HPAVC/HPAVC CD-ROM.iso/pc/PCACHSRC.ZIP/PCX2SCRN.ASM

Assembly Source File | 1991-04-14 | 4.9 KB | 255 lines

;PCX2SCRN.COM
;invoke by--  PCX2SCRN <enter>
;version 20/3 has filespec DEMO.PCX inside this program.
;displays the pcx file on an ega or vga (mode-16) screen.
;
comseg segment
 org 100h
 assume DS:comseg, CS:comseg
main proc far
     jmp     start

handle        dw     2        ;file handle.
screenaddr    dw    0,0A000h    ;starting addr video-RAM, current line.
screenend        dw    350*80,0A000h    ;ending addr video-RAM.
header        db     128 dup(0)    ;pcx header read into here.
buffer        db    200 dup(0)    ;pcx file read into here.
bufferptr        dw    0            ;pointer into buffer.
cnt16        dw    0        ;palette register
cnt3            dw    0
cnt            dw    0
colour        dw    0
bitplane        dw    0
count        dw    0
content        dw    0
lineoffset    dw    0        ;offset in video-RAM, current line.
filespec      db    "temp.pcx",0    ;*****temporarily added.

MSG1        DB    "Cannot open PCX file $"    ;****$ inserted
MSG2        DB    "Cannot read header $"
closemsg    db    "Cannot close PCX file $"

colourmasks    DW    00H
    DW    08H
    DW    01H
    DW    09H

start:
    mov ah,3Dh        ;open the file.
    mov dx,offset filespec
    mov al,0
    int 21h
    jc  openerror
    mov handle,ax        ;handle
    jmp short noerror
openerror:
    mov dx,offset MSG1
    mov ah,9
    int 21h
    jmp exitprog
noerror:

;***read & check the header...
 mov bx,handle        ;filehandle
 mov cx,128
 mov dx,offset header
 mov ah,3Fh
 int 21h            ;read file
 jc  readerror
    cmp    BYTE PTR header,10
    je    place1

readerror:
 mov dx,offset MSG2
 mov ah,9
 int 21h
 jmp exitprog

place1:
;******should put checking if mode 16 supported.
 mov ah,0
 mov al,16
 int 10h        ;mode 16
    mov    WORD PTR cnt16,0
    jmp    SHORT place4

place2:                    ;set ega palette....
    mov    si,WORD PTR cnt16
    mov    ax,si
    shl    si,1
    add    si,ax
    mov    bx,WORD PTR cnt3
    mov    al,BYTE PTR header[bx+16][si]
    mov    cl,6
    sar    al,cl
    and    ax,3
    mov    si,ax
    mov    WORD PTR cnt,si
    shl    si,1
    mov    ax,WORD PTR colourmasks[si]
    mov    cl,2
    sub    cl,bl
    shl    ax,cl
    or    WORD PTR colour,ax
    inc    WORD PTR cnt3
place3:
    cmp    WORD PTR cnt3,3
    jl    place2

 mov ah,16        ;set palette registers...
 mov al,0            ;set individual palette register.
 mov bh,BYTE PTR colour    ;value.
 mov    bl,BYTE PTR cnt16    ;which register.
 int 10h

    inc    WORD PTR cnt16
place4:
    cmp    WORD PTR cnt16,16
    jge    place5        ;to end of outer for-loop...

    sub    ax,ax
    mov    WORD PTR colour,ax
    mov    WORD PTR cnt3,ax
    jmp    SHORT place3
place5:            ;end of outer loop.

;***select initial colour plane...
    mov    ax,2
    mov    dx,03C4h        ;port 03C4h
    out    dx, al

    mov    ax,1
    mov    dx,03C5h        ;port 03C5h
    out    dx, al

    mov    ax,0
    mov    WORD PTR screenaddr,ax
    mov    dx,0A000h        ;top left byte of scrn mem
    mov    WORD PTR screenaddr+2,dx
    mov    ax,350*80
    mov    WORD PTR screenend,ax
    mov    dx,0A000h        ;end of scrn.
    mov    WORD PTR screenend+2,dx
    sub    ax,ax
    mov    WORD PTR lineoffset,ax
    mov    WORD PTR content,ax
    mov    WORD PTR count,ax
    mov    WORD PTR bitplane,1
    mov    WORD PTR bufferptr,200

;***graphics data loop...
place6:
    mov    ax,WORD PTR screenaddr
    mov    dx,WORD PTR screenaddr+2
    cmp    WORD PTR screenend,ax
    jne    place7
    cmp    WORD PTR screenend+2,dx
    jne    place7
    jmp    place15

place7:            ;start of the large not-end-mem loop
    cmp    WORD PTR bufferptr,200
    jne    place8
    mov    WORD PTR bufferptr,0

 mov bx, handle
 mov cx,200
 mov dx,offset buffer
 mov ah,3Fh
 int 21h                    ;read file

place8:            ;***loop counter or data byte?
    mov    bx,WORD PTR bufferptr
    mov    al,BYTE PTR buffer[bx]
    cbw
    mov    WORD PTR count,ax
    inc    WORD PTR bufferptr
    mov    al,BYTE PTR count
    and    ax,192
    cmp    ax,192
    jne    place10

    cmp    WORD PTR bufferptr,200    ;third inner IF....
    jne    place9
    mov    WORD PTR bufferptr,0
 mov bx, handle        ;file read...
 mov cx,200
 mov dx,offset buffer
 mov ah,3Fh
 int 21h                    ;read file

place9:                    ;
    mov    bx,WORD PTR bufferptr
    mov    al,BYTE PTR buffer[bx]
    cbw
    mov    WORD PTR content,ax
    inc    WORD PTR bufferptr
    and    WORD PTR count,63
    jmp    SHORT place11        ;jump around the else-condition...
    nop

place10:
    mov    ax,WORD PTR count
    mov    WORD PTR content,ax
    mov    WORD PTR count,1

place11:
    mov    ax,WORD PTR count
    dec    WORD PTR count
    or    ax,ax
    jne    place12
    jmp    place6
place12:
    mov    al,BYTE PTR content
    les    bx,DWORD PTR screenaddr
    mov    si,WORD PTR lineoffset
    mov    BYTE PTR es:[bx][si],al

    inc    WORD PTR lineoffset
    cmp    WORD PTR lineoffset,80
    jne    place11
    mov    WORD PTR lineoffset,0

    cmp    WORD PTR bitplane,8
    jne    place13
    add    WORD PTR screenaddr,80
    mov    WORD PTR bitplane,1
    jmp    SHORT place14
    nop
place13:                ;***else condition...
    shl    WORD PTR bitplane,1
place14:
    mov    ax,WORD PTR bitplane
    mov    dx,03C5h        ;port 03C5h
    out    dx, al

    jmp    SHORT place11    ;three loops close here.
    nop

place15:                ;***finished
 mov bx, handle
 mov ah,3Eh
 int 21h                ;close file
 jnc  nocloseerror
 mov dx,offset closemsg
 mov ah,9
 int 21h
 jmp short exitprog
nocloseerror:
 mov ah,2                ;beep and wait for keypress....
 mov dl,07
 int 21h
 mov ah,0
 int 16h

 mov ah,0
 mov al,3
 int 10h                    ;back to text mode 3

exitprog:
 mov ax,4C00h
 int 21h        ;exit
main    ENDP
comseg ends
 END main