C to Java Byte Code

[Paul Lutus]

Re: C to Java Byte Code

Alex Fraser wrote:
[color=blue]
> "Paul Lutus" <nospam@nosite. zzz> wrote in message
> news:10nqmt2okb 8hnec@corp.supe rnews.com...
> [snip][color=green]
>> If the compiler is ANSI C compliant, my example program will compile on
>> that compiler and run on that plartform. Unions are supported by C, they
>> are not supported by Java, and they are not supported by the program
>> under discussion.[/color]
>
> From these statements, I infer that you have an example program which
> demonstrates that unions are not supported. Is this correct? And if so,
> what is this example program?[/color]

1. The OP, unhappy with the original thread and eager to get some additional
free publicity for his commercial product, created a new thread. The old
thread has the same name and starts here:

<a9083a87.04101 41937.1a7d4e1d@ posting.google. com>

2. Java does not support the mapping of one variable type onto another.

3. The product in question solves this problem by turning everything into a
32-bit word, this making the "union" issue moot, since there is no point
creating a union betweeen a thing and itself.

The basic issue is that the disparate data types that can be mapped using
"union" in C, cannot be mapped at all in Java (because of the latter's
strong data typing). The OP solved this problem by making all data into
32-bit words.
[color=blue]
>
> Do you have any other evidence on which you base the claim above?[/color]

Please take the time to read this and the prior thread before raising closed
issues.
[color=blue]
> And if
> so, what is it?[/color]

*sigh*

<cl7gbh$7th$1@h ood.uits.indian a.edu>

*************** *************** *************** *************** *******

"The size of each char, int, long, or float is 1 word (32 bits long).
So, sizeof(int) is 1, sizeof(char) is 1, sizeof(float) is also 1,
you got the idea.  Using a large array of int to mimic addressable memory is
the cause for this.  The indexes to this large array are treated as
addresses.  This memory is word-addressable and not byte-addressable.
And programs that assume a byte-addressable architecture will need to be
modified to suit the one used by MPC.  Unions are supported."

*************** *************** *************** *************** *******

If, as the OP claims, all data are 32-bit words, then the claim that unions
are supported is false, since (1) Java will not allow disparate data types
to be overlaid in memory, and (2) a union's purpose is the mapping of
disparate data types, and there aren't any disparate data types.

BTW there is also no support for anything that requires fewer or more than
32 bits, e.g no support for typical doubles as just one example.

--
Paul Lutus

http://www.arachnoid.com

[Paul Lutus]

Re: C to Java Byte Code

Dave Vandervies wrote:
[color=blue]
> In article <10nqq7cnnsv852 5@corp.supernew s.com>,
> Paul Lutus <nospam@nosite. zzz> wrote:[/color]

/ ...
[color=blue][color=green]
>>When you are ready to address the topic of this thread, post again.[/color]
>
> I'm attempting to address the suitability of using an array of 32-bit
> values to store values of varying types and use a union to convert
> between the values stored there.[/color]

That is not the topic, and you need to find out what "thread drift" refers
to. You are always free to start any thread, on any topic, in any suitable
newsgroup. For this thread, a thread originated and cross-posted to four
nearly unrelated newsgroups by an unscrupulous commercial vendor eager for
free publicity, you have limited options other than addressing the topic.
[color=blue]
> Since that's obviously not what you think the topic of this thread is,[/color]

I did not start this thread, cross-post it, or choose its topic.
[color=blue]
> there's not much point in me continuing.[/color]

There is not much point in your continuing.
[color=blue]
> This thread is going in the killfile as soon as I post this article.[/color]

Why not before?
[color=blue]
> This means you can claim I'm wrong,[/color]

Post the quote of the statement you falsely claim I made, or retract your
false claim. Never invent statements for other people. I never said what
you claim, the ball is in your court, we won't hold our breath.

grep "wrong" (this thread) || echo "No evidence, no argument."
[color=blue]
> accuse me of onanism, and refuse to
> accept that you might not know everything all you want,[/color]

"Everything all you want"? I was right, your brain really is offline.
[color=blue]
> and I promise
> not to reply unless somebody changes the subject line.[/color]

We'll see.

--
Paul Lutus

http://www.arachnoid.com

[Mohd Hanafiah Abdullah]

Re: C to Java Byte Code

In article <10nqamhfej8qqf 5@corp.supernew s.com>,
Paul Lutus <nospam@nosite. zzz> wrote:[color=blue]
>
>Since unions are not supported in the product being discussed, their
>ubiquity is not the issue, and your argument is just that, nothing more.
>Also, the only "union" supported in the product is to make two or more
>references to the same integer-sized variable (language provided by Mr.
>Abdullah). Therefore, in point of fact, the product cannot map two
>distinct, same-size entities onto one another, which is what a "union"
>should be capable of doing. This means that Mr. Abdullah's claims in this
>specific regard are, like so many others, not correct.[/color]

Excuse me, but unions are supported in the product being discussed.

Napi
--

http://www.cs.indiana.edu/hyplan/napi.html

[Mohd Hanafiah Abdullah]

Re: C to Java Byte Code

In article <10nqefd36j5pod 2@corp.supernew s.com>,
Paul Lutus <nospam@nosite. zzz> wrote:[color=blue]
>Dave Vandervies wrote:
>[color=green]
>> In article <10nqamhfej8qqf 5@corp.supernew s.com>,
>> Paul Lutus <nospam@nosite. zzz> wrote:[color=darkred]
>>>Gerry Quinn wrote:[/color]
>>[color=darkred]
>>>> As I understand it, this issue only affects incompetent programmers who
>>>> write code that assumes that bytes have eight bits.
>>>
>>>No, the original prohibition to which I refer was provided by Mr.
>>>Abdullah, who said:
>>>
>>><cl7gbh$7th$ 1@hood.uits.ind iana.edu>
>>>
>>>************ *************** *************** ***********
>>>
>>>" ... programs that assume a byte-addressable architecture will need to be
>>>modified to suit the one used by MPC."
>>>
>>>************ *************** *************** ***********
>>>
>>>Care to retract your argument now, or later?[/color]
>>
>> ...So it doesn't provide a byte-addressable memory model.
>>
>> Care to provide a reference to support your claim that C requires a
>> byte-addressable memory model?[/color]
>
>Before you try to shift the burden of evidence, care to find where I made
>this claim? Please do not drift the tread -- this is the easiest imaginable
>activity, but it sheds no light on anyting.
>[color=green][color=darkred]
>>>Since unions are not supported in the product being discussed, their
>>>ubiquity is not the issue, and your argument is just that, nothing more.
>>>Also, the only "union" supported in the product is to make two or more
>>>references to the same integer-sized variable (language provided by Mr.
>>>Abdullah). Therefore, in point of fact, the product cannot map two
>>>distinct, same-size entities onto one another, which is what a "union"
>>>should be capable of doing. This means that Mr. Abdullah's claims in this
>>>specific regard are, like so many others, not correct.[/color]
>>
>> I haven't been following this thread too closely, but if I'm not mistaken,
>> union support was never claimed to be this limited (except by you).[/color]
>
>The OP eventually admitted that all variables are mapped to Java native
>integers -- all of them. This means there is no support for the property of
>unions that they can conjoin two unrelated data types so long as their size
>is adjusted to be the same.[/color]

All variables are located in the large array of int. As a result of
register allocation several of the variables end up cached in Java native
variables of int type or float type. But, their home locations are always
in the large array of int. And again, unions and structs are supported.

Napi

--

http://www.cs.indiana.edu/hyplan/napi.html

[Mohd Hanafiah Abdullah]

Re: C to Java Byte Code

In article <10nqnnc7nau6m7 3@corp.supernew s.com>,
Paul Lutus <nospam@nosite. zzz> wrote:[color=blue]
>Dave Vandervies wrote:
>[color=green]
>> In article <10nqefd36j5pod 2@corp.supernew s.com>,
>> Paul Lutus <nospam@nosite. zzz> wrote:[color=darkred]
>>>Dave Vandervies wrote:[/color][/color]
>
>/ ...
>[color=green][color=darkred]
>>>> Care to provide a reference to support your claim that C requires a
>>>> byte-addressable memory model?
>>>
>>>Before you try to shift the burden of evidence, care to find where I made
>>>this claim? Please do not drift the tread -- this is the easiest
>>>imaginable activity, but it sheds no light on anyting.[/color]
>>[/color][/color]
....[color=blue][color=green]
>> It does NOT invalidate the claim that this is a C implementation targeting
>> the JVM, with runtime code that treats a large array of Java integers
>> as a word-addressable memory space.[/color]
>
>Ther OP made false claims both here and on his Web site. I said the claims
>were false. At which point did you lose track of the topic?[/color]

Actually neither I here nor the website ever claimed this is a conversion from
C to Java, but a conversion from C to Java Byte Code, and that's a big
difference. Please read carefully.

Napi

--

http://www.cs.indiana.edu/hyplan/napi.html

[Paul Lutus]

Re: C to Java Byte Code

Mohd Hanafiah Abdullah wrote:
[color=blue]
> In article <10nqamhfej8qqf 5@corp.supernew s.com>,
> Paul Lutus <nospam@nosite. zzz> wrote:[color=green]
>>
>>Since unions are not supported in the product being discussed, their
>>ubiquity is not the issue, and your argument is just that, nothing more.
>>Also, the only "union" supported in the product is to make two or more
>>references to the same integer-sized variable (language provided by Mr.
>>Abdullah). Therefore, in point of fact, the product cannot map two
>>distinct, same-size entities onto one another, which is what a "union"
>>should be capable of doing. This means that Mr. Abdullah's claims in this
>>specific regard are, like so many others, not correct.[/color]
>
> Excuse me, but unions are supported in the product being discussed.[/color]

Post the byte code in which a Java float is united with a Java integer. Or
retract your statement.

Unions are not supported in your product. A C union is a joining of two or
more distinct variable types with simultaneous access to both, e.g. it is
an example of a memory block shared between data types. This is not allowed
in Java because of strong typing.

You have arranged to create a single 32-bit word datatype to represent
everything, so there is no distinction between one kind of variable and
another. Therefore there are no disparate data types, therefore there are
no unions as that term is understood.

But, as I say above, prove me wrong. Post the Java bytecode that unites a
Java float and a Java integer in the same address space, something not
allowed in Java.

--
Paul Lutus

http://www.arachnoid.com

[Paul Lutus]

Re: C to Java Byte Code

Mohd Hanafiah Abdullah wrote:
[color=blue]
> In article <10nqefd36j5pod 2@corp.supernew s.com>,
> Paul Lutus <nospam@nosite. zzz> wrote:[/color]

/ ...
[color=blue][color=green]
>>The OP eventually admitted that all variables are mapped to Java native
>>integers -- all of them. This means there is no support for the property
>>of unions that they can conjoin two unrelated data types so long as their
>>size is adjusted to be the same.[/color]
>
> All variables are located in the large array of int. As a result of
> register allocation several of the variables end up cached in Java native
> variables of int type or float type.[/color]

Please explain how you have used "register allocation" to circumvent Java's
strong data typing. Or are you talking about native code called by Java?
[color=blue]
> But, their home locations are always
> in the large array of int. And again, unions and structs are supported.[/color]

Show us the bytecode that overlays a Java float and a Java integer into the
same memory space. That is what a union is. Show us the Java bytecode that
allows one to manipulate individual bits of a Java float datatype, as a C
union allows.

If you use the obvious approach of translating the float using
Float.floatToIn tBits() and the reverse method, it wil be interesting to se
how you handle simultanous changes to both forms. In any case, it is not a
union. Java doesn't allow this.

--
Paul Lutus

http://www.arachnoid.com

[Paul Lutus]

Re: C to Java Byte Code

Mohd Hanafiah Abdullah wrote:
[color=blue]
> In article <10nqnnc7nau6m7 3@corp.supernew s.com>,
> Paul Lutus <nospam@nosite. zzz> wrote:[/color]

/ ...
[color=blue][color=green]
>>Ther OP made false claims both here and on his Web site. I said the claims
>>were false. At which point did you lose track of the topic?[/color]
>
> Actually neither I here nor the website ever claimed this is a conversion
> from C to Java, but a conversion from C to Java Byte Code, and that's a
> big difference.[/color]

No, it is not a difference at all. This is because of "javap" and similar
tools, which allow one to acquire a rudimentary source file from any Java
bytecode file.

Or are you claiming that you have created Java bytecode that cannot be
rendered into human-readable form by "javap" and other similar tools? I am
sure Sun Microsystems will be very interested to hear of this development.
[color=blue]
> Please read carefully.[/color]

Please check your facts before posting. In any case, as anyone can see by
reading this and the thread you abandoned, the objections are not about
whether Java source or bytecode is generated, but whether the statements
made are valid claims or marketing hype.

--
Paul Lutus

http://www.arachnoid.com

[Mohd Hanafiah Abdullah]

Re: C to Java Byte Code

In article <10nre1ja02ulld c@corp.supernew s.com>,
Paul Lutus <nospam@nosite. zzz> wrote:[color=blue]
>Mohd Hanafiah Abdullah wrote:
>[color=green]
>> In article <10nqamhfej8qqf 5@corp.supernew s.com>,
>> Paul Lutus <nospam@nosite. zzz> wrote:[color=darkred]
>>>
>>>Since unions are not supported in the product being discussed, their
>>>ubiquity is not the issue, and your argument is just that, nothing more.
>>>Also, the only "union" supported in the product is to make two or more
>>>references to the same integer-sized variable (language provided by Mr.
>>>Abdullah). Therefore, in point of fact, the product cannot map two
>>>distinct, same-size entities onto one another, which is what a "union"
>>>should be capable of doing. This means that Mr. Abdullah's claims in this
>>>specific regard are, like so many others, not correct.[/color]
>>
>> Excuse me, but unions are supported in the product being discussed.[/color]
>
>Post the byte code in which a Java float is united with a Java integer. Or
>retract your statement.
>
>Unions are not supported in your product. A C union is a joining of two or
>more distinct variable types with simultaneous access to both, e.g. it is
>an example of a memory block shared between data types. This is not allowed
>in Java because of strong typing.
>
>You have arranged to create a single 32-bit word datatype to represent
>everything, so there is no distinction between one kind of variable and
>another. Therefore there are no disparate data types, therefore there are
>no unions as that term is understood.
>
>But, as I say above, prove me wrong. Post the Java bytecode that unites a
>Java float and a Java integer in the same address space, something not
>allowed in Java.[/color]

Here's an example:

#include <stdio.h>

typedef union abc
{ int x;
float y;
} a_union;

main()
{ a_union z;

z.x = 1078531719;
printf("int val = %d\n", z.x);
printf("float val = %f\n", z.y);

z.y = 3.142;
printf("int val = %d\n", z.x);
printf("float val = %f\n", z.y);
}

MPC produced:
int val = 1078531719
float val = 3.142
int val = 1078531719
float val = 3.142

gcc produced:
int val = 1078531719
float val = 3.142000
int val = 1078531719
float val = 3.142000


Napi

--

http://www.cs.indiana.edu/hyplan/napi.html

[CBFalconer]

Re: C to Java Byte Code

Paul Lutus wrote:[color=blue]
> Willem wrote:
>[/color]
.... snip ...[color=blue]
>[color=green]
>> ) But if they are both Java native integers, no mapping is taking
>> place. If ) there are two accesses to a simple integer value, the
>> term "mapping" is not ) appropriate, but if a C union is provided
>> and two different data types are ) mapped/conjoined, the term in[/color]
>
> You really need to set up your newsreader properly. Use this post
> as an example of standard quoting style.[/color]

His problem is extremely simple - stop using a non-standard quote
character. The standard is '>', not ')'.

--
Chuck F (cbfalconer@yah oo.com) (cbfalconer@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!

[Paul Lutus]

Re: C to Java Byte Code

Mohd Hanafiah Abdullah wrote:

/ ...
[color=blue][color=green]
>>But, as I say above, prove me wrong. Post the Java bytecode that unites a
>>Java float and a Java integer in the same address space, something not
>>allowed in Java.[/color]
>
> Here's an example:
>
> #include <stdio.h>
>
> typedef union abc
> { int x;
> float y;
> } a_union;
>
> main()
> { a_union z;
>
> z.x = 1078531719;
> printf("int val = %d\n", z.x);
> printf("float val = %f\n", z.y);
>
> z.y = 3.142;
> printf("int val = %d\n", z.x);
> printf("float val = %f\n", z.y);
> }
>
> MPC produced:
> int val = 1078531719
> float val = 3.142
> int val = 1078531719
> float val = 3.142[/color]

1. This doesn't reply to my post's request.

2. This is not a union, it it two instances of the same variable. Again, to
reply to my post, you need to provide the Java bytecode that unites a Java
float and a Java integer in the same address space, something that is not
allowed in Java.

I would ask that you post an example of two data types of innately different
sizes, but you have already designed your way out of that possibility,
along with any support for doubles and other data types larger or smaller
than 32 bits.

To summarize, this is a commercial exploitation of Usenet for private gain,
an attempt to market a product with hype rather than truth. The description
of the product in the thread by Mr. Abdullah directly, and on his Website,
simply does not correspond to the truth.

According to Mr. Abdullah, a little "tweaking" will make a typical C program
compatible with his product. But in tests and in the few moments of candor
from these threads, this turns out not to be true for several reasons.
Interested readers can read this thread and the one Mr. Abdullah abandoned
to assemble a more accurate picture.

I call on Mr. Abdullah to release review copies of his product to
professional reviewers, rather than try to construct set pieces that have
little to do with the information requested, while valiantly trying to
exploit Usenet for private gain.

--
Paul Lutus

http://www.arachnoid.com

[Keith Thompson]

Re: C to Java Byte Code

Paul Lutus <nospam@nosite. zzz> writes:[color=blue]
> Mohd Hanafiah Abdullah wrote:[color=green][color=darkred]
>>>But, as I say above, prove me wrong. Post the Java bytecode that unites a
>>>Java float and a Java integer in the same address space, something not
>>>allowed in Java.[/color]
>>
>> Here's an example:
>>
>> #include <stdio.h>
>>
>> typedef union abc
>> { int x;
>> float y;
>> } a_union;
>>
>> main()
>> { a_union z;
>>
>> z.x = 1078531719;
>> printf("int val = %d\n", z.x);
>> printf("float val = %f\n", z.y);
>>
>> z.y = 3.142;
>> printf("int val = %d\n", z.x);
>> printf("float val = %f\n", z.y);
>> }
>>
>> MPC produced:
>> int val = 1078531719
>> float val = 3.142
>> int val = 1078531719
>> float val = 3.142[/color]
>
> 1. This doesn't reply to my post's request.
>
> 2. This is not a union, it it two instances of the same variable. Again, to
> reply to my post, you need to provide the Java bytecode that unites a Java
> float and a Java integer in the same address space, something that is not
> allowed in Java.[/color]

How is this not a union? What do you think a union is, anyway?

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Paul Lutus]

Re: C to Java Byte Code

Keith Thompson wrote:
[color=blue]
> Paul Lutus <nospam@nosite. zzz> writes:[/color]

/ ...
[color=blue][color=green]
>> 1. This doesn't reply to my post's request.
>>
>> 2. This is not a union, it it two instances of the same variable. Again,
>> to reply to my post, you need to provide the Java bytecode that unites a
>> Java float and a Java integer in the same address space, something that
>> is not allowed in Java.[/color]
>
> How is this not a union? What do you think a union is, anyway?[/color]

A union is two or more disparate variable types that share the same memory
space. Because of its strong data typing, Java simply doesn't allow this.
As a result, the program in question has to jump through hoops to pretend
to support a union such as is imagined to exist in the above examples and
those I provided earlier.

This is why I asked to see the Java bytecode, and this is why Mr. Abdullah
refused my request.

--
Paul Lutus

http://www.arachnoid.com

[Richard Herring]

Re: C to Java Byte Code

In message <10nre1ja02ulld c@corp.supernew s.com>, Paul Lutus
<nospam@nosite. zzz> writes

[too much]

You don't appear to be discussing C++ here, so please remove
comp.lang.c++ from the newsgroups list in your future postings.

Followups set.

A study of BCPL 's type system might shed more light, in any case ;-)
--
Richard Herring

[CBFalconer]

Re: C to Java Byte Code

Mohd Hanafiah Abdullah wrote:[color=blue]
>[/color]
.... snip ...[color=blue]
>
> Here's an example:
>
> #include <stdio.h>
>
> typedef union abc
> { int x;
> float y;
> } a_union;
>
> main()
> { a_union z;
>
> z.x = 1078531719;
> printf("int val = %d\n", z.x);
> printf("float val = %f\n", z.y);[/color]

illegal statement here. You cannot access a field of a union as a
type other than what you last wrote into it.
[color=blue]
>
> z.y = 3.142;
> printf("int val = %d\n", z.x);
> printf("float val = %f\n", z.y);[/color]

Same thing here.
[color=blue]
> }
>
> MPC produced:[/color]

Meaningless. This is undefined behavior.


--
Chuck F (cbfalconer@yah oo.com) (cbfalconer@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!