-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathpicture.asm
117 lines (110 loc) · 2.39 KB
/
picture.asm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
; -----
; A modified BMP file throw gimp
; gimp is able to show you the color pallet
; + you can rearrange the pallet to fit the project
; from gimp to mspaint to export again.
; -----
proc OpenFile
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 registers
; 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
proc RenderPic
;Process BMP file
call OpenFile
call ReadHeader
call ReadPalette
call CopyPal
call CopyBitmap
; Display the background picture
ret
endp RenderPic