FDC

SETHTS:	LD	HL,(HSTDPH)
	DEC	HL		; Point to Unit ID for drive
	LD	A,4
	AND	C		; Mask head
	OR	(HL)		; Or with unit number
	CALL	STHDRV		; Set Head and Drive (and HDR variable)
	DEC	HL
	DEC	HL		; Point to Drive Type Byte
	LD	A,DBLSTP
	AND	(HL)		; Set NZ if Double-Step Enabled
	LD	(STEP2),A	;   save in FDC module
	LD	A,E		; Get Track #
	LD	(TTRK),A	;   save in FDC module
	LD	A,(FDS1OF)	; Get sector offset
	LD	B,A		; Save for later
	  IF  CALCSK
	ADD	A,D		; Offset the Sector
	  ELSE
	LD	A,D		; Get Sector - already offset
	  ENDIF
	PUSH	AF		; Save Desired Sector # for more work
	LD	A,(FDPSPT)	; Get Sectors/Track (SPT)
	DEC	B		; Adjust SPT to Base 0
	ADD	A,B		; .add sector Offset
	LD	E,A		; Save Last Sector number
	LD	A,(FDSECS)	; Get Sector Size
	LD	D,A
	POP	AF		;   restore desired Sector #
	CALL	STSECT		; Set all Sector data
	LD	A,00000111B
	AND	(HL)		; Mask for Drive size
	LD	E,A
	BIT	5,(HL)		; Test for motor required
	CALL	SETTFZ
	LD	D,A		; Save motor flag
	LD	A,(FDSPD)
	CALL	STSIZE		; Let FDC know Speed, Size, and Motor
	LD	A,(FDSDEN)	; Get SD/DD Mode
	CALL	STMODE		;   set in FDC module
			;..fall thru to following and return to caller
; Gather parameters for this physical drive and set FDC module accordingly

DOSPEC:	LD	A,(HDR)		; Get drive in lower 3 bits
	PUSH	DE		;  save regs needed elsewhere
	CALL	SPCIFY		;   and load registers for Specify command
	CALL	SPEC		; Set Step, Head Load and Unload times
	POP	DE
	RET

;.....
; Get drive parameters for Specify Command.
; Enter: Drive in bits 0,1
; Exit : A = Step rate & Disk Size (B7=1 for 8", 0 for 5")
;	 D = Head Unload Time
;	 E = Head Load Time

SPCIFY:	CALL	PHYSCL		; Get the physical Block for this drive
	LD	A,(HL)		; Get drive byte
	AND	0111B		;  mask for Drive size
	DEC	A		;   set Zero flag if 8"
	INC	HL		; Advance to Step Rate
	LD	A,(HL)		;  fetch
	RES	7,A		;   insure MSB clear for 5/3"
	JR	NZ,SPCIF0	; Jump if Not 8"
	SET	7,A		;   else set MSB of Step for 8"
SPCIF0:	INC	HL
	LD	E,(HL)		;  get HLT
	INC	HL
	LD	D,(HL)		;   and HUT
	RET

;.....
; Index to proper Floppy Configuration bytes.  Uses AF,HL.
; Enter with Physical Drive # in Bits 0,1

	CSEG			; Must be in Common Memory

PHYSCL:	AND	0011B		; Mask out all but drive bits
	LD	L,A		;   save copy for *5 calc
	ADD	A,A		; Calc table index *2
	ADD	A,A		;  *4
	ADD	A,L		;   *5
	LD	HL,FDCSPEC	; Set table base addr
			;..fall thru to..
; Routine to Add A to HL

ADDAHL:	ADD	A,L		; Add A to LSB
	LD	L,A
	RET	NC		; Exit if no H adjustment
	INC	H		; Else had Carry, so add 1 to MSB
	RET			; And exit


	  IF  BANKED AND NOT INROM
	COMMON	/B2RAM/
	  ELSE
	DSEG
	  ENDIF

FDSECS:	 DEFS	1		; FDC sector size 0=128,1=256,2=512,3=1024
FDSDEN:	 DEFS	1		; FDC single density flag
FDSPD:	 DEFS	1		; FDC high speed flag
FDPSPT:	 DEFS	1		; FDC physical Sectors/Track
FDSOFF:	 DEFS	1		; FDC first sector number offset side 0
FDS1OF:	 DEFS	1		; FDC first sector number offset side 1
sbscflg: DEFS	1		; Flag for SBSC operation

;=========================== End of FLOPPY ================================