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Power-Programmierung
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CD1.mdf
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assemblr
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library
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sampler0
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feed.asm
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Assembly Source File
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1987-05-05
|
3KB
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117 lines
Name feed
Title feed
page ,132
comment /
This program is a filter that reads the parameter line
for a file spec. If it finds one it opens all matching
files and sends them to standard output. This is good
for processing more than one file, find, translat, etc.
/
;===================================================================
code segment public
;===================================================================
;
; command line is at 80h of psp - first byte is length
;
org 80h
;parmsize db ?
;parm db 7fh dup (?)
dta db 21 dup (?)
attrib db ?
ftime dw ?
fdate dw ?
fsize dd ?
fname db 13 dup (?) ; dta asciiz filename from dos.
;
; .com starts at 100h - but must jump around any data area
;
org 100h ; com file starts here
assume cs:code,ds:code,es:code
feed:
jmp clear
;===================================================================
;
; data area for .com programs
;
handle dw 0h ; assume standard input
bufsiz equ 255
buffer db bufsiz dup (?)
;
;===================================================================
clear:
;
; start of actual code is here (clear)
;
;
; now figure out which file to read from - parm line or standard input
;
cmp dta,0h ; if zero, no parm
jz nomore ; must have parm to read
;
; parm length is not zero - assume the parm is a file name. If not
; found, quit.
;
mov al,dta ; get size of parm
xor ah,ah ; zero out top part of accum.
mov si,ax ; use length as a pointer into the dta
mov [si]+dta+1,0h ; to tack on a zero byte (asciiz).
;
; Use the default dta at 80h. Find first matching filename.
;
lea dx,dta+2 ; address of 'filename'
xor cx,cx ; attributes of file - (normal)
mov ah,4Eh ; dos
int 21h ; invoke function
jc nomore ; error or no match - quit
;
; fname should now contain the first byte of an asciiz filename that
; matches the filespec from the parmline. open the file and send it
; to standard output.
;
again:
;
; open the file
;
lea dx,fname ; point at asciiz filename
mov al,0h ; open for reading
mov ah,3dh ; read function call
int 21h ; invoke dos
jc oops
mov handle,ax ; save file handle.
;
; now use the handle to read the file. AX will contain the # of
; characters returned from the file after the read.
; if ax=0 eof.
;
readloop:
mov bx,handle ; read from standard input or file
mov cx,bufsiz ; # of characters to read
lea dx,buffer ; seg:off address of buffer area
mov ah,3fh ; dos read function
int 21h ; invoke function
jc oops ; error!
cmp ax,0h ; if zero, end of file
jz oops
;
mov cx,ax ; cx (and ax) contain # characters read
lea si,buffer ; offset of buffer
;
mov bx,1h ; standard output device
mov ah,40h ; dos write function
int 21h ; invoke dos function
jmp readloop ; repeat until end of file or error
oops:
;
; end of file or access error
; jump to next filename
;
mov ah,4fh ; this call takes no input.
int 21h ; if carry set, no more files.
jnc again ; if no carry, go transfer this one
nomore:
int 20h ; return to dos
code ends
end feed