;CONVERT A BCPL STRING.
;CALL WITH CVRT(STRING POINTER,Xcoordinate,
;LWA-NWRDS,FONT,MAXWIDTH,MAXHEIGHT,NWRDS)
;RETURNS THE WIDTH OF THE STRING IN BITS, AND STORES ITS MAX
;HEIGHT IN MaxStringHeight

;OFFSETS IN THE FRAME
STRINGPOINTER=4
Xstart=5
Ystart=6
LWA=7
FontPointer=10
Face = 11	;Bit0-13 = position hardcopy, Bit 14 = make Bold,  bit 15 = make Italics
WidthPointer = 12
MagFlag = 13
fNwrds = 14
DBA = 15
Xposn=16
MicaPosn=17
currXposn=20
Char=21
CharPointer=22
height=23
MaxHeight=24
BoldFlg=25
OverHang=26
CHARSDONE=27
RET=30

.BEXTZ MaxStringHeight, HardCopy, ItalicsBuff, Mag, WindowYmin, WindowXmin
.BEXTZ DisplayArea, SetBPtr, OnBits, OffBits, SetBMask, MaskTable
.ENT Cvrt
.SREL

Cvrt:	CSTRT
	.NREL
CSTRT:	STA 3 1 2
	JSR@ 370
	40
	JSR@ 367
	LDA 0 @STRINGPOINTER,2
	LDA 1 C177400
	ANDS 1 0 SNR
	JMP@ 366
	STA 0 CHARSDONE,2
	lda 1 Xstart,2
	sta 1 Xposn,2;			Xposn is updated to mica precision	

	lda 0 ScreenYmax
	lda 1 Ystart,2
	SUB 1 0
	sta 0 MaxHeight,2;		save ScreenYmax-Yposn in MaxHeight	

	SUB 0 0
	STA 0  MaxStringHeight
	STA 0  MicaPosn,2
	STA 0  OverHang,2;  	set height to zero for non-italics strings
	sta 2 SavedAC2

DoRight:	LDA 1 @STRINGPOINTER,2
	JSR StartCvrt
	ISZ STRINGPOINTER,2
	DSZ CHARSDONE,2
	JMP DoLeft
	JMP DoExit

DoLeft:	LDA 1 @STRINGPOINTER,2
	MOVS 1 1
	JSR StartCvrt
	DSZ CHARSDONE,2
	JMP DoRight

;return string length is screen bits
;AC0 _ (Xposn-Xstart) + Overhang/4 + BoldFace? 1,0
DoExit:	lda 0 Xposn,2
	lda 1 Xstart,2
	sub 1 0
	lda 3 Face,2;			BoldFace bit is C14
	lda 1 OverHang,2	
	movzr 1 1;			divide OverHang by 2
	add 3 1;				add 2 to width calculation if boldface
	movzr 1 1;			divide (OverHang + boldface) by 2 to set true overhang
	add 1 0
	JMP@ 366

StartCvrt:	STA 3 RET,2
	LDA 3 C177;			Mask the character code in AC1
	AND 3 1
	lda 0 HardCopy;		check for hardcopy mode
	mov 0 0 SNR
	jmp DoCvrt

;MicaPosn = MicaPosn + WidthPointer!char
;Xposn = Xstart + MicaPosn*1778/50
SetBitPsn:	STA 1 Char,2;			save Char since I need the AC
	lda 3 WidthPointer,2
	ADD 1 3
	lda 0 0,3;				get with from WidthPointer!char
	lda 1 MicaPosn,2
	ADD 1 0
	sta 0 MicaPosn,2;		MicaPosn is updated to the new coordinate	
	lda 2 C50;			Now scale MicaPosn to required Alto Xposn value
	lda 0 C1778
	MOVZR 0 0  
	MUL
	LDA 2 C1778
	DIV
	MOV# 0,0;			noop return for negative result
	lda 2 SavedAC2; 		***AC2 restored
	lda 0 Xstart,2;  
	add 0 1
	sta 1 Xposn,2;  		jam mica computed value into Xposn
	lda 1 Char,2


DoCvrt:	lda 0 Face,2;			First check if Italics conversion is required and save BoldFlag
	movzr 0 0 SZC;		Skip on carry generated 2 instructions back
	jmp DoItalics;			ifso go make a "sliced" copy of the character definition
	sta 0 BoldFlg,2;		save original bit 14 as the Bold Flag bit

ContCvrt:	LDA 3 FontPointer,2;	assumes AC1 has character code in it
	ADD 1 3
	STA 3 CharPointer,2;	Save pointer to character pointer in font vor Convert
	LDA 0 0 3
	ADD 0 3;				NOW POINTS TO 2*WIDTH+1 OR PSEUDOCHAR
	STA 3 CharDef;		Save pointer to character entry in font
	LDA 0 0 3;			2*WIDTH OR PSEUDO
	MOVZR 0 0 SNC
	LDA 0 C20;			PSEUDO-CHAR. THIS PART'S WIDTH IS 16
	LDA 1 Xposn,2
	ADD 1 0
	STA 0 Xposn,2;		UPDATE WIDTH  Save Xposn for current char in AC1


	LDA 0 1 3;			XH,HD FOR THIS CHARACTER
	MOVS 0 3
	ADD 3 0
	LDA 3 C377
	AND 3 0;				TOTAL HEIGHT BELOW ORIGIN
	LDA 3 MaxStringHeight;  MAX HEIGHT SO FAR
	SGT 3 0
	STA 0 MaxStringHeight;  CURRENT IS BIGGER
	LDA 3 MaxHeight,2	;MAXIMUM ALLOWED HEIGHT
	SGT 3 0
	JMP MagCvrt;			MagCvrt will clip at the screen boundaries
	LDA 3 ScreenXmax;	See if part of the character lies to the right of the screen
	LDA 0 Xposn,2
	SGT 3 0
	JMP MagCvrt;			MagCvrt will clip at the screen boundaries

	LDA 3 MagFlag,2;		See if we need to do a Magnified Convert
	MOVZR 3 3 SZR
	JMP MagCvrt


	MOVZR 1 0;			Now set up the required parameters ofe Convert
	MOVZR 0 0
	MOVZR 0 0
	MOVZR 0 0
	LDA 3 LWA,2
	ADD 3 0;				WAD in AC0 for CONVERT
	LDA 3 C17;			compute Xposn into DWA and DBA
	AND 3 1
	SUB 1 3;				DBA _ 15 - (BitPosn & #17)

RpCONV:	STA 3 DBA,2
	LDA 3 CharPointer,2
	CONVERT fNwrds
	JMP DoExtn;			CHARACTER HAS AN EXTENSION
DnCVRT:	lda 3 BoldFlg,2
	movzr 3 3 SNC
	JMP@ RET,2
MkBold:	sta 3 BoldFlg,2;		Bold characters are done by calling Convert again 1 bit to the right 
	adc 3 3
	addz 1 3 SZC
	jmp RpCONV
	inc 0 0
	lda 1 C20
	add 1 3
	jmp RpCONV

ScreenXmax:	576.;				**As defined in Sil.defs  (Nwrds*16)
ScreenYmax:	762.;				**As defined in Sil.defs	
DsiplaySize:	27432.;				**As defined by Sil.defs  (Nwrds*ScreenYmax)
C177400:	177400
C377:	377
C237:	237
C177:	177
C20:	20
C17:	17
C50:	50.;					This value must match SilPress.bcpl for screen to mica conversion
C1778:	1778.;				This value must match SilPress.bcpl for screen to mica conversion
SavedAC2:	0
CharDef:	0

	
;copy the entire character definition from the font to the ItalicsBuff 
DoItalics:	sta 0 BoldFlg,2;		save original bit 14 as the Bold Flag bit
	LDA 3 FontPointer,2;	assumes AC1 has character code in it
	ADD 1 3
	LDA 0 0 3
	ADD 0 3;				NOW POINTS TO 2*WIDTH+1 OR PSEUDOCHAR
	LDA 0 1,3;			get the height
	LDA 1 C377
	AND 0 1;				mask to just the height and check for zero height
	sta 1 height,2
	sta 1 OverHang,2;		save max shift in OverHang
	inc 1 1;				AC1 now has height+1
	sub 1 3
	mov 3 0
	com 1 3;				AC3 now has -(height+2)
	lda 1 ItalicsBuff
	inc 1 1;				AC1 now points to ItalicsBuff+1
	BLT
	lda 1 height,2
	lda 3 ItalicsBuff
	sub 1 3
	sta 3 Char,2

;let height = XH
;[
;ItalicsBuff!height = ItalicsBuff!height rshift (height/4)
;height = height-1
;if height ls 4 then break
;] repeat
ItalicsL:	movzr 1 1
	movzr 1 1 SNR;		divide ht by 4
	jmp exitItalics
	lda 0 @Char,2
	jsr @347;			rshift  AC0 AC1 times
	sta 0 @Char,2
	isz Char,2
	dsz height,2
	lda 1 height,2;			set AC0 to -1
	jmp ItalicsL

exitItalics:	lda 1 C237;			put Dummmy char pointer into AC1
	jmp ContCvrt

DoExtn: 	sta 3 CharDef;			save extended char in CharDef (CharDef is not used now)
	lda 3 BoldFlg,2
	movzr 3 3 SZC
	JMP MkBold
	lda 1 CharDef
	jmp DoCvrt



; * * * * * * * * * * * * * * * * * * * 
;The rest of the code implements a Magnified version of the Convert process

;Exit from MagCvrt  --  put here for address range placement
MagDn:	lda 2 SavedAC2
	lda 1 @CharDef
	movzr 1 1 szc
	jmp@ RET,2
	jmp DoCvrt

MagCvrt:	sta 1 currXposn,2

;let XH = -(CharDef!1 & #377)  //number of scanlines to Convert
	lda 3 CharDef
	lda 3 1,3;	CharDef!1
	lda 1 C377;			CharDef!1 is stIll in AC3
	and 3 1
	sub 0 0
	sub 1 0 SNR;			Nothing to do on zero height (space) characters
	jmp MagDn
	sta 0 XH

;let HD = CharDef!1 rshift 8  //number of scanlines to skip
;let y = (Ystart+HD-WindowYmin)*Mag  //not really saved
;SetBPtr = DisplayArea + (y*Nwrds)
	lda 0 C177400;		CharDef!1 is stall in AC3
	ands 3 0;				HD IN AC0
	lda 1 Ystart,2
	add 1 0
	lda 1 WindowYmin
	sub 1 0
	lda 1 Mag
	jsr @343;			Multiply
	lda 0 Nwrds;			y is now in AC1
	jsr @343;			Multiply
	lda 0 DisplayArea
	add 0 1
	sta 1 SetBPtr

;Yinc = Nwrds*Mag
	lda 1 Mag
	lda 0 Nwrds
	jsr @343;			Multiply
	sta 1 Yinc

;Ymax = DisplayArea + DsiplaySize-Yinc
	lda 0 DsiplaySize;		Yinc is in AC1
	sub 1 0
	lda 1 DisplayArea
	add 1 0
	sta 0 Ymax

;OnBits = MaskTable!( Mag+ (BoldFlg? Mag/2, 0) )
	lda 0 Mag
	movzr 0 1
	lda 3 BoldFlg,2
	mov 3 3 szr
	add 1 0
	lda 3 MaskTable
	add 0 3
	lda 0 0,3
	com 0 0
	sta 0 OnBits

;let Xpos= (currXposn-WindowXmin)*Mag
	lda 0 currXposn,2
	lda 1 WindowXmin
	sub 1 0
	lda 1 Mag
	jsr @343; Mul
	lda 3 C17
	com 3 0;				put the constant C177760 in AC0

	and 1 0
	movl# 0 0 SZC
	add 3 0
	cycle 14
	sta 0 Xpos
; OnBits,,OffBits = (OnBits,,OffBits) rshift (Xposn&#17)
	and 1 3
	sub 2 2
	sub 3 2;				leave (-xposn&#17) in AC2
	lda 0 OnBits
	adc 1 1
	jsr MaskSh
	sta 0 OnBits
	sta 1 OffBits
	jmp Yloop

Nwrds:	36.;					**As defined in Sil.defs
Yinc:	0
Ymax:	0
Xpos:	0
Xptr:	0
XH:	0
Cnt:	0
wd1:	0

;now set up outside loop
;for sl = -XH to -1 do
Yloop:	lda 2 SetBPtr;			check for y to small: ifso skip to next scan line
	lda 3 DisplayArea
	subo# 3 2 SZC
	jmp Ydn
	lda 3 Ymax;			check for y to big: ifso done with conversion
	SGT 3 2
	jmp MagDn
	lda 0 Xpos
	sta 0 Xptr
	lda 0 OnBits
	lda 1 OffBits
	sta 1 wd1
	lda 1 CharDef
	lda 3 XH
	add 1 3
	lda 1 0,3;				lda AC1 with Bits from CharDef!-XH
	lda 2 Mag
	jmp NxtBit

;now the end of the loop
Ydn:	lda 2 Yinc
	lda 3 SetBPtr
	add 2 3
	sta 3 SetBPtr
	isz XH;				test for all scan lines converted
	jmp Yloop
	jmp MagDn

;Now drop into the main bit per scanline loop
;[  //find the next "on"bit in the font and shift the mask bits accordingly
;ShiftCnt = ShiftCnt-Mag
;if FontBits = 0 then break
;let GotBit = (FontBits&#100000) ne 0
;FontBits = FontBits lshift 1
;unless GotBit then loop
;] repeat
;MaskSh(onBits,OffBits,ShiftCnt)
NxtBit:	lda 3 Mag
NxtBitL:	sub 3 2;				assumes initial shift cnt in AC3, inc
	mov 1,1 SNR;			expects Bits to be in AC1
	jmp Ydn
	movzl 1,1 SNC
	jmp NxtBitL
	sta 1 SetBMask
	lda 1 wd1; 			restore AC1 with word 1
	jsr MaskSh

Bounds:	lda 3 Xptr
	movl# 3 3 SZC;		skip is Xptr is ls 0
	jmp BitDn
	lda 2 Nwrds;			return is Xptr gr Nwrds
	subz 3,2 SBN
	jmp Ydn
	com# 1 1 SNR;		skip if (word 1 ne 0) & (Xptr eq Nwrds)
	jmp SetBit
	movzr 2 2 SNR
	jmp Ydn

SetBit:	lda 3 Mag;			find the first memory word address to be modified
	sta 3 Cnt
	lda 3 SetBPtr
	lda 2 Xptr
	add 2,3
SetBitL:	lda 2 0,3;				get word from screen
	and 0 2
	adc 0 2;				result in AC2 and AC0 is left complemented
	sta 2 0,3
	com# 1 1 SNR;		skip if wd1 is all zero
	jmp xitL0
	lda 2 1,3;				get word from screen
	and 1 2
	adc 1 2;				result in AC2 and AC1 is left complemented
	sta 2 1,3
xitL0:	lda 2 Nwrds
	add 2 3;				increment mem pointer by one scan line
	dsz Cnt
	jmp SetBitL
BitDn: 	sub 2 2
	sta 1 wd1	
	lda 1 SetBMask
	jmp NxtBit

;right shift the 32 bit quantity "OnBits,OffBits"
;if OnBits is all zero, then swap words and increment Xptr
;NOTE the content of OnBits,OffBits are to be or'd into the bit map,
;and for convenience of the "OR" algorithm are complements of the bits to be or'd.
MaskSh:	sta 3 Cnt;			Cnt is a handy unused register at this point
	mov 2 2 SNR;			AC2 contains toe quantity to be shifted
	jmp@ Cnt;			skip if we don't have any count
shiftL:	movor 0,0;			now shift the bit pattern
	movr 1,1
	com 0,3 SZR;			swap words and increment Xptr if all bits are in OffBits
	jmp ShiftDn
	mov 1 0
	com 3 1
	isz Xptr
ShiftDn:	inc 2,2 SZR;			test for all bits shifted
	jmp shiftL
	jmp@ Cnt

	.end
;(0,4896)