140 lines
2.2 KiB
Plaintext
140 lines
2.2 KiB
Plaintext
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; FLIP.A -- code to flip the screen. This version for the PC.
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VIDEO equ 10h
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dseg
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public flipok_
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flipok_ db 1 ;flag to say flip is supported
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screen_save dw 0
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screen_at dw 0
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screen_len dw 0
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curmode db 0
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curpage db 0
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curloc dw 0
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addr_6845 dw 3D4H
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cseg
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public scr_clr_
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; FLIPINIT -- initilize for flipping the screen.
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; paragraphs needed for screen image = flipinit();
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public flipinit_
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flipinit_:
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push bp
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mov screen_save,ds
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mov ah,15
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int VIDEO
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cmp al,7 ;monocrome ?
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jz monoinit
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mov screen_at,0b800h ;16k screen at b800
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mov screen_len,1024*8
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mov ax,1024 ;paragraphs needed to save
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pop bp
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ret
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monoinit:
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mov addr_6845,03b4h ;base of 6845
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mov screen_at,0b000h ;4k screen at b000
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mov screen_len,1024*2
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mov ax,256 ;paras needed to save
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pop bp
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ret
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; SCR_SAVE -- save the screen. use screen_at.
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public scr_save_
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scr_save_:
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push bp
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mov bp,sp
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mov ah,15
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int VIDEO
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mov curmode,al
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mov curpage,bh
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mov ah,3
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int VIDEO
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mov curloc,dx
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call disable_video
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push ds
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mov es,screen_save ;save the screen
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mov cx,screen_len
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mov ds,screen_at ;from here
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xor si,si
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mov di,si
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cld
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rep movsw
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pop ds
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call enable_video
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mov al,curmode
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cmp al,7 ;dont set monocrome mode
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jz clear_only
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cmp al,3
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jz clear_only
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mov ah,0
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mov al,3
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int VIDEO
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jmp saved
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clear_only:
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call scr_clr_
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saved: pop bp
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ret
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; SCR_REST -- restore the screen. use screen_at.
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public scr_rest_
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scr_rest_:
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push bp
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mov bp,sp
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mov al,curmode
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cmp al,7
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jz dorest
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mov ah,0
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int VIDEO ;restore the mode
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dorest:
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call disable_video
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push ds
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mov es,screen_at ;restore the screen
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mov cx,screen_len
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mov ds,screen_save ;to here
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xor si,si
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mov di,si
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cld
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rep movsw
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pop ds
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call enable_video
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mov ah,5
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mov al,curpage
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int VIDEO
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mov ah,2
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mov bh,curpage
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mov dx,curloc
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int VIDEO
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pop bp
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ret
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disable_video: ; turn the screen refresh off
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mov dx,addr_6845
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add dx,4
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mov al,25H
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out dx,al ; disable video
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ret
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enable_video: ; set crt mode
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mov dx,addr_6845
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add dx,4
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mov bx,40H
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mov es,bx
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mov al,es:[65H] ; crt_mode_set
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out dx,al ; restore video
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ret
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