C/C++ Users Group Library 1996 July

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Wrap

Assembly Source File | 1988-03-28 | 9.8 KB | 314 lines

page 80,132 page ; ; EGA Graphic Primitive for Microsoft C 3.0, Version 01APR86. ; (C) 1986 by Kent Cedola, 2015 Meadow Lake Ct., Norfolk, VA, 23518 ; towork equ 4 fmwork equ 6 towk equ -20 tox equ -18 toy equ -16 tow equ -14 toh equ -12 fmwk equ -10 fmx equ -8 fmy equ -6 fmw equ -4 fmh equ -2 needed equ 20 ; Amount of temporary space needed xorigin equ 2 yorigin equ 4 width equ 6 height equ 8 x equ 10 y equ 12 w equ 14 h equ 16 aspect1 equ 18 aspect2 equ 20 dgroup group _data _data segment word public 'data' assume ds:dgroup public _gdxmax,_gdxscale,_gdymax,_gdyscale _gdxmax dw 1024 _gdxscale db 1024 dup(0) _gdymax dw 1024 _gdyscale db 1024 dup(0) _data ends _text segment byte public 'code' assume cs:_text,ds:dgroup public _gpbitblt extrn _xpcpywtg:near ; extrn _xpcpywtw:near,_xpcpywtg:near,_xpcpywtd:near,_xpcpywtp:near ; extrn _xpcpygtw:near,_xpcpygtg:near,_xpcpygtd:near,_xpcpygtp:near ; extrn _xpcpydtw:near,_xpcpydtg:near,_xpcpydtd:near,_xpcpydtp:near _gpbitblt proc near push bp mov bp,sp sub sp,needed ; Reserve space for temp. variables fmparm: mov bx,[bp+fmwork] ; Load pointer to 'from' work parameters cmp byte ptr[bx+1],0 ; Check for 'from' workspace jne fmarea ; No, jump to 'from' workarea code fmspace: mov ax,[bx+x] ; Compute 'from' true X coordinate cmp ax,[bx+width] ; ... jae wkerror ; ... mov [bp+fmx],ax ; ... mov ax,[bx+y] ; Compute 'from' true Y coordinate cmp ax,[bx+height] ; ... jae wkerror ; ... mov [bp+fmy],ax ; ... jmp short fmcont fmarea: mov ax,[bx+xorigin] ; Compute 'from' true X coordinate add ax,[bx+x] ; ... cmp ax,[bx+width] ; ... jae wkerror ; ... mov [bp+fmx],ax ; ... mov ax,[bx+yorigin] ; Compute 'from' true Y coordinate add ax,[bx+y] ; ... cmp ax,[bx+height] ; ... jae wkerror ; ... mov [bp+fmy],ax ; ... fmcont: mov ax,[bx+width] ; Compute 'from' true width sub ax,[bp+fmx] ; ... cmp ax,[bx+w] ; ... jbe fmar01 ; ... mov ax,[bx+w] ; ... fmar01: ; ... mov [bp+fmw],ax ; ... mov ax,[bx+height] ; Compute 'from' true height sub ax,[bp+fmy] ; ... cmp ax,[bx+h] ; ... jbe fmar02 ; ... mov ax,[bx+h] ; ... fmar02: ; ... mov [bp+fmh],ax ; ... jmp short toparm wkerror: jmp fullclip toparm: mov bx,[bp+towork] ; Load pointer to 'to' work parameters cmp byte ptr [bx+1],0 ; Check for 'to' workspace jne toarea ; No, jump to 'to' workarea code tospace: mov ax,[bx+x] ; Compute 'to' true X coordinate cmp ax,[bx+width] ; ... jae wkerror ; ... mov [bp+tox],ax ; ... mov ax,[bx+y] ; Compute 'to' true Y coordinate cmp ax,[bx+height] ; ... jae wkerror ; ... mov [bp+toy],ax ; ... jmp short tocont toarea: mov ax,[bx+xorigin] ; Compute 'to' true X coordinate add ax,[bx+x] ; ... cmp ax,[bx+width] ; ... jae wkerror ; ... mov [bp+tox],ax ; ... mov ax,[bx+yorigin] ; Compute 'to' true Y coordinate add ax,[bx+y] ; ... cmp ax,[bx+height] ; ... jae wkerror ; ... mov [bp+toy],ax ; ... tocont: mov ax,[bx+w] ; If both width and height are zero then or ax,[bx+h] ; use 'from' width and height values jne toar01 ; No, jump over zero w,h code mov ax,[bp+fmw] ; Copy 'from' width and height to 'to' mov [bp+tow],ax ; widht and height mov ax,[bp+fmh] ; ... mov [bp+toh],ax ; ... jmp short toar04 ; ... toar01: cmp ax,0 ; If the width is zero then compute it jnz toar02 ; from the 'from' / 'to' height ratio mov ax,[bx+h] ; ... mul word ptr [bp+fmw] ; ... div word ptr [bp+fmh] ; ... mul word ptr [bx+aspect1] ; ... div word ptr [bx+aspect2] ; ... toar02: ; ... mov [bp+tow],ax ; ... mov ax,[bx+h] ; If the height is zero then compute it cmp ax,0 ; from the 'from' / 'to' width ratio jnz toar03 ; ... mov ax,[bx+w] ; ... mul word ptr [bp+fmh] ; ... div word ptr [bp+fmw] ; ... mul word ptr [bx+aspect2] ; ... div word ptr [bx+aspect1] ; ... toar03: ; ... mov [bp+toh],ax ; ... toar04: mov ax,[bx+width] ; Compute 'to' true width sub ax,[bp+tox] ; ... cmp ax,[bp+tow] ; ... jge toar05 ; ... mov [bp+tow],ax ; ... toar05: mov ax,[bx+height] ; Compute 'to' true height sub ax,[bp+toy] ; ... cmp ax,[bp+toh] ; ... jge toar06 ; ... mov [bp+toh],ax ; ... toar06: ; Build slope array push ds pop es pop si pop di lea di,dgroup:_gdxscale mov bx,[bp+fmw] mov dx,[bp+tow] call _gpslope lea di,dgroup:_gdyscale mov bx,[bp+fmh] mov dx,[bp+toh] call _gpslope pop di pop si ; Determine which routines to call for pixel copy. mov bx,[bp+towork] mov [bp+towk],bx mov al,[bx] shl al,1 shl al,1 mov bx,[bp+fmwork] mov [bp+fmwk],bx or al,[bx] xor bh,bh mov bl,al shl bx,1 add bx,offset _text:vectable call cs:[bx] jmp short theend fullclip: mov ax,-2 jmp short done theend: xor ax,ax done: mov sp,bp ; Restore the stack pop bp ret vectable dw offset _text:_xpcpywtw dw offset _text:_xpcpywtg dw offset _text:_xpcpywtd dw offset _text:_xpcpywtp dw offset _text:_xpcpygtw dw offset _text:_xpcpygtg dw offset _text:_xpcpygtd dw offset _text:_xpcpygtp dw offset _text:_xpcpydtw dw offset _text:_xpcpydtg dw offset _text:_xpcpydtd dw offset _text:_xpcpydtp _xpcpywtw: _xpcpywtd: _xpcpywtp: _xpcpygtw: _xpcpygtg: _xpcpygtd: _xpcpygtp: _xpcpydtw: _xpcpydtg: _xpcpydtd: _xpcpydtp: ret _gpbitblt endp _gpslope proc near ; DI = address of slope ; BX = X1 ; DX = X2 ; ES = DS cmp dx,bx je line ja octant2 octant1: mov cx,bx dec cx mov si,bx ; Error Register = -DX/2 shr si,1 ; ... neg si ; ... octant1L: add si,dx js octant1E sub si,bx inc al octant1E: stosb xor al,al loop octant1L ret octant2: mov byte ptr [di],0 mov cx,dx dec cx mov si,dx ; Error Register = -DY/2 ; shr si,1 ; ... neg si ; ... octant2L: inc byte ptr [di] add si,bx js octant2E sub si,dx inc di mov byte ptr [di],0 octant2E: loop octant2L inc byte ptr [di] ret line: mov al,1 mov cx,bx rep stosb ret _gpslope endp _text ends end