; Project name	:	XTIDE Universal BIOS
; Description	:	IDE Device transfer functions.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

; Structure containing variables for PIO transfer functions.
; This struct must not be larger than IDEPACK without INTPACK.
struc PIOVARS	; Must not be larger than 9 bytes! See IDEPACK in RamVars.inc.
	.wDataPort				resb	2	; 0-1, IDE Data Port
	.fnXfer					resb	2	; 2-3, Offset to transfer function
	.wSectorsInBlock		resb	2	; 4-5, Block size in sectors
	.bSectorsLeft			resb	1	; 6, Sectors left to transfer
							resb	1	; 7, IDEPACK.bDeviceControl
	.bSectorsDone			resb	1	; 8, Number of sectors xferred
endstruc


; Section containing code
SECTION .text

;--------------------------------------------------------------------
; IdeTransfer_StartWithCommandInAL
;	Parameters:
;		AL:		IDE command that was used to start the transfer
;				(all PIO read and write commands including Identify Device)
;		ES:SI:	Ptr to normalized data buffer
;		DS:DI:	Ptr to DPT (in RAMVARS segment)
;		SS:BP:	Ptr to IDEPACK
;	Returns:
;		AH:		INT 13h Error Code
;		CX:		Number of successfully transferred sectors
;		CF:		Cleared if success, Set if error
;	Corrupts registers:
;		AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
IdeTransfer_StartWithCommandInAL:
	; Are we reading or writing?
	test	al, 16	; Bit 4 is cleared on all the read commands but set on 3 of the 4 write commands
	mov		ah, [bp+IDEPACK.bSectorCount]
	jnz		SHORT WriteToDrive
	cmp		al, COMMAND_WRITE_MULTIPLE
	je		SHORT WriteToDrive
	; Fall to ReadFromDrive

;--------------------------------------------------------------------
; ReadFromDrive
;	Parameters:
;		AH:		Number of sectors to transfer (1...128)
;		ES:SI:	Normalized ptr to buffer to receive data
;		DS:DI:	Ptr to DPT (in RAMVARS segment)
;		SS:BP:	Ptr to PIOVARS
;	Returns:
;		DS:DI:	Ptr to DPT (in RAMVARS segment)
;		AH:		BIOS Error code
;		CX:		Number of successfully transferred sectors
;		CF:		0 if transfer successful
;				1 if any error
;	Corrupts registers:
;		AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ReadFromDrive:
	; Prepare to read data to ESSI
	mov		bx, g_rgfnPioRead
	call	InitializePiovarsInSSBPwithSectorCountInAH

	; Wait until drive is ready to transfer
	call	IdeWait_IRQorDRQ					; Wait until ready to transfer
	jc		SHORT ReturnWithTransferErrorInAH
	xchg	si, di								; ES:DI now points buffer

	mov		cx, [bp+PIOVARS.wSectorsInBlock]	; Max 128

ALIGN JUMP_ALIGN
.ReadNextBlockFromDrive:
	mov		dx, [bp+PIOVARS.wDataPort]
	cmp		[bp+PIOVARS.bSectorsLeft], cl
	jbe		SHORT .ReadLastBlockFromDrive
	call	[bp+PIOVARS.fnXfer]

	; Wait until ready for next block and check for errors
	xchg	di, si								; DS:DI now points DPT
	call	IdeWait_IRQorDRQ					; Wait until ready to transfer
	jc		SHORT ReturnWithTransferErrorInAH
	xchg	si, di								; ES:DI now points buffer

	; Increment number of successfully read sectors
	mov		cx, [bp+PIOVARS.wSectorsInBlock]
	sub		[bp+PIOVARS.bSectorsLeft], cl
	add		[bp+PIOVARS.bSectorsDone], cl
	jmp		SHORT .ReadNextBlockFromDrive

ALIGN JUMP_ALIGN
.ReadLastBlockFromDrive:
	mov		cl, [bp+PIOVARS.bSectorsLeft]		; CH is already zero
	push	cx
	call	[bp+PIOVARS.fnXfer]					; Transfer possibly partial block

	; Check for errors in last block
	mov		di, si								; DS:DI now points DPT
CheckErrorsAfterTransferringLastBlock:
	mov		bx, TIMEOUT_AND_STATUS_TO_WAIT(TIMEOUT_DRQ, FLG_STATUS_BSY)
	call	IdeWait_PollStatusFlagInBLwithTimeoutInBH
	pop		cx	; [bp+PIOVARS.bSectorsLeft]
	jc		SHORT ReturnWithTransferErrorInAH

	; All sectors successfully transferred
	add		cx, [bp+PIOVARS.bSectorsDone]		; Never sets CF
	ret

	; Return number of successfully read sectors
ReturnWithTransferErrorInAH:
%ifdef USE_386
	movzx	cx, [bp+PIOVARS.bSectorsDone]
%else
	mov		cl, [bp+PIOVARS.bSectorsDone]
	mov		ch, 0								; Preserve CF
%endif
	ret


;--------------------------------------------------------------------
; WriteToDrive
;	Parameters:
;		AH:		Number of sectors to transfer (1...128)
;		DS:DI:	Ptr to DPT (in RAMVARS segment)
;		ES:SI:	Normalized ptr to buffer containing data
;		SS:BP:	Ptr to PIOVARS
;	Returns:
;		AH:		BIOS Error code
;		CX:		Number of successfully transferred sectors
;		CF:		0 if transfer successful
;				1 if any error
;	Corrupts registers:
;		AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
WriteToDrive:
	; Prepare to write data from ESSI
	mov		bx, g_rgfnPioWrite
	call	InitializePiovarsInSSBPwithSectorCountInAH

	; Always poll when writing first block (IRQs are generated for following blocks)
	mov		bx, TIMEOUT_AND_STATUS_TO_WAIT(TIMEOUT_DRQ, FLG_STATUS_DRQ)
	call	IdeWait_PollStatusFlagInBLwithTimeoutInBH
	jc		SHORT ReturnWithTransferErrorInAH

	mov		cx, [bp+PIOVARS.wSectorsInBlock]	; Max 128

ALIGN JUMP_ALIGN
.WriteNextBlockToDrive:
	mov		dx, [bp+PIOVARS.wDataPort]
	cmp		[bp+PIOVARS.bSectorsLeft], cl
	jbe		SHORT .WriteLastBlockToDrive
	call	[bp+PIOVARS.fnXfer]

	; Wait until ready for next block and check for errors
	call	IdeWait_IRQorDRQ					; Wait until ready to transfer
	jc		SHORT ReturnWithTransferErrorInAH

	; Increment number of successfully written sectors
	mov		cx, [bp+PIOVARS.wSectorsInBlock]
	sub		[bp+PIOVARS.bSectorsLeft], cl
	add		[bp+PIOVARS.bSectorsDone], cl
	jmp		SHORT .WriteNextBlockToDrive

ALIGN JUMP_ALIGN
.WriteLastBlockToDrive:
	mov		cl, [bp+PIOVARS.bSectorsLeft]		; CH is already zero
	push	cx
%ifdef USE_186
	push	CheckErrorsAfterTransferringLastBlock
	jmp		[bp+PIOVARS.fnXfer]					; Transfer possibly partial block
%else
	call	[bp+PIOVARS.fnXfer]					; Transfer possibly partial block
	jmp		SHORT CheckErrorsAfterTransferringLastBlock
%endif


;--------------------------------------------------------------------
; InitializePiovarsInSSBPwithSectorCountInAH
;	Parameters:
;		AH:		Number of sectors to transfer (1...128)
;		BX:		Offset to transfer function lookup table
;		DS:DI:	Ptr to DPT (in RAMVARS segment)
;		SS:BP:	Ptr to PIOVARS
;	Returns:
;		Nothing
;	Corrupts registers:
;		AX, BX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
InitializePiovarsInSSBPwithSectorCountInAH:
	; Store sizes and Data Port
	mov		[bp+PIOVARS.bSectorsLeft], ah
	mov		ax, [di+DPT.wBasePort]
	mov		[bp+PIOVARS.wDataPort], ax
	eMOVZX	ax, [di+DPT_ATA.bBlockSize]
	mov		[bp+PIOVARS.wSectorsInBlock], ax
	mov		[bp+PIOVARS.bSectorsDone], ah		; Zero

	; Get transfer function based on bus type
	xchg	ax, bx								; Lookup table offset to AX
	mov		bl, [di+DPT_ATA.bDevice]
	add		bx, ax
	mov		ax, [cs:bx]							; Load offset to transfer function
	mov		[bp+PIOVARS.fnXfer], ax
	ret



; Lookup tables to get transfer function based on bus type
ALIGN WORD_ALIGN
g_rgfnPioRead:
%ifdef USE_AT
		dw		IdePioBlock_ReadFrom16bitDataPort	; 0, DEVICE_16BIT_ATA
		dw		IdePioBlock_ReadFrom32bitDataPort	; 1, DEVICE_32BIT_ATA
%else
		dd		0
%endif
%ifdef MODULE_8BIT_IDE
		dw		IdePioBlock_ReadFromXtideRev1		; 2, DEVICE_8BIT_XTIDE_REV1
	%ifndef USE_AT
		g_rgfnPioWrite:
	%endif
		dw		IdePioBlock_ReadFromXtideRev2		; 3, DEVICE_8BIT_XTIDE_REV2
		dw		IdePioBlock_ReadFrom8bitDataPort	; 4, DEVICE_8BIT_XTCF_PIO8
%endif

%ifdef USE_AT
g_rgfnPioWrite:
		dw		IdePioBlock_WriteTo16bitDataPort	; 0, DEVICE_16BIT_ATA
		dw		IdePioBlock_WriteTo32bitDataPort	; 1, DEVICE_32BIT_ATA
%endif
%ifdef MODULE_8BIT_IDE
		dw		IdePioBlock_WriteToXtideRev1		; 2, DEVICE_8BIT_XTIDE_REV1
		dw		IdePioBlock_WriteToXtideRev2		; 3, DEVICE_8BIT_XTIDE_REV2
		dw		IdePioBlock_WriteTo8bitDataPort		; 4, DEVICE_8BIT_XTCF_PIO8
%endif