; Project name	:	Assembly Library
; Description	:	Functions for size calculations.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 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
;

%ifdef INCLUDE_MENU_LIBRARY
struc BYTE_MULTIPLES
	.B			resb	1
	.kiB		resb	1
	.MiB		resb	1
	.GiB		resb	1
	.TiB		resb	1
endstruc

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Size_GetSizeToAXAndCharToDLfromBXDXAXwithMagnitudeInCX
;	Parameters:
;		BX:DX:AX:	Size in magnitude
;		CX:			Magnitude in BYTE_MULTIPLES
;	Returns:
;		AX:			Size in magnitude
;		CX:			Tenths
;		DL:			Magnitude character:
;						'k' = *1024   B = kiB
;						'M' = *1024 kiB = MiB
;						'G' = *1024 MiB = GiB
;						'T' = *1024 GiB = TiB
;						'P' = *1024 TiB = PiB
;	Corrupts registers:
;		BX, DH
;--------------------------------------------------------------------
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_GetSizeToAXAndCharToDLfromBXDXAXwithMagnitudeInCX:
%ifndef USE_186		; If 8086/8088
	push	di
%endif
	push	si

ALIGN UTIL_SIZE_JUMP_ALIGN
.MagnitudeConversionLoop:
	ePUSH_T	di, .MagnitudeConversionLoop; DI corrupted only on 8086/8088 build
%ifdef USE_186
	test	bx, bx						; Bits 32...47 in use?
	jnz		SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
	test	dx, dx						; Bits 16...31 in use?
	jnz		SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
%else ; 808x
	mov		di, bx
	or		di, dx
	jnz		SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
%endif
	cmp		ax, 10000					; 5 digits needed?
	jae		SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
	add		sp, BYTE 2					; Clean return address from stack

	; Convert remainder to tenths
	mov		bx, 640
	xchg	bx, ax						; BX = Size, AX = (10 / 1024) * 65536
	mul		si							; DX = Remainder * (10 / 1024)
	xchg	dx, ax
	xchg	cx, ax						; CX = Tenths, AX = Magnitude
	xchg	bx, ax						; AX = Size, BX	= Magnitude

	; Convert magnitude to character
	mov		dl, [cs:bx+.rgbMagnitudeToChar]

	pop		si
%ifndef USE_186
	pop		di
%endif
	ret
.rgbMagnitudeToChar:	db	" kMGTP"

;--------------------------------------------------------------------
; Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
;	Parameters:
;		BX:DX:AX:	Size
;		CX:			Magnitude in BYTE_MULTIPLES (must be 254 or less)
;	Returns:
;		BX:DX:AX:	Size in magnitude
;		SI:			Remainder (0...1023)
;		CX:			Magnitude in BYTE_MULTIPLES
;	Corrupts registers:
;		Nothing
;--------------------------------------------------------------------
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX:
	inc		cx						; Increment magnitude
	mov		si, 1023
	and		si, ax					; Remainder now in SI
	; Fall to Size_DivideSizeInBXDXAXby1024
%endif ; INCLUDE_MENU_LIBRARY

;--------------------------------------------------------------------
; Size_DivideSizeInBXDXAXby1024
;	Parameters:
;		BX:DX:AX:	Size
;		CX:			Must be 255 or less
;	Returns:
;		BX:DX:AX:	Size divided by 1024
;	Corrupts registers:
;		Nothing
;--------------------------------------------------------------------
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_DivideSizeInBXDXAXby1024:
%ifdef USE_386
	shrd	ax, dx, 10
	shrd	dx, bx, 10
	shr		bx, 10
%else
	push	cx
	mov		cl, 10
ALIGN UTIL_SIZE_JUMP_ALIGN
.ShiftLoop:
	call	Size_DivideBXDXAXbyTwo
	loop	.ShiftLoop
	pop		cx
%endif
	ret

;--------------------------------------------------------------------
; Size_ConvertSectorCountInBXDXAXtoKiB
; Size_DivideBXDXAXbyTwo
;	Parameters:
;		BX:DX:AX:	Total sector count
;	Returns:
;		BX:DX:AX:	Total size in kiB
;		CF:			Remainder from division
;	Corrupts registers:
;		Nothing
;--------------------------------------------------------------------
%ifdef EXCLUDE_FROM_XUB
	%ifdef USE_386
		%define EXCLUDE
	%endif
	%ifdef MODULE_BOOT_MENU
		%undef EXCLUDE
	%endif
%endif

%ifndef EXCLUDE
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_ConvertSectorCountInBXDXAXtoKiB:	; unused entrypoint ok
Size_DivideBXDXAXbyTwo:					; unused entrypoint ok
	shr		bx, 1					; Divide sector count by 2...
	rcr		dx, 1					; ...to get disk size in...
	rcr		ax, 1					; ...kiB
	ret
%endif
%undef EXCLUDE