BxbAsm

[SteveA]

Would there be any free/reallocate involved?
I can't track it down but I believe Win7 is very fussy on free, maybe even to the point of an actual bug??
I did a number of searches but couldn't come up with a definitive answer.

Yes.
I spent all day yesterday trying to figure out exactly what is going on.
I spent a good amount of time single-stepping thru Ollydebug, monitoring the registers and memory locations.

When a crash occurs, it's never while in the bxbasm module, but, rather in the ntdll.dll module.
I have become quite familiar with the breaking point, but, don't know what the exact cause is.
I can see everything is fine and then all of a sudden, a call to "free" goes off to never-never land.
It's the same everytime. Quite interesting.

It isn't as tho I have the wrong instruction, a mov, a push, a pop, etc., out of place.
The bxbasm code is correct.

Steve

[SteveA]

Okay,
I think I have it figured out.
It turns out that when "clear" is called, it is attempting to "free" some pointers.

For instance, this statement:     FIELD #1, 4 AS A$, 4 AS B$, 8 AS C1$, 8 AS D$, 10 AS E$
sets up an I/O buffer and the string-var names point to segments within the buffer.

Example:
    OPEN "R", #1, "test.txt", 34
establishes that the buffer is 34 bytes in size.

And, this statement:
    FIELD #1, 4 AS A$, 4 AS B$, 8 AS C1$, 8 AS D$, 10 AS E$
divides the buffer into segments,
where:
A$ points to byte 0 in the buffer:    [aaaa..............................]
B$ points to bytes 4 in the buffer:   [....bbbb..........................]
C1$ points to bytes 8 in the buffer: [........cccccccc..................]
D$ points to bytes 16 in the buffer: [................dddddddd..........]
E$ points to bytes 24 in the buffer: [........................eeeeeeeeee]

Unfortunately, the buffer is malloc'd else where.
When "free" is called (via clear), Clear indiscriminately attempts to "free" individual segments of the buffer.
Which it can't do.
Huh!

Now, I need to develop a work-around.

Steve

[SteveA]

James,
Okay, I've got it figured out, (I think).
The solution was, to not "free" (clear) the strings associated with the I/O buffer, but, to simply zero them out when they are no longer needed.
This required inventing another keyword, but, I see no other way of doing it.
Since the keywords FIELD and LSET/RSET directly pertain to the buffer and associated string names, I figured it was going to either be UNFIELD or UNSET.
So I decided on UNSET.
Here is an example of it's usage:

Code: [Select]

    FIELD #1, 4 AS A$, 4 AS B$, 8 AS D$, 10 AS E$
        LSET A$ = MKI$(dz)
        LSET B$ = MKI$(cz%)
        LSET D$ = MKD$(az#)
        RSET E$ = w$
        PUT 1, rec
    CLOSE 1
    UNSET A$, B$, D$, E$
    CLEAR


UNSET must be used after CLOSE and prior to a CLEAR command.

Here is what that snippet of asm code looks like:

Code: [Select]

  mov  eax, 0
  call closeafile
  mov  A, 0 ; release string from I/O buffer
  mov  B, 0 ; release string from I/O buffer
  mov  D, 0 ; release string from I/O buffer
  mov  E, 0 ; release string from I/O buffer
; --------------------------------------------------
  call clear_allvars


I have attached the new sources and executable.

Thanks,
Steve

[John]

So I decided on UNSET.

undef might work as well.

[jcfuller]

Steve,
  Don't I also need the new (changed) library sources as it still fails with test48.


James

[jcfuller]

Never mind! tried it before my second cup
All is fine.

James

[SteveA]

Never mind! tried it before my second cup
All is fine.

Okay.

I'm getting ready to install Linux.
I do have some questions, maybe John and Air can weigh in on this too.

I'd like to setup minimal partitions (disk size) for more than one version of Linux.
I assume you can do that and select which OS you want to boot from.
I know you used to be able to do that with Windows: Win-95::Win-98::OS2.

I'd like to be able to test bxbasm on various popular versions.
I assume Ubuntu is a given.
What other flavors should I also consider ?
I don't need to set up a Linux server, at this time, so just basic OS's.

Thanks,
Steve

[jcfuller]

Steve,
  A lot of Ubuntu users are jumping ship because of the Unity interface. I switched (not because of Unity) to Linux Mint (12). I see there is a (13) out but I'm not sure at this juncture if I'll upgrade.

  Another alternative is VirtualBox. It's a lot easier to try different OS's. You can even install XP along with several different flavors of 'nix.

James

[jcfuller]

Steve,
Another plus for VirtualBox is you can set up drives that can be shared. Dual booting can be a real pain when you are developing an app for windows and Linux with no easy way to share code.
I don't dual boot anymore at all (well I don't have to with all the boxes I have). I do have one system with Win7 and Virtualbox which has several XP configs and 5 different Linux setups. All can share data with the main win7 system.

James

[AIR]

Steve,

As James mentioned, virtualization is the way to go here.  The three main reasons are:

1- You don't have to mess around with multi-boot/partitioning and associated headaches
2- You can have multiple virtual machines running simultaneously along with your core os (depending on system and resources)
3- Most valuable reason:  Snapshots.  You can take a snapshot of an OS before any changes, and revert easily if those changes mess things up.

Several years ago when I was working on porting Hotbasic to Linux, I used the Distrowatch site to determine which Linux distributions I should use to check the port against.  I continued that approach when I worked on the various BCX ports. 

As of this morning, the top 3 Linux distributions listed on Distrowatch are Mint, Ubuntu, and Fedora.  I would also recommend a Debian install, since it's the Grand-daddy of Ubuntu and the dozens of Ubuntu derivatives.

Two more things I should mention:  If you have a 64bit machine, you can virtualize both 32 and 64 bit Linux versions, which if you have the space I highly recommend because of the differences in library locations between the two.  Lastly, if space becomes a concern you can simply archive the virtual machines to external storage to clear up drive space.

A.

[SteveA]

As James mentioned, virtualization is the way to go here.

Thanks for your advice, James and Armando.

If you have a 64bit machine, you can virtualize both 32 and 64 bit Linux versions, which if you have the space I highly recommend because of the differences in library locations between the two. 
Lastly, if space becomes a concern you can simply archive the virtual machines to external storage to clear up drive space.

Okay, my machine is 64-bit and has a 500 GB drive, with only Win-7 installed.
So space is no major issue.
Let's say I want all three (or four) of those distros, (VM), how do I get started ?
What do I need to download ?

Yesterday, after reading an article, I downloaded "GParted-Live":
http://gparted.sourceforge.net/livecd.php

supposed to be a tool that helps linux-partition the drive.

I have links for Fedora, Ubuntu, Mint and Debian.

Steve

[SteveA]

undef might work as well.

Yes it would, but, I thought it might confuse people who have used 'undef' in other languages.
While deciding, I looked through my BASIC Reference Manual, searching for either a keyword that might fit or making sure I wasn't using  one that is already in use for some other purpose.

I'm still open to suggestion.
As far as I'm concerned, "UNSET" is only an expedient, waiting for something better.

[John]

Yes it would, but, I thought it might confuse people who have used 'undef' in other languages.

That's why they call it Traditional BASIC. 

[jcfuller]

Steve,
  You won't need any partitioning software if you choose VirtualBox.
First get and install VitrualBox. Take the time to really give the instructions a good read.
https://www.virtualbox.org/

Then go to Distrowatch ( http://distrowatch.com/ )and check out the Rankings.
I'm going to check out both new Linux Mint 13 versions.

A word of warning re 32/64. If you opt for 64 you will also have to find and install all the needed 32bit libraries. For now I think 32 bit is in order especially as all your jwasm code is 32bit. I don't know how well versed you are in 64asm??? or even if you intend to expand Bxbasm
to 64bit???

James

[SteveA]

You won't need any partitioning software if you choose VirtualBox.
First get and install VitrualBox. Take the time to really give the instructions a good read.
https://www.virtualbox.org/

Okay, good to know that.
Thanks for the links.
I was googling "linux VM" and stubled across a forum that mentioned VirtualBox.

Then go to Distrowatch ( http://distrowatch.com/ )and check out the Rankings.

Right.

If you opt for 64 you will also have to find and install all the needed 32bit libraries.
For now I think 32 bit is in order especially as all your jwasm code is 32bit.
I don't know how well versed you are in 64asm??? or even if you intend to expand Bxbasm to 64bit???

Yeh, for the immediate, I will work with 32 bit.
I'm not ready for 64 bit asm.
I will work on that after we have a working 32 bit version running.
"Skin one cat at a time."

Thanks James,
Steve