Backing Up Files to more than 1 disk

[Keith E. Black]

How do I get powerbasic to back up files to more than one disk, if the first disk is full?
I wrote this code:
shell "copy class.txt a:\"
The size of class.txt is 1.57 mbytes.
The computer responds with disk full.
"How do I get it to ask me to insert another disk to complete
the copy process?
Thanks,
Keith

[Ian Cairns]

Since your file exceeds the size of a single floppy, you have to break it into smaller chunks. You can use pkzip with its disk spanning function, or do it yourself programmatically.

These are 2 programs I wrote a while ago to do this.

' To Span:
'***********
SPAN.BAS
$STRING 32  ' 32750 bytes
$COMPILE EXE
$INCLUDE "PB32.INC"  ' use PB32 library

IF ArgC(COMMAND$) < 3 THEN
  CALL Usage
END IF
tDrive$ = ArgV$(1, COMMAND$)
IF LEN(tDrive$)<2 THEN tDrive$ = tDrive$ + ":"
inFile$ = ArgV$(2, COMMAND$)
outFile$ = ArgV$(3, COMMAND$)
IF LEN(DIR$(inFile$))< 1 THEN
  PRINT "Input File Name does not exist!"
  CALL Usage
END IF

temp = INSTR(outFile$,".")
IF temp = 1 THEN CALL Usage
IF temp > 1 THEN outFile$ = LEFT$(outFile$,temp-1)
outFile$ = LEFT$(outFile$,8)

ON ERROR GOTO ErrorHandler
ihandle? = FREEFILE
OPEN inFile$ FOR BINARY AS ihandle?
inLen& = LOF(ihandle?)
ncount% = 1
tFile$ = tDrive$ + outFile$ + ".s01"
ohandle? = FREEFILE
OPEN tFile$ FOR BINARY AS ohandle?
freeSpc??? = DISKFREE(LEFT$(tDrive$, 1))
inbytes& = MIN(32256, inLen&, freeSpc???)
DO
  GET$ ihandle?,inbytes&, buffer$
  DECR inLen&, inbytes&
  PUT$ ohandle?, buffer$
  DECR freeSpc???, inbytes&  ' Keep track of space available on drive
  inbytes& = MIN(32256, inLen&)
  IF freeSpc??? < inbytes& THEN
    CLOSE # ohandle?  ' first close file on disk
' Prompt to insert disk
    CLS
    PRINT " Current Disk Full!"
    PRINT
    PRINT " Insert New Disk"
    PRINT
    PRINT " press any key to continue."
    WHILE INSTAT
      i$ = inkey$
    WEND  ' empty keyboard buffer
    WHILE NOT INSTAT : WEND
    CLS

    INCR ncount%, 1
    temp$ = LTRIM$(STR$(ncount%))
    IF LEN(temp$) < 2 THEN temp$ = "0" + temp$
    tFile$ = tDrive$ + outFile$ + ".s" + temp$
    OPEN tFile$ FOR BINARY AS ohandle?
    freeSpc??? = DISKFREE(LEFT$(tDrive$, 1))
    inbytes& = MIN(32256, inLen&, freeSpc???)
  END IF

  IF inbytes& < 1 THEN EXIT LOOP
LOOP

PRINT "Finished!"
CLOSE
END

ErrorHandler:
  CLOSE
  PRINT "Drive Not Ready!"
  END

SUB Usage
  PRINT
  PRINT "  Usage: Span <drive> <inputName> <outputName>"
  PRINT "Example: Span A: info.dat spanfile"
  PRINT "   Note: Span will automatically assign the extension"
  PRINT "         .s01, .s02, etc. to the output file name."
  END
END SUB       
'******

and to unSPAN:

'*****
'UNSPAN.BAS
'  
$STRING 32  ' 32750 bytes
$COMPILE EXE
$INCLUDE "PB32.INC"  ' use PB32 library

IF ArgC(COMMAND$) < 2 THEN
  CALL Usage
END IF
tDrive$ = ArgV$(1, COMMAND$)
IF LEN(tDrive$)<2 THEN tDrive$ = tDrive$ + ":"
outFile$ = ArgV$(2, COMMAND$)

ON ERROR GOTO ErrorHandler
inFile$ = DIR$(tDrive$ + "*.s01")
IF LEN(inFile$) < 1 THEN
  PRINT
  PRINT " No Span File to UnSpan!"
  END
END IF

inFile$ = LEFT$(inFile$, INSTR(inFile$,".")-1)
tFile$ = tDrive$ + inFile$ + ".s01"
ncount% = 1

ihandle? = FREEFILE
OPEN tFile$ FOR BINARY AS ihandle?
inLen& = LOF(ihandle?)
inbytes& = MIN(32256, inLen&)

ohandle? = FREEFILE
OPEN outFile$ FOR BINARY AS ohandle?
DO
  GET$ ihandle?,inbytes&, buffer$
  DECR inLen&, inbytes&
  PUT$ ohandle?, buffer$
  inbytes& = MIN(32256, inLen&)
  IF inbytes& < 1 THEN
    CLOSE # ihandle?  ' first close file on disk
' Prompt to insert next disk
    CLS
    PRINT " Current File Read!"
    PRINT
    PRINT " Insert Next Disk"
    PRINT
    PRINT " Press Q to Finish, or"
    PRINT " press any key to continue."
    WHILE INSTAT
      i$ = inkey$
    WEND  ' empty keyboard buffer
    WHILE NOT INSTAT : WEND
    i$ = UCASE$(inkey$)
    IF i$ = "Q" THEN EXIT LOOP
    CLS

    INCR ncount%, 1
    temp$ = LTRIM$(STR$(ncount%))
    IF LEN(temp$) < 2 THEN temp$ = "0" + temp$
    tFile$ = tDrive$ + inFile$ + ".s" + temp$
    DO
      IF LEN(DIR$(tFile$)) THEN EXIT LOOP
      PRINT
      PRINT
      PRINT "Wrong Disk!  Input disk containing " + tFile$
      PRINT
      PRINT " Press Q to Finish, or"
      PRINT " press any key to continue."
      WHILE INSTAT
        i$ = inkey$
      WEND  ' empty keyboard buffer
      WHILE NOT INSTAT : WEND
      i$ = UCASE$(inkey$)
      IF i$ = "Q" THEN CLOSE : END
      CLS
    LOOP
    OPEN tFile$ FOR BINARY AS ihandle?
    inLen& = LOF(ihandle?)
    inbytes& = MIN(32256, inLen&)
  END IF

LOOP

PRINT "Finished!"
CLOSE
END

ErrorHandler:
  CLOSE
  PRINT "Drive Not Ready!"
  END

SUB Usage
  PRINT
  PRINT "  Usage: UnSpan <drive> <outputName>"
  PRINT "Example: UnSpan A: spanfile.exe"
  PRINT "   Note: UnSpan will automatically look for the first"
  PRINT "         file ending .s01 to determine the input file name."
  END
END SUB
'*****

Regards,

------------------
[email protected]

[Mike Doty]

ftp://ftp.pkware.com/PK250DOS.EXE

Backup with spanning using PkZip
Syntax: BAKUP C:\FOLDER
BAKUP.BAT 
pkzip -rP -&fv a:myfiles.zip %1\*.*
.....................................
REST.BAT
cd\
pkunzip -d a:myfiles.zip

------------------

[Mel Bishop]

If you would like to back up you files within the program and without shelling out to DOS, you might consider this code

function space.a&(drive) ' 0 = default, 1 = "A" 2 = "B" etc.
reg 1,&h3600
reg 4,drive
call interrupt &h21
t1 = reg(1) : if t1 < 0 then t1 = t1 + 65536
t2 = reg(2) : if t2 < 0 then t1 = t2 + 65536
t3 = reg(3) : if t3 < 0 then t3 = t3 + 65536
space.a& = t1 * t2 * t3
end function

This function will return the amount of available space on the target drive. You can then write your code to make the determination on how much data you can write to the drive.

This function can also be used to determine if a diskette is in the drive without crashing the program. If the AX (reg(1)) register is &hFFFF (decimal -1) you probably don't have a diskette in the drive.


------------------

[Tom Hanlin]

Although DOS limitations may prevent it in this case-- you might note that multiplying three integers may produce a number much larger than will fit into a LONG. I'd suggest redefining space.a& as a QUAD to avoid the potential for problems.

You might also want to avoid using periods in function names to avoid future compatibility issues, as it makes your function look like a reference to a user-defined type.

------------------
Tom Hanlin
PowerBASIC Staff

[Lance Edmonds]

Another note: instead of testing for negative values, just use BITS??() to convert the signed INTEGER value to an unsigned WORD before the calculation.

Here is the code I use:

function FreeSpace&&(Drive%) local public
        reg 4, Drive%
        reg 1, &H3600
        call interrupt &H21
        function = bits??(reg(2)) * bits??(reg(3)) * bits??(reg(1))
end function

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>