svga.asm

VESA 图形编程的汇编子程序库

procstart   __clear16

        push    bp                  ; Set up stack frame
        mov     bp,sp
        push    si                  ; Save registers
        push    di

; Setup graphics controller

        mov     dx,3CEh             ; DX := Graphics Controller I/O port

        mov     ah,0                ; AH := Background color
        xor     al,al               ; AL := 0 (Set/Reset register number)
        out     dx,ax               ; load set/reset register

        mov     ax,0F01h            ; AH := 1111b (mask for Enable set/reset)
                                    ; AL := 1 (enable Set/reset reg number)
        out     dx,ax               ; load enable set/reset reg

        mov     ax,[_maxy]
        inc     ax
        mul     [_bytesperline]     ; DX:AX := number of bytes to fill
        mov     bx,ax               ; BX := bytes in last bank to fill
        mov     dh,dl               ; DH := number of full banks to fill

        mov     ax,VGABufferSeg
        mov     es,ax
        mov     di,[OriginOffset]   ; ES:DI -> video buffer
        mov     ax,[BankOffset]     ; AX := starting bank number
        cld                         ; Moves go up in memory

        or      dh,dh               ; More than one bank to fill?
        jz      @@SingleBank        ; No, only fill a single bank

; Fill all of the full 64k banks first

@@OuterLoop:
        call    setBank
        mov     cx,4000h            ; Need to set 4000h double words per bank
    rep stosd
        inc     al
        dec     dh
        jnz     @@OuterLoop

; Now fill the last partial bank

@@SingleBank:
        call    setBank
        mov     cx,bx
        shr     cx,2                ; CX := number of double words to set
    rep stosd

; Restore graphics controller

        mov     dx,3CEh             ; DX := Graphics Controller I/O port
        xor     ax,ax               ; AH := 0, AL := 0
        out     dx,ax               ; Restore default Set/Reset register

        inc     ax                  ; AH := 0, AL := 1
        out     dx,ax               ; Restore enable Set/Reset register

        pop     di
        pop     si
        pop     bp
        ret

procend     __clear16

;----------------------------------------------------------------------------
; void clear256(void)
;----------------------------------------------------------------------------
; Routine to clear the screen. Assumes pages begin on bank boundaries
; for simplicity of coding.
;----------------------------------------------------------------------------
procstart   __clear256

        push    di
        mov     ax,[_maxy]
        inc     ax
        mul     [_bytesperline]     ; DX:AX := number of bytes to fill
        mov     bx,ax               ; BX := bytes in last bank to fill
        mov     dh,dl               ; DH := number of full banks to fill

        mov     ax,VGABufferSeg
        mov     es,ax
        mov     di,[OriginOffset]   ; ES:DI -> video buffer
        mov     dl,[BYTE BankOffset]; DL := starting bank number
        cld                         ; Moves go up in memory

        or      dh,dh               ; More than one bank to fill?
        jz      @@SingleBank        ; No, only fill a single bank

; Fill all of the full 64k banks first

@@OuterLoop:
        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,4000h            ; Need to set 4000h double words per bank
    rep stosd
        inc     dl
        dec     dh
        jnz     @@OuterLoop

; Now fill the last partial bank

@@SingleBank:
        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,bx
        shr     cx,2                ; CX := number of double words to set
    rep stosd

        pop     di
        ret

procend     __clear256

;----------------------------------------------------------------------------
; void clear32k(void)
;----------------------------------------------------------------------------
; Routine to clear the screen. Assumes pages begin on bank boundaries
; for simplicity of coding.
;----------------------------------------------------------------------------
procstart   __clear32k

        push    di
        mov     ax,[_maxy]
        inc     ax
        mul     [_bytesperline]     ; DX:AX := number of bytes to fill
        mov     bx,ax               ; BX := bytes in last bank to fill
        mov     dh,dl               ; DH := number of full banks to fill

        mov     ax,VGABufferSeg
        mov     es,ax
        mov     di,[OriginOffset]   ; ES:DI -> video buffer
        mov     dl,[BYTE BankOffset]; DL := starting bank number
        cld                         ; Moves go up in memory

; Fill all of the full 64k banks first

@@OuterLoop:
        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,4000h            ; Need to set 4000h double words per bank
    rep stosd
        inc     dl
        dec     dh
        jnz     @@OuterLoop

; Now fill the last partial bank

        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,bx
        shr     cx,2                ; CX := number of double words to set
    rep stosd

        pop     di
        ret

procend     __clear32k

;----------------------------------------------------------------------------
; void clear64k(void)
;----------------------------------------------------------------------------
; Routine to clear the screen. Assumes pages begin on bank boundaries
; for simplicity of coding.
;----------------------------------------------------------------------------
procstart   __clear64k

        push    di
        mov     ax,[_maxy]
        inc     ax
        mul     [_bytesperline]     ; DX:AX := number of bytes to fill
        mov     bx,ax               ; BX := bytes in last bank to fill
        mov     dh,dl               ; DH := number of full banks to fill

        mov     ax,VGABufferSeg
        mov     es,ax
        mov     di,[OriginOffset]   ; ES:DI -> video buffer
        mov     dl,[BYTE BankOffset]; DL := starting bank number
        cld                         ; Moves go up in memory

; Fill all of the full 64k banks first

@@OuterLoop:
        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,4000h            ; Need to set 4000h double words per bank
    rep stosd
        inc     dl
        dec     dh
        jnz     @@OuterLoop

; Now fill the last partial bank

        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,bx
        shr     cx,2                ; CX := number of double words to set
    rep stosd

        pop     di
        ret

procend     __clear64k

;----------------------------------------------------------------------------
; void clear16m(void)
;----------------------------------------------------------------------------
; Routine to clear the screen. Assumes pages begin on bank boundaries
; for simplicity of coding.
;----------------------------------------------------------------------------
procstart   __clear16m

        push    di
        mov     ax,[_maxy]
        inc     ax
        mul     [_bytesperline]     ; DX:AX := number of bytes to fill
        mov     bx,ax               ; BX := bytes in last bank to fill
        mov     dh,dl               ; DH := number of full banks to fill

        mov     ax,VGABufferSeg
        mov     es,ax
        xor     di,di               ; ES:DI -> video buffer
        mov     dl,[BYTE BankOffset]; DL := starting bank number
        cld                         ; Moves go up in memory

; Fill all of the full 64k banks first

@@OuterLoop:
        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,4000h            ; Need to set 4000h double words per bank
    rep stosd
        inc     dl
        dec     dh
        jnz     @@OuterLoop

; Now fill the last partial bank

        mov     al,dl
        call    setBank
        xor     eax,eax             ; Clear to black
        mov     cx,bx
        shr     cx,2                ; CX := number of double words to set
    rep stosd

        pop     di
        ret

procend     __clear16m

;----------------------------------------------------------------------------
; void _copyTest16(void)
;----------------------------------------------------------------------------
; Routine to copy the top half of video memory to the bottom half of
; video memory. To ensure that we a moving across a bank boundary in
; 16 color modes, we copy the data to the second video page.
;----------------------------------------------------------------------------
procstart   __copyTest16

        push    si                  ; Save registers
        push    di
        push    ds

        mov     ax,[_maxy]
        inc     ax
        shr     ax,1                ; AX := (Yres+1) / 2
        mul     [_bytesperline]
        mov     cx,ax               ; CX := Number of bytes to move

; Set up graphics controller

        mov     dx,3CEh             ; DX := Graphics Controller address port
        mov     ax,0105h            ; AH := 1 (read mode 0, write mode 1)
                                    ; AL := 5 (Mode register number)
        out     dx,ax               ; Set up mode

        mov     di,[WORD _pagesize] ; ES:DI := offset into destination buffer
        mov     ax,[WORD _pagesize+2]
        add     di,cx
        adc     al,0
        call    setBank             ; Set the read/write bank number

        xor     si,si               ; DS:SI := offset into source buffer
        xor     ax,ax
        call    setReadBank         ; Set the read bank number

        mov     ax,VGABufferSeg
        mov     ds,ax               ; DS:SI -> source buffer
        mov     es,ax               ; ES:DI -> destination buffer
        cld                         ; Moves go up in memory

    rep movsb                       ; Move all data in bank FAST!

; Restore default graphics controller state

        mov     ax,0005h            ; default mode register value
        out     dx,ax

        pop     ds
        pop     di
        pop     si
        ret

procend     __copyTest16

;----------------------------------------------------------------------------
; void _copyTest256(void)
;----------------------------------------------------------------------------
; Routine to copy the top half of video memory to the bottom half of
; video memory, to test moving data across bank boundaries using separate
; read/write banks. To simplify the coding we move the first 100 scan
; lines down to start at scanline 205. This ensure allows us to move data
; from bank 0 to bank 2 in 640x??? display modes.
;----------------------------------------------------------------------------
procstart   __copyTest256

        push    si                  ; Save registers
        push    di
        push    ds

        mov     ax,100
        mul     [_bytesperline]
        mov     cx,ax               ; CX := Number of bytes to move
        shr     cx,1                ; CX := Number of words to move

        mov     ax,205
        mul     [_bytesperline]
        mov     di,ax               ; DI := offset into destination bank
        mov     al,dl
        call    setBank             ; Set the read/write bank number

        xor     si,si               ; DS:SI := offset into source buffer