mirror of https://github.com/nmlgc/ReC98.git
124 lines
2.3 KiB
NASM
124 lines
2.3 KiB
NASM
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PAGE 98,120
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; graphics - cutline
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;
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; DESCRIPTION:
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; 直線のクリッピング
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;
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; Function/Procedure:
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; curline : near
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; Parameters:
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; BL : o1
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; CX : x1
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; DI : y1 - ClipYT
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; BH : o2
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; SI : x2
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; BP : y2 - ClipYT
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; Returns:
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; BL,CX,DI ( o1,x1,y1 )はクリッピングにより変化する場合がある
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; BH,SI,BP ( o2,x2,y2 )は変化しない。
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; AX,DX は破壊
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;
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; Binding Target:
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; MASM 5.0 / OPTASM / TASM
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;
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; Running Target:
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; 80186/V30/80286...
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;
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; REQUIRING RESOURCES:
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; CPU: V30
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;
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; COMPILER/ASSEMBLER:
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; TASM 3.0
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; OPTASM 1.6
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;
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; NOTES:
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; ・grc_setclip()によるクリッピングに対応しています。
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;
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; AUTHOR:
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; 恋塚昭彦
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;
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; 関連関数:
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; grc_setclip()
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;
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; HISTORY:
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; 92/7/27 Initial: gc_line.asmから分離
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clipasm equ 1
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; カットカット〜〜〜(x1,y1)を切断により変更する
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; in: BH:o2, BL:o1
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; out: BH:o2, BL:o1, o1がzeroならば zflag=1
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public cutline
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cutline proc near
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; +-----+-----+-----+-----+-----+-----+-----+
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; !AH AL!DH DL!BH BL!CH CL! SI ! DI ! BP !
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; ! ! !o2:o1! x1 ! x2 ! y1 ! y2 !
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; +-----+-----+-----+-----+-----+-----+-----+
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or BL,BL
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jz short @@CUTRET
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test BL,YOKO_OUT
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jz short @@CUTTATE
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test BL,LEFT_OUT
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jz short @@CUTAR
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mov AX,ClipXL
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jmp short @@CUTAE
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EVEN
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@@CUTAR:
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mov AX,ClipXR
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@@CUTAE:
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sub CX,SI ; CX=x1-x2
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jz short @@CUTRET
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mov DX,DI ; DX=y1-y2
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sub DX,BP ;
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mov DI,AX ; DI=x1'
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sub AX,SI ; AX = (x1'-x2)
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imul DX ; * dy
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idiv CX ; / dx
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add AX,BP ; + y2
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mov CX,DI ; CX=x1'
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mov DI,AX ; DI=y1'
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xor AX,AX
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or DI,DI
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js short @@CUTBE
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mov AX,ClipYH
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cmp DI,AX
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jg short @@CUTBE
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@@CUTIN: xor BL,BL ; この点は中に入ったぜ
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@@CUTRET: or BX,BX ; もう完全に中にはいったかどうかをz flagで返す
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ret
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EVEN
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@@CUTTATE:
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xor AX,AX
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test BL,BOTTOM_OUT
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jz short @@CUTBE
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mov AX,ClipYH
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@@CUTBE:
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sub DI,BP ; DI=y1-y2
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jz short @@CUTRET
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mov DX,CX ; DX=x1-x2
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sub DX,SI ;
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mov CX,AX ; CX=y1'
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sub AX,BP ; AX = (y1'-y2)
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imul DX ; * dx
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idiv DI ; / dy
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add AX,SI ; + x2
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mov DI,CX ; DI=y1'
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mov CX,AX ; CX=x1'
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cmp ClipXL,CX
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jle short @@CUTBE1
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mov BL,LEFT_OUT ; 上ではじいてるから, zflagは 0 だよ
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ret ; ここにもリターンが!!
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EVEN
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@@CUTBE1: cmp CX,ClipXR
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jle short @@CUTIN
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mov BL,RIGHT_OUT ; ここも zflag=0
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ret ; ここにもリターンが!!
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EVEN
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cutline endp
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