Porting GCC to 8051 Microcontroller

Porting GCC to 8051 Microcontroller

[Ganesh]

I am planning to do GCC porting for 8051 Microcontroller.
 
Kindly send me the steps involved in this project.
 
Regards,
Ganesh

Re: Porting GCC to 8051 Microcontroller

[Fabian Cenedese]

At 12:59 07.05.2008 +0530, Ganesh wrote:
>I am planning to do GCC porting for 8051 Microcontroller.
>Kindly send me the steps involved in this project.

Are there specific reasons to use gcc? Otherwise there are other
open source compilers like http://sdcc.sourceforge.net/ 

bye  Fabi

Re: Porting GCC to 8051 Microcontroller

[Ganesh]

When I visited a trade show last month, I found that GCC and 8051 are among 
the list of hot markets. I will also check SDCC. Thanks.

Ganesh.

----- Original Message ----- 
From: "Fabian Cenedese" <Cenedese@indel.ch>
To: <gcc-help@gcc.gnu.org>
Sent: Wednesday, May 07, 2008 1:20 PM
Subject: Re: Porting GCC to 8051 Microcontroller


> At 12:59 07.05.2008 +0530, Ganesh wrote:
>>I am planning to do GCC porting for 8051 Microcontroller.
>>Kindly send me the steps involved in this project.
>
> Are there specific reasons to use gcc? Otherwise there are other
> open source compilers like http://sdcc.sourceforge.net/
>
> bye  Fabi
>
> 

Re: Porting GCC to 8051 Microcontroller

[Andrew Haley]

Ganesh wrote:
> I am planning to do GCC porting for 8051 Microcontroller.
> 
> Kindly send me the steps involved in this project.

Well, if you don't understand the steps involved I don't see
why you're planning to do the port.  The 8051 architecture has
a number of features that will make it very hard to generate
code with gcc.  

The gccint info file has most of the info you need to do the
port.

Andrew.
  

Re: Porting GCC to 8051 Microcontroller

[Ganesh]

I haven't said that I don't understand the steps involved. I have just now 
started to work on it. I want to check whether if anyone have ever tried 
this port and successfully completed it.

Thanks for your input (gccint info file).


----- Original Message ----- 
From: "Andrew Haley" <aph@redhat.com>
To: "Ganesh" <ganesh@acmet.com>
Cc: <gcc-help@gcc.gnu.org>
Sent: Wednesday, May 07, 2008 1:45 PM
Subject: Re: Porting GCC to 8051 Microcontroller


> Ganesh wrote:
>> I am planning to do GCC porting for 8051 Microcontroller.
>>
>> Kindly send me the steps involved in this project.
>
> Well, if you don't understand the steps involved I don't see
> why you're planning to do the port.  The 8051 architecture has
> a number of features that will make it very hard to generate
> code with gcc.
>
> The gccint info file has most of the info you need to do the
> port.
>
> Andrew.
> 

Re: Porting GCC to 8051 Microcontroller

[Andrew Haley]

Ganesh wrote:
> I haven't said that I don't understand the steps involved. I have just
> now started to work on it. I want to check whether if anyone have ever
> tried this port and successfully completed it.

It's very unlikely.  It's not completely impossible to do it, but
code quality would probably be poor.

See http://gcc.gnu.org/ml/gcc/2003-07/msg00890.html
http://gcc.gnu.org/ml/gcc/2003-07/msg01167.html

Andrew.

>> Ganesh wrote:
>>> I am planning to do GCC porting for 8051 Microcontroller.
>>>
>>> Kindly send me the steps involved in this project.
>>
>> Well, if you don't understand the steps involved I don't see
>> why you're planning to do the port.  The 8051 architecture has
>> a number of features that will make it very hard to generate
>> code with gcc.
>>
>> The gccint info file has most of the info you need to do the
>> port.
>>
>> Andrew.
>>
> 

Re: Porting GCC to 8051 Microcontroller

[Andrew Haley]

Andrew Haley wrote:
> Ganesh wrote:
>> I haven't said that I don't understand the steps involved. I have just
>> now started to work on it. I want to check whether if anyone have ever
>> tried this port and successfully completed it.
> 
> It's very unlikely.  It's not completely impossible to do it, but
> code quality would probably be poor.
> 
> See http://gcc.gnu.org/ml/gcc/2003-07/msg00890.html
> http://gcc.gnu.org/ml/gcc/2003-07/msg01167.html

I've been thinking about this some more.  I suspect you could get good
results by generating not 8051 assembly language, which would be gross,
but a simple bytecode engine.  It wouldn't be at all fast, but it would
be possible to generate some native code sequences and intermix them
with the bytecode.  This would be a reasonable compromise between speed
and code density.

Andrew.

Re: Porting GCC to 8051 Microcontroller

[Duane Ellis]

andrew>> I've been thinking about this some more.  I 
andrew>> suspect you could get good results by 
andrew>> generating not 8051 assembly language,
andrew>> which would be gross, but a simple bytecode engine.

I know this for a fact :-) in a previous life we modeled 
the one we did off the instruction set like the MIPS. 
Why? Simple - it has to do with the way the flags 
register is done.

On some CPUs - when you add "r0 + r1" => r2, you either
*must* update the flags (zero, carry, overflow) or not.
having to maintain that in a simulator is added wasteful 
steps that you often do not need...

For example the test:

	if( a == b ){
		do_this();
	}

For us the opcodes became:
   test  r1=r2    ;; test(r1==r2)
   braf  +4	   ; branch if false
   jsr24 do_this   ; 24bit relative call.

This simplified the interpretation code and was a 
huge performance win on a 6502 @ 1mhz.

The simulation engine was a big 6502 switch statement.

In effect, the 6502 was a micro-code engine :-)

-Duane.