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/ Games of Daze / Infomagic - Games of Daze (Summer 1995) (Disc 1 of 2).iso / x2ftp / msdos / libs / hobbes3 / line.asm < prev next >

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Assembly Source File | 1992-08-17 | 16.4 KB | 537 lines

include hobbes.inc include extrn.inc .DATA ; Plane masks for clipping left and right edges of rectangle. LeftClipPlaneMask db 00fh,00eh,00ch,008h RightClipPlaneMask db 001h,003h,007h,00fh .CODE ;-------------------------------------------------------------------------- ; void HLine( int X1, int X2, int Y, char COLOR ) ; void HLineClip( int X1, int X2, int Y, char COLOR ) ; public _HLineClip _HLineClip proc ARG X1:WORD, X2:WORD, Y:WORD, COLOR:WORD push bp mov bp,sp push ds mov ax,@data mov ds,ax mov ax,Y cmp ax,_ClipTop jl @@hlc_exit cmp ax,_ClipBottom jg @@hlc_exit mov ax,X1 cmp ax,_ClipRight jg @@hlc_exit cmp ax,_ClipLeft jge @@hlc_1 mov ax,_ClipLeft mov X1,ax @@hlc_1: mov ax,X2 cmp ax,_ClipLeft jl @@hlc_exit cmp ax,_ClipRight jle hlc_2 mov ax,_ClipRight mov X2,ax jmp short hlc_2 @@hlc_exit: pop ds pop bp ret _HLineClip endp public _HLine _HLine proc far push bp mov bp,sp push ds mov ax,@data mov ds,ax hlc_2: mov es,_ModeX_Segment ; point ES:DI to the left pixel's address push si push di cld mov di,Y shl di,1 mov di,word ptr _RowOffset[di] mov ax,X1 shr ax,2 ; X/4 = offset of pixel in scan line add di,ax ; final offset of pixel in page add di,_Display_Offset mov dx,SC_INDEX ; set the Sequence Controller Index to mov al,MAP_MASK ; point to the Map Mask register out dx,al inc dx ; point DX to the SC Data register mov si,X1 and si,0003h ; look up left edge plane mask mov bh,LeftClipPlaneMask[si] ; to clip & put in BH mov si,X2 and si,0003h ; look up right edge plane mov bl,RightClipPlaneMask[si] ; mask to clip & put in BL mov cx,X2 ; calculate # of addresses across line mov si,X1 and si,not 011b sub cx,si shr cx,2 ; # of addresses across line to draw - 1 jnz @@HL_MasksSet ; there's more than one byte to draw and bh,bl ; there's only one byte, so combine the left ; and right edge clip masks @@HL_MasksSet: mov ah,byte ptr COLOR mov al,bh ; put left-edge clip mask in AL out dx,al ; set the left-edge plane (clip) mask mov al,ah ; put color in AL stosb ; draw the left edge dec cx ; count off left edge byte js @@HL_Done ; that's the only byte jz @@HL_DoRtEdge ; there are only two bytes mov al,00fh ; middle addresses are drawn 4 pixels at a pop out dx,al ; set the middle pixel mask to no clip mov al,ah ; put color in AL shr cx,1 rep stosw ; draw the middle addresses four pixels apiece adc cx,0 rep stosb @@HL_DoRtEdge: mov al,bl ; put right-edge clip mask in AL out dx,al ; set the right-edge plane (clip) mask mov al,ah ; put color in AL stosb ; draw the right edge @@HL_Done: pop di ; restore caller's register variables pop si pop ds pop bp ; restore caller's stack frame ret _HLine endp ;----------------------------------------------------------------------- ; void VLine( int X, int Y1, int Y2, char COLOR ) ; void VLineClip( int X, int Y1, int Y2, char COLOR ) ; public _VLineClip _VLineClip proc ARG X:WORD, Y1:WORD, Y2:WORD, COLOR:WORD push bp mov bp,sp push ds mov ax,@data mov ds,ax mov ax,X cmp ax,_ClipLeft jl @@vlc_exit cmp ax,_ClipRight jg @@vlc_exit mov ax,Y1 cmp ax,_ClipBottom jg @@vlc_exit cmp ax,_ClipTop jge @@vlc_1 mov ax,_ClipTop mov Y1,ax @@vlc_1: mov ax,Y2 cmp ax,_ClipTop jl @@vlc_exit cmp ax,_ClipBottom jle vlc_2 mov ax,_ClipRight mov Y2,ax jmp short vlc_2 @@vlc_exit: pop ds pop bp ret _VLineClip endp public _VLine _VLine proc far push bp mov bp,sp push ds mov ax,@data mov ds,ax vlc_2: mov es,_ModeX_Segment ; put video segment in ES mov cl,byte ptr X ; set the drawing plane for the vline and cl,011b ; CL = vline's plane mov ax,0100h+MAP_MASK ; AL = index in SC of Map Mask reg shl ah,cl ; set only the bit for the vline's plane to 1 mov dx,SC_INDEX ; set the Map Mask to enable only out dx,ax ; the vline's plane mov bx,Y1 ; compute the starting address of the vline shl bx,1 mov bx,word ptr _RowOffset[bx] mov ax,X shr ax,2 ; X/4 = offset of pixel in scan line add bx,ax ; final offset of pixel in page add bx,_Display_Offset ; adjust for current page mov cx,Y2 sub cx,Y1 ; compute number of pixels in line - 1 mov al,byte ptr COLOR @@vl_loop: mov es:[bx],al ; set the current pixel add bx,_Virtual_Width_Addr ; jump to the pixel below dec cx ; decrement the counter jge @@vl_loop ; loop until less than zero pop ds pop bp ret _VLine endp ;----------------------------------------------------------------------- ; void HLineR( int X1, int X2, int Y, char COLOR ) ; void HLineClipR( int X1, int X2, int Y, char COLOR ) ; ; Draws a horizontal line from (X1, Y) to (X2, Y). ; Uses Watcom Parameter passing convention in registers ; ; X1 in AX ; X2 in DX ; Y in CX ; Color in BX public _HLineClipR _HLineClipR proc push ds push @data pop ds cmp cx,_ClipTop jl @@hlc_exitR cmp cx,_ClipBottom jg @@hlc_exitR cmp ax,_ClipRight jg @@hlc_exitR cmp ax,_ClipLeft jge @@hlc_1R mov ax,_ClipLeft @@hlc_1R: cmp dx,_ClipLeft jl @@hlc_exitR cmp dx,_ClipRight jle hlc_2R mov dx,_ClipRight jmp short hlc_2R @@hlc_exitR: pop ds ret _HLineClipR endp public _HLineR _HLineR proc far push ds push @data pop ds hlc_2R: mov es,_ModeX_Segment ; point ES:DI to the left pixel's address push si push di cld mov di,cx shl di,1 mov di,word ptr _RowOffset[di] mov si,ax shr si,2 ; X/4 = offset of pixel in scan line add di,si ; final offset of pixel in page add di,_Display_Offset ; adjust for current page mov cx,bx mov si,ax and si,0003h ; look up left edge plane mask mov bh,LeftClipPlaneMask[si] ; to clip & put in BH mov si,dx and si,0003h ; look up right edge plane mov bl,RightClipPlaneMask[si] ; mask to clip & put in BL mov si,ax mov ah,cl ; Get the Color for later mov cx,dx ; calculate # of addresses across line ; DI-~Y,SI-X1,AH-C,CX-X2,BX-mask ; AL,DX mov dx,SC_INDEX ; set the Sequence Controller Index to mov al,MAP_MASK ; point to the Map Mask register out dx,al inc dx ; point DX to the SC Data register and si,not 011b sub cx,si shr cx,2 ; # of addresses across line to draw - 1 jnz @@HL_MasksSetR ; there's more than one byte to draw and bh,bl ; there's only one byte, so combine the left ; and right edge clip masks @@HL_MasksSetR: mov al,bh ; put left-edge clip mask in AL out dx,al ; set the left-edge plane (clip) mask mov al,ah ; put color in AL stosb ; draw the left edge dec cx ; count off left edge byte js @@HL_DoneR ; that's the only byte jz @@HL_DoRtEdgeR ; there are only two bytes mov al,00fh ; middle addresses are drawn 4 pixels at a pop out dx,al ; set the middle pixel mask to no clip mov al,ah ; put color in AL shr cx,1 rep stosw ; draw the middle addresses four pixels apiece adc cx,0 rep stosb @@HL_DoRtEdgeR: mov al,bl ; put right-edge clip mask in AL out dx,al ; set the right-edge plane (clip) mask mov al,ah ; put color in AL stosb ; draw the right edge @@HL_DoneR: pop di pop si pop ds ret _HLineR endp ;----------------------------------------------------------------------- ; void Line( int X1, int Y1, int X2, int Y2, int COLOR ) public _Line _Line proc ARG X1:WORD, Y1:WORD, X2:WORD, Y2:WORD, COLOR:WORD push bp mov bp,sp push ds mov ax,@data mov ds,ax mov es,_ModeX_Segment push si push di mov ax,_Virtual_Width_Addr mov byte ptr cs:mod_3+2,al mov byte ptr cs:mod_6+2,al mov ax,X1 sub ax,X2 ; compute ax=DX=|X1-X2| jge short line_1 neg ax line_1: mov si,Y1 sub si,Y2 ; compute si=DY=|Y1-Y2| jge short line_2 neg si line_2: cmp si,ax jle line_small_slope jmp line_big_slope line_small_slope: ; DX>=DY mov cx,si ; cx=DY shl si,1 ; si=2DY mov cs:(mod_1-2),si ; CONST1=2DY>=0 (need segment override?) sub cx,ax ; cx=DY-DX shl cx,1 ; cx=2(DY-DX) mov cs:(mod_2-2),cx ; CONST2=2(DY-DX)<=0 sub si,ax ; parameter si=P=2DY-DX mov di,X1 ; these should probably go at the top where mov bx,X2 ; X1,X2 are first loaded from the stack cmp di,bx jl short line_3 ; mov di,bx ; X1>X2, so di has starting x value (X2) mov bx,Y2 ; bx has starting y value (Y2) cmp bx,Y1 jl line_2_add_y mov word ptr cs:mod_3,0EF83h ; Hex for sub di,(immediate) jmp short line_2_3_again line_2_add_y: mov word ptr cs:mod_3,0C783h ; Hex for add di,(immediate) jmp short line_2_3_again line_3: ; X1<X2, so di has starting x value (X1) mov bx,Y1 ; bx has starting y value (Y1) cmp bx,Y2 jl line_3_add_y mov word ptr cs:mod_3,0EF83h ; Hex for sub di,(immediate) jmp short line_2_3_again line_3_add_y: mov word ptr cs:mod_3,0C783h ; Hex for add di,(immediate) line_2_3_again: shl bx,1 ; index into big RowOffset table to get mov bx,word ptr _RowOffset[bx] ; scan line address mov cx,di ; save X for computation of MapMask shr di,2 ; add offset (X/4) of pixel in scan line add di,bx ; and store in di mov bx,ax ; save count DX ; Our story so far: ; si = P ; bx = DX ; ax = DX ; cx = min(X1,X2) ; di = pixel address ; dx = ? and cl,011b ; cl = pixel's plane mov ax,1100h+MAP_MASK ; al = index in SC of Map Mask reg shl ah,cl ; set only the bit for the pixel's plane to 1 mov cx,bx ; restore count to cx mov dx,SC_INDEX ; set the Map Mask to enable only ; the pixel's plane mov bl,byte ptr COLOR jmp short line_set_pixel line_loop1: rol ah,1 ; next x adc di,0 cmp si,0 jge line_neg_p1 add si,2112h ; next p ; SELF-MODIFYING (replace 0000 with CONST1) mod_1 label word ; label for modification jmp short line_set_pixel mod_3 label word line_neg_p1: add di,80 ; next y (add or subtract row width) ; SELF-MODIFYING (add/sub) add si,4269h ; next p ; SELF-MODIFYING (replace 0000 with CONST2) mod_2 label word ; label for modification line_set_pixel: out dx,ax mov es:[di],bl ; set the pixel (no segment override?) dec cx jge line_loop1 jmp line_done line_big_slope: ; DY>DX mov bx,ax ; bx=DX shl ax,1 ; ax=2DX mov cs:(mod_4-2),ax ; CONST1=2DX>=0 mov dx,si ; dx=DY shl si,1 ; si=2DY sub ax,si ; ax=2(DX-DY) mov cs:(mod_5-2),ax ; CONST2=2(DX-DY)<=0 mov si,ax ; si=2DX-2DY add si,dx ; si=P=2DX-DY mov di,X1 ; these should probably go at the top where mov bx,X2 ; X1,X2 are first loaded from the stack cmp di,bx jl short line_6 ; mov di,bx ; X1>=X2, so di has starting x value (X2) mov bx,Y2 ; bx has starting y value (Y2) cmp bx,Y1 jl line_5_add_y mov word ptr cs:mod_6,0EF83h ; Hex for sub di,(immediate) jmp short line_5_6_again line_5_add_y: mov word ptr cs:mod_6,0C783h ; Hex for add di,(immediate) jmp short line_5_6_again line_6: ; X1<X2, so di has starting x value (X1) mov bx,Y1 ; bx has starting y value (Y1) cmp bx,Y2 jl line_6_add_y mov word ptr cs:mod_6,0EF83h ; Hex for sub di,(immediate) jmp short line_5_6_again line_6_add_y: mov word ptr cs:mod_6,0C783h ; Hex for add di,(immediate) line_5_6_again: shl bx,1 ; index into big RowOffset table to get mov bx,word ptr _RowOffset[bx] ; scan line address mov cx,di ; save X for computation of MapMask shr di,2 ; add offset (X/4) of pixel in scan line add di,bx ; and store in di ; Our story so far: ; si = P ; bx = address ; ax = CONST2 ; cx = DY ; di = pixel address ; dx = DY and cl,011b ; cl = pixel's plane mov ax,1100h+MAP_MASK ; al = index in SC of Map Mask reg shl ah,cl ; set only the bit for the pixel's plane to 1 mov cx,dx ; restore count to cx mov bl,byte ptr COLOR mov dx,SC_INDEX ; set the Map Mask to enable only ; the pixel's plane jmp short line_loop_enter_2 mod_6 label word line_loop2: add di,80 ; next y (add or subtract row width) ; SELF-MODIFYING (add/sub) cmp si,0 jge line_neg_p2 add si,2001 ; next p ; SELF-MODIFYING (replace 0000 with CONST1) mod_4 label word ; label for modification jmp short line_set_pixel2 line_neg_p2: rol ah,1 ; next x adc di,0 add si,0Bach ; next p ; SELF-MODIFYING (replace 0000 with CONST2) mod_5 label word ; label for modification line_loop_enter_2: out dx,ax line_set_pixel2: mov es:[di],bl ; set the pixel dec cx jge line_loop2 line_done: pop di ; restore caller's register variables pop si pop ds pop bp ; restore caller's stack frame ret _Line endp ;---------------------------------------------------------------------------- END