mirror of
https://github.com/jrk/QuickDraw.git
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294 lines
9.3 KiB
Plaintext
294 lines
9.3 KiB
Plaintext
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.INCLUDE GrafTypes.text
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.FUNC AngleFromSlope,1
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.DEF SlopeFromAngle
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;-----------------------------------------------------
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;
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; FUNCTION AngleFromSlope(slope: Fixed): INTEGER;
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;
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; Scans slope table for angle and returns angle 0..180
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;
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MOVE.L 4(SP),D0 ;GET SLOPE
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SMI D2 ;REMEMBER IF IT WAS NEGATIVE
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BPL.S NOTNEG ;CONTINUE IF POSITIVE
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NEG.L D0 ;ELSE MAKE SLOPE POS
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NOTNEG SUB.L #500,D0 ;BIAS THE COMPARE
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MOVE.L D0,4(SP)
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LEA CONTINUE,A0 ;POINT TO TABLE OF SLOPES
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MOVEQ #-1,D1 ;INIT ANGLE COUNT
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SCAN ADD.W #1,D1
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MOVE.W D1,D0
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CLR.L -(SP)
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BRA.S A2SLOPE
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CONTINUE
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MOVE.L 8(SP),D0 ;GET SLOPE
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CMP.L (SP)+,D0 ;SCAN THRU SLOPE TABLE
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BGT.S SCAN
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MOVE #180,D0
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SUB D1,D0 ;CALC 180-ANGLE = 90..180
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TST.B D2 ;WAS DH POS ?
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BPL.S DONE ;NO, RETURN 90..180
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MOVE D1,D0 ;YES, RETURN 0..90
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DONE MOVE.L (SP)+,(SP) ;STRIP PARAM
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MOVE.W D0,4(SP) ;RETURN FUNCTION RESULT
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RTS
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;----------------------------------------------------------------
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;
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; FUNCTION SlopeFromAngle(angle: INTEGER): Fixed;
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;
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; calculate the fixed point slope of a line, DH/DV = -65536 * Tan(angle).
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; Input angle is treated MOD 180.
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;
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SlopeFromAngle
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MOVE.L (SP)+,A0 ;POP RETURN ADDR
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MOVE (SP)+,D0 ;GET INTEGER ANGLE
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EXT.L D0 ;SIGN EXTEND FOR DIVIDE
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DIVS #180,D0 ;TREAT ANGLE MOD 180
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SWAP D0 ;GET THE REMAINDER
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TST D0 ;WAS IT NEGATIVE ?
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BPL.S OK1 ;NO, CONTINUE
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ADD #180,D0 ;YES, PUT IN RANGE 0..179
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OK1 MOVE #$8000,(SP)
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A2SLOPE CMP #90,D0
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BLE.S OK2
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CLR.W (SP)
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SUB #180,D0
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NEG D0
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OK2 CMP #45,D0
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BLT.S SHARE
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ADD #1,(SP)
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CMP #64,D0
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BLT.S SHARE
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MOVE.B SLOPE-91(D0),1(SP)
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BPL.S SHARE
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OR.B #$7F,(SP)
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SHARE ADD D0,D0
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MOVE.W SLOPE(D0),2(SP)
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CHECK BCLR #7,(SP)
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BEQ.S OK3
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NEG.L (SP)
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OK3 JMP (A0)
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; .BYTE $01 ;45
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01 ;50
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01 ;55
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01
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; .BYTE $01 ;60
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; .BYTE $01
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; .BYTE $01
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.BYTE $01
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.BYTE $02
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.BYTE $02 ;65
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.BYTE $02
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.BYTE $02
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.BYTE $02
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.BYTE $02
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.BYTE $02 ;70
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.BYTE $02
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.BYTE $03
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.BYTE $03
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.BYTE $03
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.BYTE $03 ;75
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.BYTE $04
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.BYTE $04
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.BYTE $04
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.BYTE $05
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.BYTE $05 ;80
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.BYTE $06
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.BYTE $07
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.BYTE $08
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.BYTE $09
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.BYTE $0B ;85
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.BYTE $0E
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.BYTE $13
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.BYTE $1C
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.BYTE $39
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.BYTE $FF ;90
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SLOPE
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.WORD $0000 ;0
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.WORD $0478
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.WORD $08F1
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.WORD $0D6B
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.WORD $11E7
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.WORD $1666 ;5
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.WORD $1AE8
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.WORD $1F6F
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.WORD $23FA
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.WORD $288C
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.WORD $2D24 ;10
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.WORD $31C3
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.WORD $366A
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.WORD $3B1A
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.WORD $3FD4
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.WORD $4498 ;15
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.WORD $4968
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.WORD $4E44
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.WORD $532E
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.WORD $5826
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.WORD $5D2D ;20
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.WORD $6245
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.WORD $676E
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.WORD $6CAA
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.WORD $71FB
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.WORD $7760 ;25
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.WORD $7CDC
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.WORD $8270
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.WORD $881E
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.WORD $8DE7
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.WORD $93CD ;30
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.WORD $99D2
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.WORD $9FF7
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.WORD $A640
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.WORD $ACAD
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.WORD $B341 ;35
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.WORD $B9FF
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.WORD $C0E9
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.WORD $C802
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.WORD $CF4E
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.WORD $D6CF ;40
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.WORD $DE8A
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.WORD $E681
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.WORD $EEB9
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.WORD $F737
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.WORD $0000 ;45
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.WORD $0919
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.WORD $1287
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.WORD $1C51
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.WORD $267F
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.WORD $3117 ;50
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.WORD $3C22
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.WORD $47AA
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.WORD $53B9
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.WORD $605B
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.WORD $6D9B ;55
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.WORD $7B89
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.WORD $8A35
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.WORD $99AF
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.WORD $AA0E
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.WORD $BB68 ;60
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.WORD $CDD6
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.WORD $E177
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.WORD $F66E
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.WORD $0CE1
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.WORD $24FE ;65
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.WORD $3EFC
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.WORD $5B19
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.WORD $799F
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.WORD $9AE7
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.WORD $BF5B ;70
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.WORD $E77A
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.WORD $13E3
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.WORD $4556
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.WORD $7CC7
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.WORD $BB68 ;75
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.WORD $02C2
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.WORD $54DB
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.WORD $B462
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.WORD $2501
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.WORD $ABD9 ;80
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.WORD $5051
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.WORD $1D88
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.WORD $24F3
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.WORD $83AD
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.WORD $6E17 ;85
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.WORD $4CF5
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.WORD $14BD
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.WORD $A2D7
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.WORD $4A30
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.WORD $FFFF ;90
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.PROC PtToAngle,3
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.REF AngleFromSlope
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;--------------------------------------------------------------
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;
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; PROCEDURE PtToAngle(r: Rect; pt: Point; VAR angle: INTEGER);
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;
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; Given a rectangle and a point, return the angle subtended by pt.
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;
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; A6 OFFSETS OF PARAMETERS AFTER LINK:
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;
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PARAMSIZE .EQU 12 ;TOTAL BYTES OF PARAMS
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RECT .EQU PARAMSIZE+8-4 ;ADDR OF RECT
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PT .EQU RECT-4 ;POINT
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ANGLE .EQU PT-4 ;ADDR OF INTEGER;
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LINK A6,#0 ;NO LOCALS
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MOVEM.L D6-D7/A4,-(SP) ;SAVE REGS
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MOVE.L RECT(A6),A4 ;POINT TO RECT
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MOVE BOTTOM(A4),D0
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ADD TOP(A4),D0
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ASR #1,D0 ;CENTER.V := (TOP+BOTTOM)/2
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MOVE PT+V(A6),D1
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SUB D0,D1 ;DV := PT.V - CENTER.V
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MOVE RIGHT(A4),D0
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ADD LEFT(A4),D0
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ASR #1,D0 ;CENTER.H := (LEFT+RIGHT)/2
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MOVE PT+H(A6),D7
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SUB D0,D7 ;DH := PT.H - CENTER.H
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BNE.S DHOK ;CONTINUE IF DH <> 0
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TST D1 ;WAS DV > 0 ?
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BLE.S ZERO ;NO, RETURN ANGLE = 0
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MOVE #180,D0 ;YES, RETURN ANGLE = 180
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BRA.S DONE
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DHOK CLR.L -(SP) ;ROOM FOR FCN RESULT
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MOVE D7,-(SP) ;PUSH DH
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MOVE D1,-(SP) ;PUSH DV
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_FixRatio ;CALC SLOPE := DH/DV
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MOVE.L (SP)+,D6 ;GET SLOPE RESULT
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CLR.L -(SP) ;ROOM FOR FCN RESULT
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MOVE BOTTOM(A4),D0
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SUB TOP(A4),D0
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MOVE D0,-(SP) ;PUSH HEIGHT
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MOVE RIGHT(A4),D0
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SUB LEFT(A4),D0
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MOVE D0,-(SP) ;PUSH WIDTH
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_FixRatio ;CALC ASPECT := HT/WD
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MOVE.L (SP)+,D0 ;GET ASPECT RESULT
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CLR.L -(SP) ;ROOM FOR FCN RESULT
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MOVE.L D6,-(SP) ;PUSH SLOPE
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MOVE.L D0,-(SP) ;PUSH ASPECT
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_FixMul ;CALC SLOPE*ASPECT
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MOVE.L (SP)+,D0 ;GET RESULT SLOPE2
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CLR.W -(SP) ;ROOM FOR FCN RESULT
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MOVE.L D0,-(SP) ;PUSH SLOPE2
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JSR AngleFromSlope ;SCAN FOR ARCTAN
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MOVE (SP)+,D0 ;GET RESULT ANGLE
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TST D7 ;WAS DH POSITIVE ?
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BPL.S DONE ;YES, CONTINUE
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ADD #180,D0 ;NO, ADD 180 TO ANG
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CMP #360,D0 ;IS RESULT = 360 ?
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BNE.S DONE ;NO, CONTINUE
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ZERO CLR D0 ;YES, ANGLE := 0
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DONE MOVE.L ANGLE(A6),A0 ;GET VAR ADDR
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MOVE D0,(A0) ;STORE INTO ANGLE
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MOVEM.L (SP)+,D6-D7/A4 ;RESTORE REGS
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UNLINK PARAMSIZE,'PTTOANGL'
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.END
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