Simtel MSDOS - Coast to Coast/simteldosarchivecoasttocoast2.iso/asmutil/asmlib37.zip/DISK.DOC

Text File | 1993-04-14 | 26KB | 891 lines

***************************** DISK & FILE *******************************

ASMLIB disk & file subroutines (C) Copyright 1992 - 1993 Douglas Herr
All rights reserved

The MS-DOS file attribute byte tells you whether a file is read-only,
system, a subdirectory, or may provide other information.  File attribute
bits may be combined.  Each bit of the file attribute means:

        0 = normal files
        1 = read-only
        2 = hidden files
        4 = system files
        8 = volume label (only one per disk)
       16 = subdirectories
       32 = archive bit set

   Thus a file with an attribute of 18 is a hidden subdirectory (16 OR 2)



                      ASMLIB buffered file I/O system

    Several ASMLIB subroutines are available for buffered file Input or
    Output.  Files to be managed by the buffered I/O system must be opened
    by FOPEN or FCREATE, and must be closed by FCLOSE.  Buffered file I/O
    will be much faster than unbuffered.  ASMLIB's default buffer size is
    4096 bytes; this can be changed by altering FBUFFER_SIZE in FOPEN.ASM
    and re-assembling.  Up to 20 files can be managed by FOPEN; this can
    be changed by altering NUMBER_OF_FILES in $handle.asm and reassembling.
    All ASMLIB file buffer subroutines assume DS:@data.

    To use the ASMLIB buffered I/O system excess DOS memory must be
    released.  See ENDPROG in SYSTEM.DOC.

    Subroutines: FOPEN        open file & initialize buffer
                 FCREATE      create file & initialize buffer
                 FCLOSE       flush & close output buffer; close file
                 FSEEK        move file pointer & update buffer
                 FGETSTR      read a string from buffer
                 FGETCHR      read a character from buffer
                 FGET         read specified number of bytes from buffer
                 FPUTSTR      write string to buffer
                 FPUTCRLF     write CR+LF to buffer
                 FPUTCHR      write character to buffer
                 FPUT         write specified number of bytes to buffer


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DISKFREE:    determines free disk space
Source:      diskfree.asm

Call with:   DL = drive number (drive A: = 0, default drive = -1)
Returns:     if CF = 0, DX:AX = free disk space
             if CF = 1, AX = DOS error code
              DiskFree does not trap "drive not ready" errors
Uses:        DX, AX, flags
Supports:    all DOS drives
Example:

include asm.inc
public  example_code

.code
example_code   proc
        mov    dl,0
        call    diskfree
        jc      disk_error


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DISKWP:      determines if a floppy disk is write-protected
Source:      diskwp.asm

Call with:   DL = floppy disk number (drive A: = 0)
Returns:     AL = BIOS error code
                0 = no error
                1 = invalid disk number
                3 = disk is write-protected
              128 = drive not ready
Uses:        AX, flags
Supports:    physical drives A: and B:
Example:

include asm.inc

public  mycode
extrn   diskwp:proc

.code
diskwp  proc
        .
        .
        .
        mov     dl,1        ; drive B:
        call    diskwp      ; can I write to this disk?
        or      al,al
        jz      no_problem


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DOTBAK:      changes the file extension of an existing file to .BAK
Source:      dotbak.asm (strrchr.asm)

Call with:   DS:[SI] = address of a ASCIIZ valid filename
             assumes DS:@data
             dotbak deletes a previous .BAK file of this name and
             renames the input filename.ext to filename.bak.
Returns:     if CF = 0, no error
             if CF = 1, AL = DOS error code.  If AL = 5, the previous
             .BAK filename is probably read-only.  All other errors refer
             to the name change operation.
Uses:        AX, flags
Example:

extrn  dotbak:proc

.data

disk_doc  db 'DISK.DOC',0

.code
; program fragment assumes DS:@data
             .
             .
             .
             mov   si,offset DGROUP:disk_doc
             call  dotbak


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FCLOSE:      close a file managed by ASMLIB's buffered file I/O system
Source:      fopen.asm ($handle.asm, dosalloc.asm)

Call with:   BX = file handle
             The file must have been opened by FOPEN or FCREATE;  If the
             file is not read-only, the output buffer will be written to
             the disk file before closing the file.
Returns:     if CF = 0, no error
             if CF = 1, AX = error code
Uses:        AX, flags
Example:     see FOPEN




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FCOPY:       copy a file
FCOPYM:      copy a file using supplied memory buffer
Source:      fcopy.asm

Call with:   DS:[SI] = address of source filename
             ES:[DI] = address of destination filename
             Both filenames must be ASCIIZ strings.  Drive and path need
             not be fully specified; filenames may not include * or ?
             wildcards.
             FCOPY only: Requires 64k DOS memory available
             FCOPYM only: AX = segment address of 64k buffer
Returns:     if CF = 0, no problem
             if CF = 1, AX = DOS error code (AX = -1 if insufficient memory)
Uses:        AX, CF
Example:

.data
        db 'b:'
source  db 'asmlib.lib',0         ; copy the library to b:

extrn   fcopy:proc
.code
; program fragment assumes DS:@data
        .
        .
        push    ds
        pop     es
        assume es:@data
        lea     si,source
        mov     di,si                ; DI also points to source
        sub     di,2                 ; back the pointer to the 'B:'
        call    fcopy
        jc      oops



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FCOUNT:      counts the number of files matching an ASCIIZ filespec string.
             The filespec string may include the '*' and '?' wildcards.
Source:      fcount.asm

Call with:   DS:[DX] pointing to filespec string
             CX = file attributes
             assumes DS:@data
Returns:     AX = number of files matching the filespec string
Uses:        AX, all other registers and flags are saved
Example:

.code
; program fragment assumes DS:@data
        .
        .
        .
        lea    dx,filespec      ; address of filespec string
        xor    cx,cx            ; normal files only
        call   fcount


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FCREATE:     create new file and initialize output buffer
Source:      fcreate.asm ($handle.asm, dosalloc.asm)

Call with:   DS:[DX] pointing to ASCIIZ filename
             The file is created with write-only access.  If a file with
             the same name already exists, it is truncated to zero
             length by FCREATE.
Returns:     if CF = 0, AX = file handle
             if CF = 1, AX = error code
Uses:        AX, flags
Example:

include  asm.inc

public   myprog
extrn    fcreate:proc

.data
file_name   db 'ANYNEW.FIL',0
file_handle dw 0

.code
myprog   proc
; program fragment assumes DS:@data
         .
         .
         .
         lea   dx,file_name
         call  fcreate
         jc    something_went_wrong
         mov   file_handle,ax ; save the handle
         .
         .
         .


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FEXIST:      determines if a file exists and can be opened with read access
Source:      fexist.asm

Call with:   DS:[DX] pointing to ASCIIZ filename
Returns:     if CF = 0, file exists
             if CF = 1, AX = MS-DOS error code
Uses:        AX, CF; all other flags and registers are saved
Example:

include  asm.inc

extrn    fexist:proc
.data
filename db 'asmlib.doc',0

.code
; program fragment assumes DS:@data
         .
         .
         .
         lea   dx,filename
         call  fexist
         jnc   got_the_file      ; if CF = 0, go on
         jmp   doserror          ; else go to error handling code



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FFLUSH:      flushes the ASMLIB and DOS output buffers for specified handle
Source:      fflush.asm (fseek.asm, $handle.asm)

Call with:   BX = file handle
             flushing the buffers guards against data loss in case of system
             failure, such as power loss
Returns:     if CF = 0, no error; function successful
             if CF = 1, AX = DOS error code
Uses:        AX, flags
Example:

include asm.inc

extrn fflush:proc

.code
; program opens file & writes to file
      .
      .
      .
; flush the buffers to disk
      mov    bx,handle
      call   fflush



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FGET:        read specified number of bytes from file buffer
Source:      fget.asm ($handle.asm, $fget.asm)

Call with:   BX = file handle
             CX = number of bytes requested (up to 4096 bytes)
Returns:     if CF = 0, AX = number of bytes read
                        ES:[BX] points to data in buffer
             if CF = 1, AX = DOS error code
Uses:        AX, BX, ES, flags
Example:

include   asm.inc

extrn     fopen:proc, fget:proc

.data
file_name   db 'asmlib.doc',0
file_handle dw 0

.code
; program fragment assumes DS:@data
          .
          .
          .
          lea   dx,file_name
          call  fopen
          jc    fopen_problem
          mov   file_handle,ax  ; save for later

          mov   bx,ax           ; file handle
          mov   cx,8            ; I want 8 bytes
          call  fget            ;  returned at ES:[BX]
          jc    read_problem    ; uh oh, trouble ...
          cmp   ax,cx           ; did I get what I wanted?
          jne   not_enough
          .
          .




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FGETCHR:     read a character from a file buffer
Source:      fgetchr.asm ($handle.asm)

Call with:   BX = file handle
Returns:     if CF = 0, AL = next character from file buffer
             if CF = 1, AX = DOS error code
                        AX = 0 if at end of file
Uses:        AX, flags
Example:

include   asm.inc

extrn     fopen:proc, fgetchr:proc

.data
file_name   db 'asmlib.doc',0
file_handle dw 0

.code
; program fragment assumes DS:@data
          .
          .
          .
          lea   dx,file_name
          call  fopen
          jc    fopen_problem
          mov   file_handle,ax  ; save for later

          mov   bx,ax           ; file handle
          call  fgetchr         ; character in AL
          jc    read_problem

          .
          .



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FGETSTR:     read an ASCII string from a file buffer
Source:      fgetstr.asm ($handle.asm, $fget.asm)

Call with:   BX = file handle
             ASCII strings may be terminated with either 0Dh or 0Dh+0Ah.
             After reading each string, FGetStr positions the buffer pointer
             to read the next string.  String length should be less than
             the buffer size.  See FOPEN.
Returns:     if CF = 0, ES:[BX] points to string in buffer
                        CX = length of ASCII string
                     if CX = byte length of buffer, string >= size of buffer
             if CF = 1, AX = DOS error code
                        AX = 0 if end of file
Uses:        ES, BX, AX, CX, flags
Example:

include   asm.inc

extrn     fopen:proc, fgetstr:proc

.data
file_name   db 'asmlib.doc',0
file_handle dw 0

.code
; program fragment assumes DS:@data
          .
          .
          .
          lea   dx,file_name
          call  fopen
          jc    fopen_problem
          mov   file_handle,ax  ; save for later

          mov   bx,ax           ; file handle
          call  fgetstr
          jc    read_problem

          call  strndup         ; make a copy in near heap for later
          .
          .
          .



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FILELIST:    creates a list of file names matching a filespec mask
Source:      filelist.asm (fcount.asm, dosalloc.asm)

Call with:   DS:[SI] pointing to filespec mask
             CX = file attribute mask
Returns:     if CF = 0:
               ES = base segment address of list buffer
               AX = number of filenames in list
               CX = list field width
             if CF = 1, AX = MS-DOS error code
             You should use DOS function 49h to release the file list
             buffer when you're done with it.
Uses:        AX, CX, ES, CF
Example:

include asm.inc

public  myproc

.data
filespec db '*.*',0

.code
; program fragment assumes DS:@data
        .
        .
        .
        lea    si,filespec
        mov    cx,16            ; normal files and subdirectories
        call   filelist
        jc     cant_do_it       ; oops



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FINDDATE:    given a successful call to FindFirst or FindNext, returns
             the file's date stamp
Source:      findfile.asm

Call with:   DS:[BX] pointing to DTA buffer; assumes DS  @DATA
Returns:     DX = month
             AX = day
             CX = year
Uses:        AX, CX, DX, flags
Example:

.code
; program fragment assumes DS:@data
        .
        .
        .
        lea    bx,filespec
        mov    cx,0              ; normal files only
        call   findfirst         ; find first matching file
        jc     no_more_files
        cmp    ax,-1
        je     no_more_files
        call   finddate



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FINDFIRST:   This subroutine, when used with FindNext, finds files on
             a disk which match an ASCIIZ filespec string.  The filespec
             string may contain the '*' and '?' wildcards.
Source:      findfile.asm (heap.asm)

Call with:   DS:[BX] pointing to ASCIIZ filespec string; assumes DS:@data
             CX = file attribute mask

             FindFirst allocates space for a local DTA buffer from the
             near heap.  See FindNext; also see HINIT.

Returns:     AX = error code
             -1 = insufficient memory in near heap (128 bytes required)
             0 = no error
             CF = 1 if no files match the filespec string
             DS:[BX] -> DTA buffer if the subroutine is successful.  Do not
             alter the 128 bytes in the DTA buffer.
             The name of the file is an ASCIIZ string at 30[BX]
             The file attribute is a byte at 21[BX]
             The low word of the file's size is at 26[BX]
             The high word of the file's size is at 28[BX]
Uses:        AX, BX, flags
Example:

.code
; program fragment assumes DS:@data
     .
     .
     .
     lea    bx,filespec
     mov    cx,0              ; normal files only
     call   findfirst         ; find first matching file
     jc     no_more_files
     cmp    ax,-1
     je     no_memory         ; memory not available

; print the filename on the screen
tprint_next:
     mov    si,bx
     add    si,30             ; point to filename in DTA buffer
     mov    dh,count          ; row value
     mov    dl,0              ; column 0
     mov    ah,12             ; color attribute - RED!
     call   tprint            ; display the file name on the screen
     inc    count             ; next filename on next row
     call   findnext          ; any more matching filenames?
     jnc    tprint_next
no_more_files:

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FINDNEXT:    finds file matching search string; use after FindFirst.
             used only after a successful call to FindFirst.
Source:      findfile.asm (heap.asm)

Call with:   no parameters; assumes DS:@data

             FindNext de-allocates the DTA buffer space after the first
             unsuccessful search for a matching file.

Returns:     DS:[BX] -> DTA buffer
             CF = 1 if no more files match the filespec string.
Uses:        BX, flags
Example:     see FindFirst.


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FINDTIME:    given a successful call to FindFirst or FindNext, returns
             the file's time stamp
Source:      findfile.asm

Call with:   DS:[BX] pointing to DTA buffer; assumes DS:@data
Returns:     DX = hour
             AX = minute
             CX = second
Uses:        AX, CX, DX, flags
Example:     lea    bx,filespec
             mov    cx,0              ; normal files only
             call   findfirst         ; find first matching file
             jc     no_more_files
             cmp    ax,-1
             je     no_more_files
             call   findtime



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FLOAD:       read a file into far memory
Source:      fload.asm (fsize.asm, allocdos.asm)

Call with:   DS:[DX] pointing to ASCIIZ filename
Returns:     if CF = 0, BX = initial segment address of memory block
                        DX:AX = bytes loaded from disk
             if CF = 1, AX = DOS error code
Uses:        AX, BX, DX, CF
Example:

include asm.inc

public  test_fload

extrn   fload:proc

.data
fileseg         dw 0
fname           db 'filename.txt',0
file_size       dw 0,0

.code
test_fload      proc
; program fragment assumes DS:@data
        .
        .

        lea     dx,fname
        call    fload           ; read file into DOS memory
        jc      no_good         ;  jump if there was a problem

        mov     fileseg,bx      ; save initial segment address
                                ; of allocated memory
        mov     file_size,ax    ; save file size
        mov     file_size+2,dx

no_good:                        ; return with CF = 1 if error
        ret                     ; CF = 0 if no error
test_fload      endp
        end



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FOPEN:       opens existing file and initializes ASMLIB buffered I/O
Source:      fopen.asm (dosalloc.asm, $handle.asm)

Call with:   DS:[DX] pointing to name of file to be opened
             AL = access mode
              0 = read-only access
              1 = write-only access
              2 = read-write access NOT SUPPORTED YET
Returns:     if CF = 0, AX = file handle
             if CF = 1, AX = ASMLIB or DOS error code; file not opened
                if AX = 0, insufficient DOS memory available
                if AX = 0FFFFh, no handles available in ASMLIB I/O array;
                   change NUMBER_OF_HANDLES in $handle.asm amd re-assemble
                   (default = 20 handles)
Uses:        AX, flags
Example:

include  asm.inc

public   myprog
extrn    fopen:proc, fclose:proc

.data
file_name   db 'ASMLIB.DOC',0
file_handle dw 0

.code
myprog   proc
; program fragment assumes DS:@data
         .
         .
         .
         lea   dx,file_name
         xor   al,al          ; read-only access
         call  fopen
         jc    something_went_wrong
         mov   file_handle,ax ; save the handle
         .
         .
         .

; all done with this file
         mov   bx,file_handle
         call  fclose



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FPUT:        write specified number of bytes to output file buffer
Source:      fput.asm ($handle.asm)

Call with:   BX = file handle
             ES:[DI] pointing to data to write
             CX = number of bytes to write
Returns:     if CF = 0, no error
             if CF = 1, AX = error code
Uses:        AX, flags
Example:

include  asm.inc

public   myproc
extrn    fput:proc
extrn    fputchr:proc
extrn    fputcrlf:proc

.data
data1    db 'several bytes may be written at once'
data_len equ $-data1

.code
; program fragment assumes DS:@data
         .
         .
         .
         mov   bx,output_handle
         push  ds
         pop   es                     ; ES = DS = DGROUP
         assume  es:DGROUP
         lea   di,data1               ; ES:[DI] -> data1
         mov   cx,data_len            ; bytes to write
         call  fput
         call  fputcrlf               ; write CR+LF for new line
                                      ; in ASCII text file
         mov   al,26                  ; End-of-File byte (optional)
         call  fputchr


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FPUTCHR:     write one character to output file buffer
Source:      fputchr.asm (fput.asm)

Call with:   BX = output file handle
             AL = character to write
Returns:     if CF = 1, AX = MS-DOS error code
             if CF = 0, no error
Uses:        AX, flags
Example:     see FPUT
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FPUTCRLF:    write CR+LF pair to output file buffer
Source:      fputcrlf.asm (fput.asm)

Call with:   BX = output file handle; file must have been opened by
             FOPEN or FCREATE
Returns:     if CF = 0, no error
             if CF = 1, AX = DOS error code
Uses:        AX, flags
Example:     see FPUT



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FPUTSTR:     write an ASCIIZ string to output buffer
Source:      fpustr.asm (strlen.asm, fput.asm)

Call with:   BX = file handle
             ES:[DI] points to ASCIIZ string
Returns:     if CF = 0, AX = bytes written
             if CF = 1, AX = DOS error code
Uses:        AX, flags
Example:

include  asm.inc

public   myproc
extrn    fputstr:proc
extrn    fputcrlf:proc

.data
strptr   dw 0                      ; pointer to string, assigned by program

.code
; program fragment assumes DS:@data
         .
         .
         .
         push  ds
         pop   es                     ; ES = DS = DGROUP
         assume  es:DGROUP
         mov   bx,output_handle
         mov   di,strptr              ; ES:[DI] -> data1
         call  fputstr
         call  fputcrlf               ; write CR+LF for new line
                                      ; in ASCII text file



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FSEEK:       move file pointer for a file opened by FOPEN
Source:      fseek.asm ($handle.asm)

Call with:   BX = file handle
             AL = method code: 0 = absolute offset from start of file
                               1 = signed offset from current file pointer
                               2 = signed offset from end of file
             CX:DX = dword offset
Returns:     if CF = 1, AX = DOS error code
             if CF = 0, DX:AX = current location of file pointer
Uses:        AX, DX, flags

Example:

include   asm.inc

public  whoknows

extrn fopen:proc, fseek:proc

.data
file0   db 'file0.dat',0

.code
whoknows  proc
; program fragment assumes DS:@data
        .
        .
        .
        mov     dx,offset DGROUP:file0
        mov     al,1              ; write only
        call    fopen
        jc      error
        xor     cx,cx
        mov     dx,cx             ; zero offset
        mov     al,2              ; relative to end of file
        call    fseek             ; move pointer to end of file





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FSIZE:       determines a file's size
Source:      fsize.asm

Call with:   BX = valid file handle
Returns:     if CF = 0, DX:AX = file size
             if CF = 1, AX = MS-DOS error code
Uses:        AX, DX, CF
Example:

include asm.inc

extrn   fsize:proc

.data
filenam db 'ASMLIB.DOC',0      ; ASCIIZ filename

.code
        .
        .
        .
        lea     dx,filenam     ; point to filename
        mov     ax,3D00h       ; MS-DOS open file function, read-only
        int     21h
        jc      oops           ; jump to error control
                               ; else no problem - continue
        mov     bx,ax          ; file handle in BX
        call    fsize


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QFNAME:      qualifies a filename
Source:      qfname.asm

Call with:   DS:[BX] pointing to a filename; the filename may contain
             drive specification and/or complete or partial path name.
             Drive specification and path name not required.
Returns:     DS:[SI] pointing to the full DRIVESPEC:\PATH\FILENAME
             CX = length of full filename
             Note that DS:[SI] points to QFName's buffer space; the next
             call to QFName will return a new filename at the same address.
Uses:        SI, CX, flags
Example:

include asm.inc

.data
docs   db '*.doc',0         ; search for .DOC files in current directory

.code
; program fragment assumes DS:@data
       .
       .
       .
       lea    bx,docs
       call   qfname