如何在装配图形模式下打印BMP图片文件

Question

所以我尝试从我在学校的学习书中复制代码来打印一个 bmp 文件，按照提到的方法做了所有事情，它只显示错误消息。谁能帮我调试？

代码：

IDEAL
MODEL small
STACK 100h
DATASEG
;================================
filename db 'test.bmp',0

filehandle dw ?

Header db 54 dup (0)

Palette db 256*4 dup (0)

ScrLine db 320 dup (0)

ErrorMsg db 'Error', 13, 10,'$'
;================================
CODESEG
;================================
proc OpenFile

    ; Open file

    mov ah, 3Dh
    xor al, al
    mov dx, offset filename
    int 21h

    jc openerror
    mov [filehandle], ax
    ret

    openerror:
    mov dx, offset ErrorMsg
    mov ah, 9h
    int 21h
    ret
endp OpenFile
proc ReadHeader

    ; Read BMP file header, 54 bytes

    mov ah,3fh
    mov bx, [filehandle]
    mov cx,54
    mov dx,offset Header
    int 21h
    ret
    endp ReadHeader
    proc ReadPalette

    ; Read BMP file color palette, 256 colors * 4 bytes (400h)

    mov ah,3fh
    mov cx,400h
    mov dx,offset Palette
    int 21h
    ret
endp ReadPalette
proc CopyPal

    ; Copy the colors palette to the video memory
    ; The number of the first color should be sent to port 3C8h
    ; The palette is sent to port 3C9h

    mov si,offset Palette
    mov cx,256
    mov dx,3C8h
    mov al,0

    ; Copy starting color to port 3C8h

    out dx,al

    ; Copy palette itself to port 3C9h

    inc dx
    PalLoop:

    ; Note: Colors in a BMP file are saved as BGR values rather than RGB.

    mov al,[si+2] ; Get red value.
    shr al,2 ; Max. is 255, but video palette maximal

    ; value is 63. Therefore dividing by 4.

    out dx,al ; Send it.
    mov al,[si+1] ; Get green value.
    shr al,2
    out dx,al ; Send it.
    mov al,[si] ; Get blue value.
    shr al,2
    out dx,al ; Send it.
    add si,4 ; Point to next color.

    ; (There is a null chr. after every color.)

    loop PalLoop
    ret
endp CopyPal

proc CopyBitmap

    ; BMP graphics are saved upside-down.
    ; Read the graphic line by line (200 lines in VGA format),
    ; displaying the lines from bottom to top.

    mov ax, 0A000h
    mov es, ax
    mov cx,200
    PrintBMPLoop:
    push cx

    ; di = cx*320, point to the correct screen line

    mov di,cx
    shl cx,6
    shl di,8
    add di,cx

    ; Read one line

    mov ah,3fh
    mov cx,320
    mov dx,offset ScrLine
    int 21h

    ; Copy one line into video memory

    cld 

    ; Clear direction flag, for movsb

    mov cx,320
    mov si,offset ScrLine
    rep movsb 

    ; Copy line to the screen
    ;rep movsb is same as the following code:
    ;mov es:di, ds:si
    ;inc si
    ;inc di
    ;dec cx
    ;loop until cx=0

    pop cx
    loop PrintBMPLoop
    ret
endp CopyBitmap
;================================
start:
mov ax, @data
mov ds, ax
;================================

    ; Graphic mode
    mov ax, 13h
    int 10h

    ; Process BMP file
    call OpenFile
    call ReadHeader
    call ReadPalette
    call CopyPal
    call CopyBitmap

    ; Wait for key press
    mov ah,1

    int 21h
    ; Back to text mode
    mov ah, 0
    mov al, 2
    int 10h
;================================
exit:
    mov ax, 4c00h
    int 21h
    END start

这是全部代码。

Answer 1

您需要合适的 .bmp 文件：

Name: test.bmp
Location: In the current directory
Width: 320
Height: 200
Colors: 256

收下这个（版权归我所有！免费使用！）：

右键单击图片并保存图片。使用 Irfanview 之类的工具将其重新格式化为 BMP，并将其重命名为 "test.bmp"。放在你启动程序的目录下。

如果你使用 DOSBox the picture is distorted since DOSBox "translates" the 320*200 video mode Int 10h AH=00h AL=13h 到它自己的屏幕分辨率，默认情况下是 4/3 模式（我猜是 640*480）。更改 dosbox-0.74.conf 中 windowresolution 的值在这里没有效果。 :-(

Answer 2

您照片的高度和宽度需要与您的高度和宽度参数相匹配。我建议将您的照片涂上油漆以检查那里的坐标。我试过了，它对我有用。

如何在装配图形模式下打印BMP图片文件

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