Category : BASIC Source Code
Archive   : EMSFILES.ZIP
Filename : EMSFILES.BAS

' PROGRAM EMSFILES.BAS Written By Erik Olson, Spectra Tech Support
' ================================================================
' April 30, 1992 Spectra BBS (813) 625-1721
' Digitek BBS (813) 629-9145
' WELCOME TO THE MACHINE
' (813) 764-0165 login name "SPECTRA"
'
' This program uses the EMS functions of Thomas Hanlin's PBWIZ316.ZIP
' PowerBASIC library. This program reads two files:
' "\COMMAND.COM" and "\DOS\LIST.COM" and copies them into EMS memory.
'
' This first illustration reads LIST.COM with a single GET$, since it is
' a very small program (8-10k depending on the version) and slams it into
' a single 16K ems page.
'
' The second illustration reads COMMAND.COM in 16000 byte blocks (I was
' having some trouble with reading exactly 16K) and pushes them into
' 16K EMS pages. It reads COMMAND.COM in such a way that a file of
' any length could be read, as long as you have enough free EMS. This
' technique is preferred to the first, which would choke on a file larger
' than 16K.
'
' The final part of this program goes back into EMS and pulls out LIST.COM
' and COMMAND.COM and writes the files LIST2.COM and COMMAND2.COM to the
' current directory. These files are intact and actually work. (GEE!)
'
' Of course, this program serves no real purpose other than to demostrate
' the use of Hanlin's EMS functions. ...But you can see the potential for
' creating your own EMS string-swapping, FAST LOADING SHELLS, huge
' simulated arrays, complex help screens that don't kill your free string
' space, simulated "ram disk" type storage for software level processing...
' jeepers, thanks Tom!



$INCLUDE "PBWIZ.INC" '\
' > You have to have or download PBWIZ316.ZIP
$link "ems.obj" '/

On Error Goto ErrorHandler

IF EMSexists% THEN PRINT "EMS Exists..." ELSE PRINT "Sorry, no EMS found!":END

PRINT "Total EMS Memory:"; EMStotal%; " 16K pages"
PRINT " Total EMS Free:"; EMSfree%; " 16K pages"


' Allocate all free EMS

Pages%=EMSfree%
CALL EMSopen(Pages%, Handle%, ErrCode%)

' Map a 16K EMS blocks into the 64k EMS segment (a peekable pokeable area)

CALL EMSmap(Handle%, 0,0)


' Read a program file from disk - assuming LIST.COM is in the DOS directory
PRINT "Reading \DOS\LIST.COM..."
OPEN "\DOS\LIST.COM" FOR BINARY AS #1
GET$ 1,LOF(1), TEMP$
CLOSE #1

' put the file into EMS
PRINT " Putting it into EMS..."
DEF SEG = EMSseg&
POKE$ 0, TEMP$ + "SAVE THE KRILL!" ' an unlikely terminator

' Read another program from disk
PRINT "Reading \COMMAND.COM..."
OPEN "\COMMAND.COM" FOR BINARY AS #1

Physical% = 0 ' we're just using EMS block page 0, 16k at a time
Virtual% = 0 ' we need to map real EMS memory in 16k pages
blocks% = LOF(1) \ 16000
Remainder = LOF(1) - (LOF(1) \ 16000)

PRINT " Putting it into EMS..."
FOR y=1 to blocks%

Virtual% = Virtual% + 1 ' this is real EMS memory
CALL EMSmap(Handle%, Physical%, Virtual%)
GET$ 1, 16000, TEMP$
DEF SEG = EMSseg&
POKE$ 0, TEMP$
DEF SEG
next y

' get the rest of command.com
GET$ 1, Remainder, TEMP$
Virtual% = Virtual% + 1
CALL EMSmap(Handle%, Physical%, Virtual%)
DEF SEG = EMSseg&
POKE$ 0, TEMP$ + "SAVE THE KRILL!" ' so we know where COMMAND.COM
' ends in memory
DEF SEG
CLOSE #1


' we put LIST.COM and COMMAND.COM into EMS
' we will scan EMS memory and pull them out


' get LIST.COM back
PRINT:PRINT:PRINT "Writing LIST2.COM..."
CALL EMSmap(Handle%, 0,0)
DEF SEG = EMSseg&
TEMP$=PEEK$(0, 16000) ' Get the whole 16000 chars
DEF SEG
A% = INSTR(TEMP$, "SAVE THE KRILL!") - 1 ' locate our unlikely terminator
OPEN "O", #1, "LIST2.COM"
PRINT #1, LEFT$(TEMP$, A%);
CLOSE #1

' get COMMAND.COM back
Virtual%=0
PRINT "Writing COMMAND2.COM..."
OPEN "COMMAND2.COM" FOR OUTPUT AS #1
DO
Virtual%=Virtual%+1
CALL EMSmap(Handle%, 0, Virtual%)
DEF SEG = EMSseg&
TEMP$=PEEK$(0, 16000) ' 16000 bytes total: 0-16000
DEF SEG
Done% = INSTR(TEMP$, "SAVE THE KRILL!") ' find our unlikely terminator
IF Done% THEN EXIT LOOP
PRINT #1, TEMP$;
LOOP


' write the remainder of COMMAND2.COM
PRINT #1, LEFT$(TEMP$, Done%-1);
CLOSE #1
PRINT "Success!"
GOTO EndProg


ErrorHandler:
Er=Err
PRINT "Error:";Er ' big WHOOP, but we MUST make sure that EMSClose gets
Resume Here ' called before the program ends.
Here:



EndProg:
' MAKE SURE YOU DEALLOCATE EMS BEFORE QUITTING
' (so that's why.... Oh, never mind)

CALL EMSClose(Handle%)
END