(Assembly source code) print file program (print files)

INTRODUCTION

The following example is a simple program to read a file and print the contents to a standard printer. It gets the filename of the file to print from the DOS command prompt input line. The prompt input information is passed to the "program" in a buffer area of the "program Segment Prefix (PSP). The address of the "program Segment Prefix are passed to the" in the "ES and DS registers when the" program execution s Tarts. This is the program checks the keyboard between every character printed for an escape key code to terminate execution of the prog Ram.

; This program prints a file defined on the command line
. MODEL Small
; ************* Stack Section *********************
. STACK 500
; ************* Data Section **********************
. DATA
PSP_SEG DW 0
No_cl_mess db "This routine requires that a"
DB ' filename is on the command ' for printing.
DB 0dh,0ah, "Please try with a filename.", 0dh,0ah, "$"
File_bad_open db "Bad File Open", 0dh,0ah, "$"
File_bad_read db "Bad file read", 0dh,0ah, "$"
Printer_bad_mess DB "!! Printer Error!!!! ", 0DH,0AH," $ "
Printing_mess db "A file is being printed,", 0dh,0ah
DB "To stop printing, press ESC key", 0dh,0ah, "$"
FileName DB 128 dup (0)
File_handle DW 0
File_count DW 0
File_pointer DW Offset File_buffer
File_buffer DB 1024 dup (0)
; ************* ----------- *********************
; ************* Code Section *******************
. CODE
Start proc near
;D s and ES are indexing PSP area
mov al,[ds:80h]; load al with size: Data line
MOV dx, @data; Get segment address to data area
mov ds,dx;p oint DS to Data area
MOV psp_seg,es; save PSP Address
CMP al,1;?? Data in DOS command line??
JA get_psp_filename; branch if data found
; If here, there are no data on command line
;d isplay error message to user and terminate
Lea Dx,no_cl_mess
;-------------------------
Terminate_display:
;D isplay message Indexed by DX then terminate
MOV ah,09
int 21H;D OS call
;-------------------------
Terminate_program:
; Terminating the program
MOV ah,4ch set AH for terminating function
mov al,00; set terminating code variable
int 21H; call DOS to terminate
;------------------------------------------
; %%%%%%%%%%%%% ----------- %%%%%%%%%%%%%%%
Get_psp_filename:
; move PSP filename to filename-buffer in We data area
MOV Ax,ds
mov es,ax;p oint es to data segment
MOV ds,psp_seg
mov si,82h si source is PSP data area
Lea Di,filename
CLD; make strings go forward
Get_psp_data_1:
LODSB Load String Data byte
; Check for end of filename
CMP al,21h
; branch if end of string
JB Got_psp_filename
STOSB Store String Data byte
JMP get_psp_data_1
Got_psp_filename:
MOV al,0
STOSB make Asciiz string with zero end
Push ES
Pop ds; Reset data segment pointer
; Try to open file
MOV AH,3DH
Lea Dx,filename
MOV al,0 Read access code
int 21H;D OS call
Jnc FILE_OPEN_OK
Lea Dx,file_bad_open
JMP Terminate_display
;+++++++++++++++++++++++++++++++++++++++++++
;############### +++++++++++ ###############
FILE_OPEN_OK:
; Save file handle
MOV File_handle,ax
Lea dx,printing_mess;d isplay Start message
MOV ah,09
int 21H;D OS call
File_read:
; Read in block of file data
MOV ah,3fh
Lea Dx,file_buffer
MOV cx,1024
MOV Bx,file_handle
int 21H;D OS call
JNC FILE_READ_OK Branch if good read
; Else read file error occurred
; Close File
MOV Ah,3eh
MOV Bx,file_handle
int 21H
; Index exit error message
Lea Dx,file_bad_read
JMP Terminate_display
FILE_READ_OK:
; Check to the If no more file data
CMP ax,0
Je close_file branch if no data left
; Else reset data block size and pointer
MOV File_count,ax
Lea Bx,file_buffer
MOV file_pointer,bx
;!!!!!!!!!!!!!!!!! ^^ ^^ ^^ ^^!!!!!!!!!!!!!!!!!!!!
Print_data_block:
; main loop to print block of file data
; scan keyboard to check for the any keys
MOV ah,1
int 16H
JZ print_data_block_1; branch if no key
; Get key code out of buffer
MOV ah,0
int 16H; Call BIOS keyboard
CMP al,01bh Check Key code
Je close_file; branch if ESC
Print_data_block_1:
MOV Si,file_pointer
MOV Al,[si]
MOV ah,0
MOV dx,0 select LPT1
int 17H; BIOS Call
Test ah,25h
JNZ printer_error
Inc si
MOV File_pointer,si
Dec file_count
JNZ print_data_block; loop if more data
; else go read in next block of file data
JMP File_read
;!!!!!!!!!!!!!!!! ^^ ^^ ^^ ^^!!!!!!!!!!!!!!!!!!!!
Close_file:
MOV Ah,3eh
MOV Bx,file_handle
int 21H;D OS call
JMP Terminate_program
;--------------　?????????? -------------------
Printer_error:
; Index exit error message
Lea Dx,printer_bad_mess
JMP Terminate_display
;_______________________________________________
Start ENDP end of Start procedure
End start;d efine start as beginning of